Rise of the Super Telescopes: The James Webb Space Telescope

A full-scale model of the JWST went on a bit of a World Tour. Here it is in Munich, Germany. Image Credit: EADS Astrium

We humans have an insatiable hunger to understand the Universe. As Carl Sagan said, “Understanding is Ecstasy.” But to understand the Universe, we need better and better ways to observe it. And that means one thing: big, huge, enormous telescopes.
In this series we’ll look at 6 of the world’s Super Telescopes:

The Giant Magellan Telescope
The Overwhelmingly Large Telescope
The 30 Meter Telescope
The European Extremely Large Telescope
The Large Synoptic Survey Telescope
The James Webb Space Telescope
The Wide Field Infrared Survey Telescope

The James Webb Space Telescope

The James Webb Space Telescope“>James Webb Space Telescope (JWST, or the Webb) may be the most eagerly anticipated of the Super Telescopes. Maybe because it has endured a tortured path on its way to being built. Or maybe because it’s different than the other Super Telescopes, what with it being 1.5 million km (1 million miles) away from Earth once it’s operating.

The JWST will do its observing while in what’s called a halo orbit at L2, a sort of gravitationally neutral point 1.5 million km from Earth. Image: NASA/JWST

If you’ve been following the drama behind the Webb, you’ll know that cost overruns almost caused it to be cancelled. That would’ve been a real shame.

The JWST has been brewing since 1996, but has suffered some bumps along the road. That road and its bumps have been discussed elsewhere, so what follows is a brief rundown.

Initial estimates for the JWST were a $1.6 billion price tag and a launch date of 2011. But the costs ballooned, and there were other problems. This caused the House of Representatives in the US to move to cancel the project in 2011. However, later that same year, US Congress reversed the cancellation. Eventually, the final cost of the Webb came to $8.8 billion, with a launch date set for October, 2018. That means the JWST’s first light will be much sooner than the other Super Telescopes.

The business end of the James Webb Space Telescope is its 18-segment primary mirror. The gleaming, gold-coated beryllium mirror has a collecting area of 25 square meters. Image: NASA/Chris Gunn

The Webb was envisioned as a successor to the Hubble Space Telescope, which has been in operation since 1990. But the Hubble is in Low Earth Orbit, and has a primary mirror of 2.4 meters. The JWST will be located in orbit at the LaGrange 2 point, and its primary mirror will be 6.5 meters. The Hubble observes in the near ultraviolet, visible, and near infrared spectra, while the Webb will observe in long-wavelength (orange-red) visible light, through near-infrared to the mid-infrared. This has some important implications for the science yielded by the Webb.

The Webb’s Instruments

The James Webb is built around four instruments:

The Near-Infrared Camera (NIRCam)
The Near-Infrared Spectrograph (NIRSpec)
The Mid-Infrared Instrument(MIRI)
The Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS)

This image shows the wavelengths of the infrared spectrum that Webb’s instruments can observe. Image: NASA/JWST

The NIRCam is Webb’s primary imager. It will observe the formation of the earliest stars and galaxies, the population of stars in nearby galaxies, Kuiper Belt Objects, and young stars in the Milky Way. NIRCam is equipped with coronagraphs, which block out the light from bright objects in order to observe dimmer objects nearby.

NIRSpec will operate in a range from 0 to 5 microns. Its spectrograph will split the light into a spectrum. The resulting spectrum tells us about an objects, temperature, mass, and chemical composition. NIRSpec will observe 100 objects at once.

MIRI is a camera and a spectrograph. It will see the redshifted light of distant galaxies, newly forming stars, objects in the Kuiper Belt, and faint comets. MIRI’s camera will provide wide-field, broadband imaging that will rank up there with the astonishing images that Hubble has given us a steady diet of. The spectrograph will provide physical details of the distant objects it will observe.

The Fine Guidance Sensor part of FGS/NIRISS will give the Webb the precision required to yield high-quality images. NIRISS is a specialized instrument operating in three modes. It will investigate first light detection, exoplanet detection and characterization, and exoplanet transit spectroscopy.

The Science

The over-arching goal of the JWST, along with many other telescopes, is to understand the Universe and our origins. The Webb will investigate four broad themes:

First Light and Re-ionization: In the early stages of the Universe, there was no light. The Universe was opaque. Eventually, as it cooled, photons were able to travel more freely. Then, probably hundreds of millions of years after the Big Bang, the first light sources formed: stars. But we don’t know when, or what types of stars.
How Galaxies Assemble: We’re accustomed to seeing stunning images of the grand spiral galaxies that exist in the Universe today. But galaxies weren’t always like that. Early galaxies were often small and clumpy. How did they form into the shapes we see today?

The Birth of Stars and Protoplanetary Systems: The Webb’s keen eye will peer straight through clouds of dust that ‘scopes like the Hubble can’t see through. Those clouds of dust are where stars are forming, and their protoplanetary systems. What we see there will tell us a lot about the formation of our own Solar System, as well as shedding light on many other questions.

Planets and the Origins of Life: We now know that exoplanets are common. We’ve found thousands of them orbiting all types of stars. But we still know very little about them, like how common atmospheres are, and if the building blocks of life are common.

These are all obviously fascinating topics. But in our current times, one of them stands out among the others: Planets and the Origins of Life.

The recent discovery the TRAPPIST 1 system has people excited about possibly discovering life in another solar system. TRAPPIST 1 has 7 terrestrial planets, and 3 of them are in the habitable zone. It was huge news in February 2017. The buzz is still palpable, and people are eagerly awaiting more news about the system. That’s where the JWST comes in.

One big question around the TRAPPIST system is “Do the planets have atmospheres?” The Webb can help us answer this.

The NIRSpec instrument on JWST will be able to detect any atmospheres around the planets. Maybe more importantly, it will be able to investigate the atmospheres, and tell us about their composition. We will know if the atmospheres, if they exist, contain greenhouse gases. The Webb may also detect chemicals like ozone and methane, which are biosignatures and can tell us if life might be present on those planets.

You could say that if the James Webb were able to detect atmospheres on the TRAPPIST 1 planets, and confirm the existence of biosignature chemicals there, it will have done its job already. Even if it stopped working after that. That’s probably far-fetched. But still, the possibility is there.

Launch and Deployment

The science that the JWST will provide is extremely intriguing. But we’re not there yet. There’s still the matter of JWST’s launch, and it’s tricky deployment.

The JWST’s primary mirror is much larger than the Hubble’s. It’s 6.5 meters in diameter, versus 2.4 meters for the Hubble. The Hubble was no problem launching, despite being as large as a school bus. It was placed inside a space shuttle, and deployed by the Canadarm in low earth orbit. That won’t work for the James Webb.

This image shows the Hubble Space Telescope being held above the shuttle’s cargo bay by the Canadian-built Remote Manipulator System (RMS) arm, or Canadarm. A complex operation, but not as complex as JWST’s deployment. Image: NASA

The Webb has to be launched aboard a rocket to be sent on its way to L2, it’s eventual home. And in order to be launched aboard its rocket, it has to fit into a cargo space in the rocket’s nose. That means it has to be folded up.

The mirror, which is made up of 18 segments, is folded into three inside the rocket, and unfolded on its way to L2. The antennae and the solar cells also need to unfold.

Unlike the Hubble, the Webb needs to be kept extremely cool to do its work. It has a cryo-cooler to help with that, but it also has an enormous sunshade. This sunshade is five layers, and very large.

We need all of these components to deploy for the Webb to do its thing. And nothing like this has been tried before.

