Posted on by Matt Williams

Four Planet System Directly Imaged In Motion

Artist's concept of the multi-planet system around HR 8799, initially discovered with Gemini North adaptive optics images. Credit: Gemini Observatory/Lynette Cook"

Located about 129 light years from Earth in the direction of the Pegasus constellation is the relatively young star system of HR 8799. Beginning in 2008, four orbiting exoplanets were discovered in this system which – alongside the exoplanet Formalhaut b – were the very first to be confirmed using the direct imaging technique. And over time, astronomer have come to believe that these four planets are in resonance with each other.

In this case, the four planets orbit their star with a 1:2:4:8 resonance, meaning that each planet’s orbital period is in a nearly precise ratio with the others in the system. This is a relatively unique phenomena, one which inspired a Jason Wang – a graduate student from the Berkeley arm of the NASA-sponsored Nexus for Exoplanet System Science (NExSS) – to produce a video that illustrates their orbital dance.

Using images obtained by the W.M. Keck Observatory over a seven year period, Wang’s video provides a glimpse of these four exoplanets in motion. As you can see below, the central star is blacked out so that the light reflecting off of its planets can be seen. And while it does not show the planets completing a full orbital period (which would take decades and even centuries) it beautifully illustrates the resonance that exists between the star’s four planets.

As Jason Wang told Universe Today via email:

“The data was obtained over 7 years from one of the 10 meter Keck telescopes by a team of astronomers (Christian Marois, Quinn Konopacky, Bruce Macintosh, Travis Barman, and Ben Zuckerman). Christian reduced each of the 7 epochs of data, to make 7 frames of data. I then made a movie by using a motion interpolation to interpolate those 7 frames into 100 frames to get a smooth video so that it’s not choppy (as if we could observe them every month from Earth).”

The images of the four exoplanets were originally captured by Dr. Christian Marois of the National Research Council of Canada’s Herzberg Institute of Astrophysics. It was in 2008 that Marois and his colleagues discovered the first three of HR 8799’s planets – HR 8799 b, c and d – using direct imaging technique. At around the same time, a team from UC Berkeley announced the discovery of Fomalhaut b, also using direct imaging.

These planets were all determined to be gas giants of similar size and mass, with between 1.2 and 1.3 times the size of Jupiter, and 7 to 10 times its mass. At the time of their discovery, HR 8799 d was believed to be the closest planet to its star, at a distance of about 27 Astronomical Units (AUs) – while the other two orbit at distances of about 42 and 68 AUs, respectively.

Image of HR 8799 (left) taken by the HST in 1998, image processed to remove scattered starlight (center), and illustration of the planetary system (right). Credit: NASA/ESA/STScI/R. Soummer

It was only afterwards that the team realized the planets had already been observed in 1998. Back then, the Hubble Space Telescope’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) had obtained light from the system that indicated the presence of planets. However, this was not made clear until after a newly-developed image-processing technique had been installed. Hence, the “pre-discovery” went unnoticed.

Further observations in 2009 and 2010 revealed the existence of fourth planet – HR 8799 e – which had an orbit placing it inside the other three. Even so, this planet is fifteen times farther from its star than the Earth is from the Sun, which results in an orbital period of about 18,000 days (49 years). The others take around 112, 225, and 450 years (respectively) to complete an orbit of HR 8799.

Ultimately, Wang decided to produce the video (which was not his first), to illustrate how exciting the search for exoplanets can be. As he put it:

“I had written this motion interpolation algorithm for another exoplanet system, Beta Pictoris b, where we see one planet on an edge-on orbit looking like it’s diving into its star (it’s actually just circling in front of it). We wanted to do the same thing for HR 8799 to bring this system to life and share our excitement in directly imaging exoplanets. I think it’s quite amazing that we have the technology to watch other worlds orbit other stars.”

In addition, the video draws attention to a star system that presents some unique opportunities for exoplanet research. Since HR 8799 was the first multi-planetary system to be directly-imaged means that astronomers can directly observe the orbits of the four planets, observe their dynamical interactions, and determine how they came to their present-day configuration.

Astronomers will also be able to take spectra of these planet’s atmospheres to study their composition, and compare this to our own Solar System’s gas giants. And since the system is really quite young (just 40 million years old), it can tell us much about the planet-formation process. Last, but not least, their wide orbits (a necessity given their size) could mean the system is less than stable.

In the future, according to Wang, astronomers will be watching to see if any planets get ejected from the system. I don’t know about you, but I would consider a video that illustrates one of HR 8799’s gas giants getting booted out of its system would be pretty inspiring too!