The Webb’s launch is only 7 months away. That’s really close, considering the project almost got cancelled. There’s a cornucopia of science to be done once it’s working.

But we’re not there yet, and we’ll have to go through the nerve-wracking launch and deployment before we can really get excited.

March 8, 2017March 9, 2017 by Ken Kremer

1st SLS 2nd Stage Arrives at Cape for NASA’s Orion Megarocket Moon Launch in 2018

Composite view of the interim cryogenic propulsion stage (ICPS) for first flight of NASA's Space Launch System (SLS) rocket at United Launch Alliance manufacturing facility in Decatur, Alabama in December 2016 (left) and arrival of ICPS in a canister aboard the firm’s Delta Mariner barge on March 7, 2017 (right). Credits: ULA (left) and Ken Kremer/kenkremer.com (right)

PORT CANAVERAL – Bit by bit, piece by piece, the first of NASA’s SLS megarockets designed to propel American astronauts on deep space missions back to the Moon and beyond to Mars is at last coming together on the Florida Space Coast. And the first big integrated piece of actual flight hardware – the powerful second stage named the Interim Cryogenic Propulsion Stage (ICPS) – has just arrived by way of barge today (Mar. 7) at Port Canaveral, Fl.

The ICPS will propel NASA’s new Orion crew capsule on its maiden uncrewed mission around the Moon – currently slated for blastoff on the inaugural SLS monster rocket on the Exploration Mission-1 (EM-1) mission late next year.

SLS-1/Orion EM-1 will launch from pad 39B at NASA’s Kennedy Space Center in late 2018. The SLS will be the most powerful rocket in world history.

NASA is currently evaluating whether to add a crew of 2 astronauts to the SLS-1 launch which would result in postponing the inaugural liftoff into 2019 – as I reported here.

The interim cryogenic propulsion stage (ICPS) for first flight of NASA’s Space Launch System (SLS) rocket arrived at Port Canaveral, Florida on March 7, 2017 loaded inside a shipping canister (right) aboard the ULA Delta Mariner barge that set sail from Decatur, Alabama a week ago. The ICPS shared the shipping voyage along with a ULA Delta IV first stage rocket core seen at left. Credit: Ken Kremer/kenkremer.com

The SLS upper stage – designed and built by United Launch Alliance (ULA) and Boeing – arrived safely by way of the specially-designed ship called the Delta Mariner early Tuesday morning, Mar. 7, into the channel of Port Canaveral, Florida – as witnessed by this author.

“We are proud to be working with The Boeing Company and NASA to further deep space exploration!” ULA said in a statement.

Major assembly of the ICPS was completed at ULA’s Decatur, Alabama, manufacturing facility in December 2016.

The interim cryogenic propulsion stage (ICPS) for the first flight of NASA’s Space Launch System (SLS) rocket has arrived by way of barge at Cape Canaveral Air Force Station in Florida on March 7, 2017. The ICPS will be moved to United Launch Alliance’s Delta IV Operation Center at the Cape for processing for the SLS-1/Orion EM-1 launch currently slated for late 2018 launch from pad 39B at NASA’s Kennedy Space Center. Credit: ULA

The ICPS is the designated upper stage for the first maiden launch of the initial Block 1 version of the SLS.

It is based on ULA’s Delta Cryogenic Second Stage which has successfully flown numerous times on the firm’s Delta IV family of rockets.

In the event that NASA decides to add a two person crew to the EM-1 mission, Bill Hill, NASA’s deputy associate administrator for Exploration Systems Development in Washington, D.C., stated that the agency would maintain the Interim Cryogenic Propulsion stage for the first flight, and not switch to the more advanced and powerful Exploration Upper Stage (EUS) planned for first use on the EM-2 mission.

The ULA Delta Mariner barge arriving in Port Canaveral, Florida on March 7, 2017 after transporting the interim cryogenic propulsion stage (ICPS) hardware for the first flight of NASA’s Space Launch System (SLS) rocket from Decatur, Alabama. SLS-1 launch from the Kennedy Space Center is slated for late 2018. Credit: Ken Kremer/kenkremer.com

The ICPS was loaded onto the Delta Mariner and departed Decatur last week to began its sea going voyage of more than 2,100 miles (3300 km). The barge trip normally takes 8 to 10 days.

“ULA has completed production on the interim cryogenic propulsion stage (ICPS) flight hardware for NASA’s Space Launch System and it’s on the way to Cape Canaveral aboard the Mariner,” ULA noted in a statement last week.

The 312-foot-long (95-meter-long) ULA ship docked Tuesday morning at the wharf at Port Canaveral to prepare for off loading from the roll-on, roll-off vessel.

The Delta Mariner can travel on both rivers and open seas and navigate in waters as shallow as nine feet.

“ICPS, the first integrated SLS hardware to arrive at the Cape, will provide in-space propulsion for the SLS rocket on its Exploration Mission-1 (EM-1) mission,” according to ULA.

The next step for the upper stage is ground transport to United Launch Alliance’s Delta IV Operation Center on Cape Canaveral Air Force Station in Florida for further testing and processing before being moved to the Kennedy Space Center.

ULA will deliver the ICPS to NASA in mid-2017.

“It will be the first integrated piece of SLS hardware to arrive at the Cape and undergo final processing and testing before being moved to Ground Systems Development Operations at NASA’s Kennedy Space Center,” said NASA officials.

“The ICPS is a liquid oxygen/liquid hydrogen-based system that will provide the thrust needed to send the Orion spacecraft and 13 secondary payloads beyond the moon before Orion returns to Earth.”

The upper stage is powered by a single RL-10B-2 engine fueled by liquid hydrogen and oxygen and generates 24,750 pounds of thrust. It measures 44 ft 11 in (13.7 m ) in length and 16 ft 5 in (5 m) in width.

The interim cryogenic propulsion stage (ICPS) for the first flight of NASA’s Space Launch System (SLS) rocket as it completed major assembly at United Launch Alliance in Decatur, Alabama in December 2016. The ICPS just arrived by way of barge at Cape Canaveral Air Force Station in Florida on March 7, 2017. It will propel the Orion EM-1 crew module around the Moon. The SLS-1/Orion EM-1 launch is currently slated for late 2018 launch from NASA’s Kennedy Space Center. Credit: ULA

All major elements of the SLS will be assembled for flight inside the high bay of NASA’s iconic Vehicle Assembly Building which is undergoing a major overhaul to accommodate the SLS. The VAB high bay was extensively refurbished to convert it from Space Shuttle to SLS assembly and launch operations.

NASA’s Space Launch System (SLS) blasts off from launch pad 39B at the Kennedy Space Center in this artist rendering showing a view of the liftoff of the Block 1 70-metric-ton (77-ton) crew vehicle configuration. Credit: NASA/MSFC

For SLS-1 the mammoth booster will launch in its initial 70-metric-ton (77-ton) Block 1 configuration with a liftoff thrust of 8.4 million pounds – more powerful than NASA’s Saturn V moon landing rocket.

Components of the SLS-1 rocket are being manufactured at NASA’s Michoud Assembly Facility and elsewhere around the country by numerous suppliers.

Michoud is building the huge liquid oxygen/liquid hydrogen SLS core stage fuel tank, derived from the Space Shuttle External Tank (ET) – as I detailed here.

The liquid hydrogen tank qualification test article for NASA’s new Space Launch System (SLS) heavy lift rocket lies horizontally after final welding was completed at NASA’s Michoud Assembly Facility in New Orleans in July 2016. Credit: Ken Kremer/kenkremer.com

The ICPS sits on top of the SLS core stage.

The next Delta IV rocket launching with a Delta Cryogenic Second Stage is tentatively slated for March 14 from pad 37 at the Cape.

The Orion EM-1 capsule is currently being manufactured at the Neil Armstrong Operations and Checkout Building at the Kennedy Space Center by prime contractor Lockheed Martin.

Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2018 atop the SLS rocket. Credit: Ken Kremer/kenkremer.com

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

File photo of the ULA Delta Mariner barge arriving in Port Canaveral, Florida after transporting rocket hardware from Decatur, Alabama

March 8, 2017 by Fraser Cain

What Did Cassini Teach Us?

Ask me my favorite object in the Solar System, especially to see through a telescope, and my answer is always the same: Saturn.

Saturn is this crazy, ringed world, different than any other place we’ve ever seen. And in a small telescope, you can really see the ball of the planet, you can see its rings. It’s one thing to see a world like this from afar, a tiny jumping image in a telescope. To really appreciate and understand a place like Saturn, you’ve got to visit.

And thanks to NASA’s Cassini spacecraft, that’s just what we’ve been doing for the last 13 years. Take a good close look at this amazing ringed planet and its moons, and studying it from every angle.

Space Probes — Cassini orbiting Saturn. Credit: NASA

Throughout this article, I’m going to regale you with the amazing discoveries made by Cassini at Saturn. What it taught us, and what new mysteries it uncovered.

NASA’s Cassini spacecraft was launched from Earth on October 15, 1997. Instead of taking the direct route, it made multiple flybys of Venus, a flyby of Earth and a flyby of Jupiter. Each one of these close encounters boosted Cassini’s velocity, allowing it to make the journey with less escape velocity from Earth.

It arrived at Saturn on July 1st, 2004 and began its science operations shortly after that. The primary mission lasted 4 years, and then NASA extended its mission two more times. The first ending in 2010, and the second due to end in 2017. But more on that later.

Before Cassini, we only had flybys of Saturn. NASA’s Pioneer 11, and Voyagers 1 and 2 both zipped past the planet and its moons, snapping pictures as they went.

But Cassini was here to stay. To orbit around and around the planet, taking photos, measuring magnetic fields, and studying chemicals.

For Saturn itself, Cassini was able to make regular observations of the planet as it passed through entire seasons. This allowed it to watch how the weather and atmospheric patterns changed over time. The spacecraft watched lightning storms dance through the cloudtops at night.

This series of images from NASA’s Cassini spacecraft shows the development of the largest storm seen on the planet since 1990. These true-color and composite near-true-color views chronicle the storm from its start in late 2010 through mid-2011, showing how the distinct head of the storm quickly grew large but eventually became engulfed by the storm’s tail. Credit: NASA/JPL-Caltech/Space Science Institute

Two highlights. In 2010, Cassini watched a huge storm erupt in the planet’s northern hemisphere. This storm dug deep into Saturn’s lower atmosphere, dredging up ice from a layer 160 kilometers below and mixing it onto the surface. This was the first time that astronomers were able to directly study this water ice on Saturn, which is normally in a layer hidden from view.

Natural color images taken by NASA’s Cassini wide-angle camera, showing the changing appearance of Saturn’s north polar region between 2012 and 2016.. Credit: NASA/JPL-Caltech/Space Science Institute/Hampton University

The second highlight, of course, is the massive hexagonal storm churning away in Saturn’s northern pole. This storm was originally seen by Voyager, but Cassini brought its infrared and visible wavelength instruments to bear.

Why a hexagon? That’s still a little unclear, but it seems like when you rotate fluids of different speeds, you get multi-sided structures like this.

Cassini showed how the hexagonal storm has changed in color as Saturn moved through its seasons.

This is one of my favorite images sent back by Cassini. It’s the polar vortex at the heart of the hexagon. Just look at those swirling clouds.

The polar vortex, in all its glory. Credit: NASA/JPL-Caltech/Space Science Institute

Now, images of Saturn itself are great and all, but there was so much else for Cassini to discover in the region.

Cassini studied Saturn’s rings in great detail, confirming that they’re made up of ice particles, ranging in size as small a piece of dust to as large as a mountain. But the rings themselves are actually quite thin. Just 10 meters thick in some places. Not 10 kilometers, not 10 million kilometers, 10 meters, 30 feet.

The spacecraft helped scientists uncover the source of Saturn’s E-ring, which is made up of fresh icy particles blasting out of its moon Enceladus. More on that in a second too.

Vertical structures, among the tallest seen in Saturn’s main rings, rise abruptly from the edge of Saturn’s B ring to cast long shadows on the ring in this image taken by NASA’s Cassini spacecraft two weeks before the planet’s August 2009 equinox. Credit: NASA/JPL/Space Science Institute

Here’s another one of my favorite images of the mission. You’re looking at strange structures in Saturn’s B-ring. Towering pillars of ring material that rise 3.5 kilometers above the surrounding area and cast long shadows. What is going on here?

They’re waves, generated in the rings and enhanced by nearby moons. They move and change over time in ways we’ve never been able to study anywhere else in the Solar System.

Daphnis, one of Saturn’s ring-embedded moons, is featured in this view, kicking up waves as it orbits within the Keeler gap. Credit: NASA/JPL-Caltech/Space Science Institute

Cassini has showed us that Saturn’s rings are a much more dynamic place than we ever thought. Some moons are creating rings, other moons are absorbing or distorting them. The rings generate bizarre spoke patterns larger than Earth that come and go because of electrostatic charges.

Speaking of moons, I’m getting to the best part. What did Cassini find at Saturn’s moons?

Let’s start with Titan, Saturn’s largest moon. Before Cassini, we only had a few low resolution images of this fascinating world. We knew Titan had a dense atmosphere, filled with nitrogen, but little else.

Cassini was carrying a special payload to assist with its exploration of Titan: the Huygens lander. This tiny probe detached from Cassini just before its arrival at Saturn, and parachuted through the cloudtops on January 14, 2005, analyzing all the way. Huygens returned images of its descent through the atmosphere, and even images of the freezing surface of Titan.

Huygen’s view of Titan. Credit: ESA/NASA/JPL/University of Arizona

But Cassini’s own observations of Titan took the story even further. Instead of a cold, dead world, Cassini showed that it has active weather, as well as lakes, oceans and rivers of hydrocarbons. It has shifting dunes of pulverized rock hard water ice.

If there’s one place that needs exploring even further, it’s Titan. We should return with sailboats, submarines and rovers to better explore this amazing place.

A view of Mimas from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute

We learned, without a shadow of a doubt, that Mimas absolutely looks like the Death Star. No question. But instead of a megalaser, this moon has a crater a third of its own size.

Saturn’s moon Iapetus. Image credit: NASA/JPL/SSI

Cassini helped scientists understand why Saturn’s moon Iapetus has one light side and one dark side. The moon is tidally locked to Saturn, its dark side always leading the moon in orbit. It’s collecting debris from another Saturnian moon, Phoebe, like bugs hitting the windshield of a car.

Perhaps the most exciting discovery that Cassini made during its mission is the strange behavior of Saturn’s moon Enceladus. The spacecraft discovered that there are jets of water ice blasting out of the moon’s southern pole. An ocean of liquid water, heated up by tidal interactions with Saturn, is spewing out into space.

And as you know, wherever we find water on Earth, we find life. We thought that water in the icy outer Solar System would be hard to reach, but here it is, right at the surface, venting into space, and waiting for us to come back and investigate it further.

Icy water vapor geysers erupting from fissures on Enceladus. Credit: NASA/JPL

On September 15, 2017, the Cassini mission will end. How do we know it’s going to happen on this exact date? Because NASA is going to crash the spacecraft into Saturn, killing it dead.

That seems a little harsh, doesn’t it, especially for a spacecraft which has delivered so many amazing images to us over nearly two decades of space exploration? And as we’ve seen from NASA’s Opportunity rover, still going, 13 years longer than anticipated. Or the Voyagers, out in the depths of the void, helping us explore the boundary between the Solar System and interstellar space. These things are built to last.

The problem is that the Saturnian system contains some of the best environments for life in the Solar System. Saturn’s moon Enceladus, for example, has geysers of water blasting out into space.

Cassini spacecraft is covered in Earth-based bacteria and other microscopic organisms that hitched a ride to Saturn, and would be glad to take a nice hot Enceladian bath. All they need is liquid water and a few organic chemicals to get going, and Enceladus seems to have both.

NASA feels that it’s safer to end Cassini now, when they can still control it, than to wait until they lose communication or run out of propellant in the future. The chances that Cassini will actually crash into an icy moon and infect it with our Earth life are remote, but why take the risk?
For the last few months, Cassini has been taking a series of orbits to prepare itself for its final mission. Starting in April, it’ll actually cross inside the orbit of the rings, getting closer and closer to Saturn. And on September 15th, it’ll briefly become a meteor, flashing through the upper atmosphere of Saturn, gone forever.

This graphic illustrates the Cassini spacecraft’s trajectory, or flight path, during the final two phases of its mission. The view is toward Saturn as seen from Earth. The 20 ring-grazing orbits are shown in gray; the 22 grand finale orbits are shown in blue. The final partial orbit is colored orange. Image credit: NASA/JPL-Caltech/Space Science Institute

Even in its final moments, Cassini is going to be sciencing as hard as it can. We’ll learn more about the density of consistency of the rings close to the planet. We’ll learn more about the planet’s upper atmosphere, storms and clouds with the closest possible photographs you can take.

And then it’ll all be over. The perfect finale to one of the most successful space missions in human history. A mission that revealed as many new mysteries about Saturn as it helped us answer. A mission that showed us not only a distant alien world, but our own planet in perspective in this vast Solar System. I can’t wait to go back.

How have the photos from Cassini impacted your love of astronomy? Let me know your thoughts in the comments.

March 8, 2017February 18, 2017 by Matt Williams

How Long is Day on Mercury?

Mosaic of Mercury. Credit: NASA / JHUAPL / CIW / mosaic by Jason Perry

Mercury is one of the most unusual planets in our Solar System, at least by the standards of us privileged Earthlings. Despite being the closest planet to our Sun, it is not the hottest (that honor goes to Venus). And because of its virtually non-existence atmosphere and slow rotation, temperatures on its surface range from being extremely hot to extremely cold.

Equally unusual is the diurnal cycle on Mercury – i.e. the cycle of day and night. A single year lasts only 88 days on Mercury, but thanks again to its slow rotation, a day lasts twice as long! That means that if you could stand on the surface of Mercury, it would take a staggering 176 Earth days for the Sun to rise, set and rise again to the same place in the sky just once!

Distance and Orbital Period:

Mercury is the closest planet to our Sun, but it also has the most eccentric orbit (0.2056) of any of the Solar Planets. This means that while its average distance (semi-major axis) from the Sun is 57,909,050 km (35,983,015 mi) or 0.387 AUs, this ranges considerably – from 46,001,200 km (2,8583,820 mi) at perihelion (closet) to 69,816,900 km (43,382,210 mi) at aphelion (farthest).

*A timelapse of Mercury transiting across the face of the Sun. Credit: NASA*

Because of this proximity, Mercury has a rapid orbital period, which varies depending on where it is in its orbit. Naturally, it moves fastest when it is at its closest to the Sun, and slowest when it is farthest. On average, its orbital velocity is 47.362 km/s (29.43 mi/s), which means it takes only 88 days to complete a single orbit of the Sun.

Astronomers used to suspect that Mercury was tidally locked to the Sun, meaning that it always showed the same face to the Sun – similar to how the Moon is tidally locked to the Earth. But radar-Doppler measurements obtained in 1965 demonstrated that Mercury is actually rotating very slowly compared to the Sun.

Sidereal vs. Solar Day:

Based on data obtained by these radar measurements, Mercury is now known to be in 3:2 orbital resonance with the Sun. This means that the planet completes three rotations on its axis for every two orbits it makes around the Sun. At it’s current rotational velocity – 3.026 m/s, or 10.892 km/h (6.77 mph) – it takes Mercury 58.646 days to complete a single rotation on its axis.

While this might lead some to conclude that a single day on Mercury is about 58 Earth days – thus making the length of a day and year correspond to the same 3:2 ratio – this would be inaccurate. Due to its rapid orbital velocity and slow sidereal rotation, a Solar Day on Mercury (the time it takes for the Sun to return to the same place in the sky) is actually 176 days.

In that respect, the ratio of days to years on Mercury is actually 1:2. The only places that are exempt to this day and night cycle are the polar regions. The cratered northern polar region, for example, exists in a state of perpetual shadow. Temperatures in these craters are also cool enough that significant concentrations of water ice can exist in stable form.

For over 20 years, scientists believed that radar-bright images from Mercury’s northern polar regions might indicate the presence of water ice there. In November of 2012, NASA’s MESSENGER probe examined the northern polar region using its neutron spectrometer and laser altimeter and confirmed the presence of both water ice and organic molecules.

*View of Mercury’s north pole. based on MESSENGER probe data, showing polar deposits of water ice. Credit: NASA/JHUAPL/Carnegie Institute of Science/NAIC/Arecibo Observatory*

Yes, as if Mercury weren’t strange enough, it turns out that a single day on Mercury lasts as long as two years! Just another oddity for a planet that likes to keep things really hot, really cold, and is really eccentric.

We’ve written many articles about Mercury for Universe Today. Here’s How Long is Day on the Other Planets?, Which Planet has the Longest Day?, How Long is a Day on Venus?, How Long is a Day on Earth?, How Long is a Day on the Moon?, How Long is a Day on Mars?, How Long is a Day on Jupiter?, How Long is a Day on Saturn?, How Long is a Day on Uranus?, How Long is a Day on Neptune?, and How Long is a Day on Pluto?

If you’d like more info on Mercury, check out NASA’s Solar System Exploration Guide, and here’s a link to NASA’s MESSENGER Misson Page.

We’ve also recorded an entire episode of Astronomy Cast all about Mercury. Listen here, Episode 49: Mercury.

Sources:

March 7, 2017April 30, 2017 by Matt Williams

Exploring Titan with Balloons and Landers

ASA's Cassini spacecraft looks toward the night side of Saturn's largest moon and sees sunlight scattering through the periphery of Titan's atmosphere and forming a ring of color. Credit: NASA/JPL-Caltech/Space Science Institute

Last week – from Monday, February 27th to Wednesday, March 1st – NASA hosted the “Planetary Science Vision 2050 Workshop” at their headquarters in Washington, DC. In the course of the many presentations, speeches and panel discussions, NASA’s shared its many plans for the future of space exploration with the international community.

Among the more ambitious of these was a proposal to explore Titan using an aerial explorer and a lander. Building upon the success of the ESA’s Cassini-Huygen mission, this plan would involve a balloon that would explore Titan’s surface from low altitude, along with a Mars Pathfinder-style mission that would explore the surface.

Ultimately, the goal a mission to Titan would be to explore the rich organic chemical environment the moon has, which presents a unique opportunity for planetary researchers. For some time, scientists have understood that Titan’s surface and atmosphere have an abundance of organic compounds and all the prebiotic chemistry necessary for life to function.

*Artist depiction of Huygens landing on Titan. Credit: ESA*

The presentation, which was titled “Aerial Mobility : The Key to Exploring Titan’s Rich Chemical Diversity” was chaired by Ralph Lorenz from the Johns Hopkins Applied Physics Laboratory, and co-chaired by Elizabeth Turtle (also from John Hopkins APL) and Jason Barnes from the Dept. of Physics at the University of Idaho. As Turtle explained to Universe Today via email, Titan presents some exciting opportunities for a next-generation mission:

“Titan’s of particular interest because the abundant and complex organic chemistry can teach us about chemical interactions that could have occurred here on Earth (and elsewhere?) leading to the development of life. Furthermore, not only does Titan have an interior liquid-water ocean, but there will also have been opportunities for organic material to have mixed with liquid water at Titan’s surface, for example impact craters and possibly cryovolcanic eruptions. The combination of organic material with liquid water, of course, increases astrobiological potential.”

For this reason, the exploration of Titan has been a scientific goal for decades. The only question is how best to go about exploring Titan’s unique environment. During previous Decadal Surveys – such as the Campaign Strategy Working Group (CSWG) on Prebiotic Chemistry in the Outer Solar System, of which Lorenz was a contributor – has suggested that a mobile aerial vehicle (such as an airship or a balloon) would well-suited to the task.

However, such vehicles would be unable to study Titan’s methane lakes, which are one of the most exciting draws of the moon as far as research into prebiotic chemistry goes. What’s more, an aerial vehicle would not be able to conduct in-situ chemical analysis of the surface, much like what the Mars Exploration Rovers (Spirit, Opportunity and Curiosity) have been doing on Mars – and with immense results!

*The ESA’s TALISE (Titan Lake In-situ Sampling Propelled Explorer) on the left, and NASA’s Titan Mare Explorer (TiME) on the right. Credit: bisbos.com*

At the same time, Lorenz and his colleagues examined concepts for the exploration of Titan’s hydrocarbon seas – like the proposed Titan Mare Explorer (TiME) capsule. As one of several finalists of NASA’s 2010 Discovery competition, this concept called for the deployment of nautical robot to Titan in the coming decades, where it would study its methane lakes to learn more about the methane cycle and search for signs of organic life.

While such a proposal would be cost-effective and presents some very exciting opportunities for research, it also has some limitations. For instance, during the 2020s-2030s, Titan’s northern hemisphere will be experiencing its winter season; at which point the thickness of its atmosphere will make direct-to-Earth communications and Earth views impossible. On top of that, a nautical vehicle would preclude the exploration of Titan’s land surfaces.

These offer some of the most likely prospects for studying Titan’s advanced chemical evolution, including Titan’s dune sands. As a windswept region, this area likely has material deposited from all over Titan and may also contain aqueously altered materials. Much as the Mars Pathfinder landing site was selected so it could collect samples from a wide area, such as location would be an ideal site for a lander.

As such, Lorenz and his colleagues advocated the type of mission that was articulated in the 2007 Flagship Study, which called for a Montgolfière balloon for regional exploration and a Pathfinder-like lander. This would provide the opportunity to conduct surface imaging at resolutions that are impossible from orbit (due to the thick atmosphere) as well as investigating the surface chemistry and interior structure of the moon.

Artist’s conception of a possible structure for underground liquid reservoirs on Saturn moon’s Titan. Credit: ESA/ATG medialab

So while the balloon would gather high-resolution geographical data of the moon, the lander could conduct seismological surveys that would characterize the thickness of the ice above Titan’s internal water ocean. However, a lander mission would be limited in terms of range, and the surface of Titan presents problems for mobility. This would make multiple landers, or a relocatable lander, the most desired option.

“Potential targets include areas where we can measure solid surface materials, the composition of which is still not well known, Titan’s dune sands, for example,” said Turtle. “Detailed in situ analysis is required to determine their composition. The lakes and seas are also intriguing; however, in the nearer term (missions arriving in the 2030s) most of those will be in winter darkness. So, exploring them would likely have to wait until the 2040s.”

This mission concept would also take advantage of several technological advances that have been made in recent years. As Lorenz explained in the course of the presentation:

“Heavier-than-air mobility at Titan is in fact highly efficient, moreover, improvements in autonomous aircraft in the two decades since the CSWG make such exploration a realistic prospect. Multiple in-situ landers delivered by an aerial vehicle like an airplane or a lander with aerial mobility to access multiple sites, would provide the most desirable scientific capability, highly relevant to the themes of origins, workings, and life.”

*Updated maps of Titan, based on the Cassini imaging science subsystem. Credit: NASA/JPL/Space Science Institute*

Lorenz, Turtle and Barnes will also be presenting these findings at the upcoming 48th Lunar and Planetary Science Conference – which will be taking place from March 20th to 24th in The Woodlands, Texas. There they will be joined by additional members of the Johns Hopkins APL and the University of Idaho, as well as panelists from NASA’s Goddard Space Flight Center, Pennsylvania State University, and Honeybee Robotics.

However, addressing some additional challenges not raised at the 2050 Vision Workshop, they will be presenting a slight twist on their idea. Instead of a balloon and multiple landers, they will present a mission concept involving a “Dragonfly” qaudcopter. This four-rotor vehicle would be able to take advantage of Titan’s thick atmosphere and low gravity to obtain samples and determine the surface composition in multiple geological settings.

This concept also incorporates a lot of recent advances in technology, which include modern control electronics and advances in commerical unmanned aerial vehicle (UAV) designs. On top of that, a quadcopter would do away with chemically-powered retrorockets and could power-up between flights, giving it a potentially much longer lifespan.

These and other concepts for exploring Saturn’s moon Titan are sure to gain traction in the coming years. Given the many mysteries locked away on this world – with includes abundant water ice, prebiotic chemistry, a methane cycle, and a subsurface ocean that is likely to be a prebiotic environment – it is certainly a popular target for scientific research.

Further Reading: USRA, USRA (2), USRA (3)

March 7, 2017May 2, 2017 by Evan Gough

Rise of the Super Telescopes: The Thirty Meter Telescope

An artist's illustration of the Thirty Meter Telescope at its preferred location at Mauna Kea, Hawaii. Image Courtesy TMT International Observatory

As Carl Sagan said, “Understanding is Ecstasy.” But in order to understand the Universe, we need better and better ways to observe it. And that means one thing: big, huge, enormous telescopes.

In this series, we’ll look at six Super Telescopes being built:

The Thirty Meter Telescope

The Thirty Meter Telescope (TMT) is being built by an international group of countries and institutions, like a lot of Super Telescopes are. In fact, they’re proud of pointing out that the international consortium behind the TMT represents almost half of the world’s population; China, India, the USA, Japan, and Canada. The project needs that many partners to absorb the cost; an estimated $1.5 billion.

The heart of any of the world’s Super Telescopes is the primary mirror, and the TMT is no different. The primary mirror for the TMT is, obviously, 30 meters in diameter. It’s a segmented design consisting of 492 smaller mirrors, each one a 1.4 meter hexagon.

The light collecting capability of the TMT will be 10 times that of the Keck Telescope, and more than 144 times that of the Hubble Space Telescope.

But the TMT is more than just an enormous ‘light bucket.’ It also excels with other capabilities that define a super telescope’s effectiveness. One of those is what’s called diffraction-limited spatial resolution (DLSR).

An illustration of the segmented primary mirror of the Thirty Meter Telescope. Image Courtesy TMT International Observatory

When a telescope is pointed at distant objects that appear close together, the light from both can scatter enough to make the two objects appear as one. Diffraction-limited spatial resolution means that when a ‘scope is observing a star or other object, none of the light from that object is scattered by defects in the telescope. The TMT will more easily distinguish objects that are close to each other. When it comes to DLSR, the TMT will exceed the Keck by a factor of 3, and will exceed the Hubble by a factor of 10 at some wavelengths.

Crucial to the function of large, segmented mirrors like the TMT is active optics. By controlling the shape and position of each segment, active optics allows the primary mirror to compensate for changes in wind, temperature, or mechanical stress on the telescope. Without active optics, and its sister technology adaptive optics, which compensates for atmospheric disturbance, any telescope larger than about 8 meters would not function properly.

The TMT will operate in the near-ultraviolet, visible, and near-infrared wavelengths. It will be smaller than the European Extremely Large Telescope (E-ELT), which will have a 39 meter primary mirror. The E-ELT will operate in the optical and infrared wavelengths.

The world’s Super Telescopes are behemoths. Not just in the size of their mirrors, but in their mass. The TMT’s moving mass will be about 1,420 tonnes. Moving the TMT quickly is part of the design of the TMT, because it must respond quickly when something like a supernova is spotted. The detailed science case calls for the TMT to acquire a new target within 5 to 10 minutes.

This requires a complex computer system to coordinate the science instruments, the mirrors, the active optics, and the adaptive optics. This was one of the initial challenges of the TMT project. It will allow the TMT to respond to transient phenomena like supernovae when spotted by other telescopes like the Large Synoptic Survey Telescope.

The Science

The TMT will investigate most of the important questions in astronomy and cosmology today. Here’s an overview of major topics that the TMT will address:

The Nature of Dark Matter
The Physics of Extreme Objects like Neutron Stars
Early galaxies and Cosmic Reionization
Galaxy Formation
Super-Massive Black Holes
Exploration of the Milky Way and Nearby Galaxies
The Birth and Early Lives of Stars and Planets
Time Domain Science: Supernovae and Gamma Ray Bursts
Exo-planets
Our Solar System

This is a comprehensive list of topics, to be sure. It leaves very little out, and is a testament to the power and effectiveness of the TMT.

The raw power of the TMT is not in question. Once in operation it will advance our understanding of the Universe on multiple fronts. But the actual location of the TMT could still be in question.

Where Will the TMT Be Built?

The original location for the TMT was Mauna Kea, the 4,200 meter summit in Hawaii. Mauna Kea is an excellent location, and is the home of several telescopes, most notably the Keck Observatory, the Gemini Telescope, the Subaru Telescope, the Canada-France-Hawaii Telescope, and the James Clerk Maxwell Telescope. Mauna Kea is also the site of the westernmost antenna of the Very Long Baseline Array.

The top of Mauna Kea is a prime site for telescopes, as shown in this image. Image Courtesy Mauna Kea Observatories

The dispute between some of the Hawaiian people and the TMT has been well-documented elsewhere, but the basic complaint about the TMT is that the top of Mauna Kea is sacred land, and they would like the TMT to be built elsewhere.

The organizations behind the TMT would still like it to be built at Mauna Kea, and a legal process is unfolding around the dispute. During that process, they identified several possible alternate sites for the telescope, including La Palma in the Canary Islands. Universe Today contacted TMT Observatory Scientist Christophe Dumas, PhD., about the possible relocation of the TMT to another site.

Dr. Dumas told us that “Mauna Kea remains the preferred location for the TMT because of its superb observing conditions, and because of the synergy with other TMT partner facilities already present on the mountain. Its very high elevation of almost 14,000 feet makes it the premier astronomical site in the northern hemisphere. The sky above Mauna Kea is very stable, which allows very sharp images to be obtained. It has also excellent transparency, low light pollution and stable cold temperatures that improves sensitivity for observations in the infrared.”

The preferred secondary site at La Palma is home to over 10 other telescopes, but would relocation to the Canary Islands affect the science done by the TMT? Dr. Dumas says that the Canary Islands site is excellent as well, with similar atmospheric characteristics to Mauna Kea, including stability, transparency, darkness, and fraction of clear-nights.

The Gran Telescopio Canarias (Great Canary Telescope) is the largest ‘scope currently at La Palma. At 10m diameter, it would be dwarfed by the TMT. Image: By Pachango – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6880933

As Dr. Dumas explains, “La Palma is at a lower elevation site and on average warmer than Mauna Kea. These two factors will reduce TMT sensitivity at some wavelengths in the infrared region of the spectrum.”

Dr. Dumas told Universe Today that this reduced sensitivity in the infrared can be overcome somewhat by scheduling different observing tasks. “This specific issue can be partly mitigated by implementing an adaptive scheduling of TMT observations, to match the execution of the most demanding infrared programs with the best atmospheric conditions above La Palma.”

Court Proceedings End

On March 3rd, 44 days of court hearings into the TMT wrapped up. In that time, 71 people testified for and against the TMT being constructed on Mauna Kea. Those against the telescope say that the site is sacred land and shouldn’t have any more telescope construction on it. Those for the TMT spoke in favor of the science that the TMT will deliver to everyone, and the education opportunities it will provide to Hawaiians.

Though construction has been delayed, and people have gone to court to have the project stopped, it seems like the TMT will definitely be built—somewhere. The funding is in place, the design is finalized, and manufacturing of the components is underway. The delays mean that the TMT’s first light is still uncertain, but once we get there, the TMT will be another game-changer, just like the world’s other Super Telescopes.

March 7, 2017April 4, 2017 by Matt Williams

Reading The Signs Of A Martian Mega-Flood

Perspective view looking from an unnamed crater (bottom right) towards the Worcester Crater. The region sits at the mouth of Kasei Valles, where fierce floodwaters emptied into Chryse Planitia. Credit: ESA/DLR/FU Berlin

The Mars Express probe was the European Space Agency’s first attempt to explore Mars. Since its arrival around the Red Planet in 2003, the probe has helped determine the composition of the atmosphere, map the mineral composition of the surface, studied the interaction between the atmosphere and solar wind, and taken many high-resolution images of the surface.

And even after 14 years of continuous operation, it is still revealing interesting things about Mars and its past. The latest find comes from the Kasei Valles region, where the probe captured new images of the giant system of canyons. As one of the largest outflow channel networks on the Red Planet, this region is evidence of a massive flood having taken place billions of years ago.

This region formed between 3.6 and 3.4 billion years ago, when a combination of volcanic and tectonic activity in the Tharsis region triggered groundwater releases from Echus Chasma. This chasm, located in the Lunae Planum plateau, contains clay deposits that indicate the presence of liquid water at one time. This water then flooded through Kasei Valles, emptying into the Chryse Planitia region and leaving behind signs of water erosion.

*Colour-coded topographic view of the mouth of Kasei Valles, showing the Worcester Crater. Credit: ESA/DLR/FU Berlin.*

The Mars Express probe has captured images of this region before. But these latest images, which were snapped n May 25th, 2016, captured the topography of an area that lies at the mouth of the system. Of particular interest was the 25-km-wide Worcester Crater, the remains of an impact that has managed to remain intact despite the erosive force of the mega-flood.

The appearance of this crater and the features around it – which resemble an island – tell us much about the region and its history. For instance, the island has a stepped topography, which is likely the result of its interaction with the flood waters. After the impact threw up material around the crater, moving water pushed it downstream, creating a rigid wall facing towards Kasei Valles and a sloping wall trailing away from it.

The topography of the island is also suggestive of variations in water levels, or possibly different flood episodes. As the water rose and fell, or multiple streams formed over time, the downstream portion of the “island” was affected. There is also the larger crater that appears to the upper right of the image, which sits in a plateau 1 km (0.6 mi) higher than the plains below.

There is a small depression in its center, which would imply that a weaker layer – possibly made of ice – existed under the plateau during the time of impact. This is consistent with the patterns noted in Worcester’s debris blanket, which also suggest the area was rich in water or water-ice during the flooding. The presence of small branch-like channels (aka. dendritic channels) around the plateau are another indication that water levels here varied over time.

*Context image shows a region of Mars where Kasei Valles empties into the vast Chryse Planitia. Credit: NASA/MGS/MOLA Science Team*

Many smaller craters are also visible in this photo across the mouth of the Kasei Valles region, which also appear to have “tails” of ejected material. This is also true of the crater that sits adjacent to Worchester, who’s debris blanket appears to be largely intact. This would suggest that these craters were formed after the flooding, and any tails that formed were the result of wind.

From all this, it can be concluded that roughly three and a half billion years ago, the mouth of the Kasei Valles region still had water on its surface – possibly still in liquid form but most likely in the form of ice. Volcanic activity – which Mars was still experiencing at the time – then triggered the release of flood waters, which created debris and erosion features throughout the region.

As a result, this latest image manages to capture a preserved record of the geological activity in this region, one which goes back billions of years. And in addition to proving that Mars still had water on its surface, it also confirms that Mars was still experiencing volcanism. It is because of ongoing discoveries like these that the Mars Express mission has been extended several times, the most recent of which extended the mission to end of 2018.

Further Reading: ESA

March 7, 2017April 4, 2017 by Nancy Atkinson

Brightest ‘Spot’ on Ceres is Likely a Cryovolcano

False color mosaic showing parts of Occator crater, with a central pit containing the brightest material on Ceres. It measures 11 kilometers in diameter and in the middle of the pit a dome towers 400 meters high. The dome could be the remnant of a cryovolcano. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The bright regions on the dwarf planet Ceres have been some of the most talked about features in planetary science in recent years. While data from the Dawn spacecraft has shown these bright areas are salt deposits (alas, not lights of an alien city), the question remained of how these salts reached the surface.

Researchers with the Dawn mission say they have now thoroughly investigated the complex geological structures in Occator crater, the region with the brightest regions on Ceres. The scientists conclude that a bright dome-like feature called Cerealia Facula is the remnant of a cryovolcano — an ice volcano — that repeatedly and relatively recently spewed salty ice from within Ceres up to the surface.

“The age and appearance of the material surrounding the bright dome indicate that Cerealia Facula was formed by a recurring, eruptive process, which also hurled material into more outward regions of the central pit,” said Andreas Nathues, a Dawn scientist from the Max Planck Institute for Solar System Research. “A single eruptive event is rather unlikely.”

The bright central spots near the center of Occator Crater are shown in enhanced color in this view from NASA’s Dawn spacecraft. The view was produced by combining the highest resolution images taken in February 2016 (at image scales 115 feet (35 meters) per pixel of 35 meters with color images obtained in September 2015 at a lower resolution. Click for a highest-res view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Occator crater located in the northern hemisphere of Ceres measures 92 kilometers (57 miles) in diameter. In its center is a pit with a diameter of about 11 kilometers (7 miles). On some parts of its edges, jagged mountains and steep slopes rise up to 750 meters (820 yards) high. Within the pit a bright dome formed. It has a diameter of 3 km (1.8 miles), is 400 meters (437 yards) high, with prominent fractures.

In analyzing images from Dawn’s Framing Camera, Nathues and his team deduced that the central pit is a remnant of a former central mountain, formed from the impact that created Occator Crater about 34 million years ago. But with a method for estimating the age of a planet’s surface – called crater counting — the science team could determine the dome of bright material is only about four million years old.

This suggests, the team said, that Occator crater has been the scene of eruptive outbursts of subsurface brine over a long period and until almost recently.

Jupiter’s moons Callisto and Ganymede show similar types of domes, and researchers interpret them as signs of cryovolcanism. While Ceres is too far from the Sun to be warm enough for regular volcanic activity, it very likely has harbored cryovolcanic activity, and it may even be active today.

This 3d-anaglyph for the first time shows a part of Occator crater in a combination of anaglyphe and false-color image. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Images from the Hubble Space Telescope taken more than a decade ago hinted at the bright spots in Occator Crater, but as the Dawn spacecraft approached Ceres in 2015, new images showed the bright areas almost shining like “cosmic beacons, like interplanetary lighthouses drawing us forth,” as described by Marc Rayman, the chief engineer and mission director for Dawn, in an interview with me last year.

Dawn scientist had previously determined the bright areas were salts left over from subsurface briny water that had made its way to the surface, and in the vacuum of space, the water sublimated away, leaving behind the dissolved salts. These salts were determined to be sodium carbonate and ammonium chloride.

This view of the whole Occator crater shows the brightly colored pit in its center and the cryovolcanic dome. The jagged mountains on the edge of the pit throw their shadows on parts of the pit. This image was taken from a distance of 1478 kilometers above the surface and has a resolution of 158 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

But don’t call these bright areas “spots,” said Rayman. “Some of these bright areas are miles across,” he said, “and just as if you were standing on salt flats on Earth that were several thousand acres, you wouldn’t say, ‘I’m standing on a spot.’ You are standing on a big area. But just to see the distribution of this material in the Dawn images shows there is something complex going on there.”

It is currently unknown if the region in Occator Crater is active, but there are hints it is, at least at a low level.

In 2014 the Herschel spacecraft detected water vapor above Occator, and images from Dawn’s cameras of the crater show a ‘haze’ when imaged at certain angles, and this has been explained as the sublimation of water.

Dawn scientists are also studying the large volcanic feature on Ceres, Ahuna Mons, to determine if it could be a cryovolcano, and will continue to study other bright areas on Ceres, as well.

Ceres’ lonely mountain, Ahuna Mons, is seen in this simulated perspective view. The elevation has been exaggerated by a factor of two. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Further Reading: Max Planck Institute for Solar System Research

March 7, 2017April 4, 2017 by Matt Williams

Mineral Points To A Water Rich Mars

Scientists were able to gauge the rate of water loss on Mars by measuring the ratio of water and HDO from today and 4.3 billion years ago. Credit: Kevin Gill

For years now, scientists have understood that Mars was once a warmer, wetter place. Between terrain features that indicate the presence of rivers and lakes to mineral deposits that appeared to have dissolved in water, there is no shortage of evidence attesting to this “watery” past. However, just how warm and wet the climate was billions of years ago (and since) has been a subject of much debate.

According to a new study from an international team of scientists from the University of Nevada, Las Vegas (UNLV), it seems that Mars may have been a lot wetter than previous estimates gave it credit for. With the help of Berkeley Laboratory, they conducted simulations on a mineral that has been found in Martian meteorites. From this, they determined that Mars may have had a lot more water on its surface than previously thought.

When it comes to studying the Solar System, meteorites are sometimes the only physical evidence available to researchers. This includes Mars, where meteorites recovered from Earth’s surface have helped to shed light on the planet’s geological past and what kinds of processes have shaped its crust. For geoscientists, they are the best means of determining what Mars looked like eons ago.

*An artist’s impression of what Mars might have looked like with water, when any potential Martian microbes would have evolved. Credit: ESO/M. Kornmesser*

Unfortunately for geoscientists, these meteorites have underdone changes as a result of the cataclysmic force that expelled them from Mars. As Dr. Christopher Adcock, an Assistant Research Professor at with the Dept. of Geoscience at UNLV and the lead author of the study, told Universe Today via email:

“Martian meteorites are pieces of Mars, basically they are our only samples of Mars on Earth until there is a sample return mission. Many of the discoveries we have made about Mars came from studying martian meteorites and wouldn’t be possible without them. Unfortunately, these meteorites have all experienced shock from being ejected of the Martian surface during impacts.”

Of the over 100 Martian meteorites that have been retrieved here on Earth, and range in age from between 4 billion years to 165 million years. They are also believed to have come from only a few regions on Mars, and were likely ejecta created from impact events. And in the course of examining them, scientists have noticed the presence of a calcium phosphate mineral known as merrillite.

As a member of the whitlockite group that is commonly found in Lunar and Martian meteorities, this mineral is known for being anhydrous (i.e. containing no water). As such, researchers have drawn the conclusion that the presence of this minerals indicates that Mars had an arid environment when these rocks were ejected. This is certainly consistent with what Mars looks like today – cold, icy and dry as a bone.

*The Mojave Crater on Mars, where some of the Martians meteorites retrieved on Earth are believed to have originated from. Credit: NASA/JPL-Caltech/University of Arizona*

For the sake of their study – titled “Shock-Transformation of Whitlockite to Merrillite and the Implications for Meteoritic Phosphate“, which appeared recently in the journal Nature Communications – the international research team considered another possibility. Using a synthetic version of whitlockite, they began conducting shock compression experiments on it designed to simulate the conditions under which meteorites are ejected from Mars.

This consisted of placing the synthetic whitlockite sample inside a projectile, then using a helium gas gun to accelerate it up to speeds of 700 meters per second (2520 km/h or 1500 mph) into a metal plate – thus subjecting it to intense heat and pressure. The sample was then examined using the Berkeley Lab’s Advanced Light Source (ALS) and the Argonne National Laboratory’s Advanced Photon Source (APS) instruments.

“When we analyzed what came out of the capsule, we found a significant amount of the whitlockite had dehydrated to the mineral merrillite,” said Adcock. “Merrillite is found in many meteorites (including Martian). The means it is possible the rocks meteorites are made from originally started life with whitlockite in them in an environment with more water than previously thought. If true, it would indicate more water in the Martian past and the early Solar System.”

Not only does this find raise the “water budget” for Mars in the past, it also raises new questions about Mars’ habitability. In addition to being soluble in water, whitlockite also contains phosphorous – a crucial element for life here on Earth. Combined with recent evidence that shows that liquid water still exists on Mars’ surface – albeit intermittently – this raises new questions about whether or not Mars had life in the past (or even today).

But as Adcock explained, further experiments and evidence will be needed to determine if these results are indicative of a more watery past:

“As far as life goes, our results are very favorable for the possibility – but we need more data. Really we need a sample return mission or we need to go there in person – a human mission. Science is closing in on the answers to a number of big questions about our solar system, life elsewhere, and Mars. But it is difficult work when it all has to be done from far away.”

And sample returns are certainly on the horizon. NASA hopes to conduct the first step in this process with their Mars 2020 Rover, which will collect samples and leave them in a cache for future retrieval. The ESA’s ExoMars rover is expected to make the journey to Mars in the same year, and will also obtain samples as part of a sample-return mission to Earth.

These missions are scheduled to launch the summer of 2020, when the planets will be at their closest again. And with crewed missions to the surface planned for the following decade, we might see the first non-meteorite samples of Mars brought back to Earth for analysis.

Further Reading: Nature Communications, Berkeley Lab

March 6, 2017April 4, 2017 by Evan Gough

Towards A New Understanding Of Dark Matter

In February 2016, LIGO detected gravity waves for the first time. As this artist's illustration depicts, the gravitational waves were created by merging black holes. The third detection just announced was also created when two black holes merged. Credit: LIGO/A. Simonnet. — Artist's impression of merging binary black holes. Credit: LIGO/A. Simonnet.

Dark matter remains largely mysterious, but astrophysicists keep trying to crack open that mystery. Last year’s discovery of gravity waves by the Laser Interferometer Gravitational Wave Observatory (LIGO) may have opened up a new window into the dark matter mystery. Enter what are known as ‘primordial black holes.’

Theorists have predicted the existence of particles called Weakly Interacting Massive Particles (WIMPS). These WIMPs could be what dark matter is made of. But the problem is, there’s no experimental evidence to back it up. The mystery of dark matter is still an open case file.

When LIGO detected gravitational waves last year, it renewed interest in another theory attempting to explain dark matter. That theory says that dark matter could actually be in the form of Primordial Black Holes (PBHs), not the aforementioned WIMPS.

Primordial black holes are different than the black holes you’re probably thinking of. Those are called stellar black holes, and they form when a large enough star collapses in on itself at the end of its life. The size of these stellar black holes is limited by the size and evolution of the stars that they form from.

This artist’s drawing shows a stellar black hole as it pulls matter from a blue star beside it. Could the stellar black hole’s cousin, the primordial black hole, account for the dark matter in our Universe?
Credits: NASA/CXC/M.Weiss

Unlike stellar black holes, primordial black holes originated in high density fluctuations of matter during the first moments of the Universe. They can be much larger, or smaller, than stellar black holes. PBHs could be as small as asteroids or as large as 30 solar masses, even larger. They could also be more abundant, because they don’t require a large mass star to form.

When two of these PBHs larger than about 30 solar masses merge together, they would create the gravitational waves detected by LIGO. The theory says that these primordial black holes would be found in the halos of galaxies.

If there are enough of these intermediate sized PBHs in galactic halos, they would have an effect on light from distant quasars as it passes through the halo. This effect is called ‘micro-lensing’. The micro-lensing would concentrate the light and make the quasars appear brighter.

A depiction of quasar microlensing. The microlensing object in the foreground galaxy could be a star (as depicted), a primordial black hole, or any other compact object. Credit: NASA/Jason Cowan (Astronomy Technology Center).

The effect of this micro-lensing would be stronger the more mass a PBH has, or the more abundant the PBHs are in the galactic halo. We can’t see the black holes themselves, of course, but we can see the increased brightness of the quasars.

Working with this assumption, a team of astronomers at the Instituto de Astrofísica de Canarias examined the micro-lensing effect on quasars to estimate the numbers of primordial black holes of intermediate mass in galaxies.

“The black holes whose merging was detected by LIGO were probably formed by the collapse of stars, and were not primordial black holes.” -Evencio Mediavilla

The study looked at 24 quasars that are gravitationally lensed, and the results show that it is normal stars like our Sun that cause the micro-lensing effect on distant quasars. That rules out the existence of a large population of PBHs in the galactic halo. “This study implies “says Evencio Mediavilla, “that it is not at all probable that black holes with masses between 10 and 100 times the mass of the Sun make up a significant fraction of the dark matter”. For that reason the black holes whose merging was detected by LIGO were probably formed by the collapse of stars, and were not primordial black holes”.

Depending on you perspective, that either answers some of our questions about dark matter, or only deepens the mystery.

We may have to wait a long time before we know exactly what dark matter is. But the new telescopes being built around the world, like the European Extremely Large Telescope, the Giant Magellan Telescope, and the Large Synoptic Survey Telescope, promise to deepen our understanding of how dark matter behaves, and how it shapes the Universe.

It’s only a matter of time before the mystery of dark matter is solved.