Further Reading: NASA

Posted on by Matt Williams

Space Jellyfish Show Types Of Pulsar Wind Nebulas

Four-panel graphic showing the two pulsars, Geminga (upper left) and B0355+54 (upper right), observed by Chandra. Credit: NASA/JPL-Caltech/CXC/PSU/B.Posselt et al/N.Klingler et al/Nahks TrEhnl

Since they were first discovered in the late 1960s, pulsars have continued to fascinate astronomers. Even though thousands of these pulsing, spinning stars have been observed in the past five decades, there is much about them that continues to elude us. For instance, while some emit both radio and gamma ray pulses, others are restricted to either radio or gamma ray radiation.

However, thanks to a pair of studies from two international teams of astronomers, we may be getting closer to understanding why this is. Relying on data collected by the Chandra X-ray Observatory of two pulsars (Geminga and B0355+54), the teams was able to show how their emissions and the underlying structure of their nebulae (which resemble jellyfish) could be related.

These studies, “Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54” and “Geminga’s Puzzling Pulsar Wind Nebula” were published in The Astrophysical Journal. For both, the teams relied on x-ray data from the Chandra Observatory to examine the Geminga and B0355+54 pulsars and their associated pulsar wind nebulae (PWN).

An artist’s impression of an accreting X-ray millisecond pulsar. Credit: NASA/Goddard Space Flight Center/Dana Berry

Located 800 and 3400 light years from Earth (respectively), the Geminga and B0355+54 pulsars are quite similar. In addition to having similar rotational periods (5 times per second), they are also about the same age (~500 million years). However, Geminga emits only gamma-ray pulses while B0355+54 is one of the brightest known radio pulsars, but emits no observable gamma rays.

What’s more, their PWNs are structured quite differently. Based on composite images created using Chandra X-ray data and Spitzer infrared data, one resembles a jellyfish whose tendrils are relaxed while the other looks like a jellyfish that is closed and flexed. As Bettina Posselt – a senior research associate in the Department of Astronomy and Astrophysics at Penn State, and the lead author on the Geminga study – told Universe Today via email:

“The Chandra data resulted in two very different X-ray images of the pulsar wind nebulae around the pulsars Geminga and PSR B0355+54. While Geminga has a distinct three-tail structure, the image of PSR B0355+54 shows one broad tail with several substructures.”

In all likelihood, Geminga’s and B0355+54 tails are narrow jets emanating from the pulsar’s spin poles. These jets lie perpendicular to the donut-shaped disk (aka. a torus) that surrounds the pulsars equatorial regions. As Noel Klingler, a graduate student at the George Washington University and the author of the B0355+54 paper, told Universe Today via email:

“The interstellar medium (ISM) isn’t a perfect vacuum, so as both of these pulsars plow through space at hundreds of kilometers per second, the trace amount of gas in the ISM exerts pressure, thus pushing back/bending the pulsar wind nebulae behind the pulsars, as is shown in the images obtained by the Chandra X-ray Observatory.”

Their apparent structures appear to be due to their disposition relative to Earth. In Geminga’s case, the view of the torus is edge-on while the jets point out to the sides. In B0355+54’s case, the torus is seen face-on while the jets points both towards and away from Earth. From our vantage point, these jets look like they are on top of each other, which is what makes it look like it has a double tail. As Posselt describes it:

“Both structures can be explained with the same general model of pulsar wind nebulae. The reasons for the different images are (a) our viewing perspective, and (b) how fast and where to the pulsar is moving. In general, the observable structures of such pulsar wind nebulae can be described with an equatorial torus and polar jets. Torus and Jets can be affected (e.g., bent jets) by the “head wind” from the interstellar medium the pulsar is moving in. Depending on our viewing angle of the torus, jets and the movement of the pulsar, different pictures are detected by the Chandra X-ray observatory. Geminga is seen “from the side” (or edge-on with respect to the torus) with the jets roughly located in the plane of the sky  while for B0355+54 we look almost directly to one of the poles.”

This orientation could also help explain why the two pulsars appear to emit different types of electromagnetic radiation. Basically, the magnetic poles – which are close to their spin poles – are where a pulsar’s radio emissions are believed to come from. Meanwhile, gamma rays are believed to be emitted along a pulsar’s spin equator, where the torus is located.

“The images reveal that we see Geminga from edge-on (i.e., looking at its equator) because we see X-rays from particles launched into the two jets (which are initially aligned with the radio beams), which are pointed into the sky, and not at Earth,” said Klingler. “This explains why we only see Gamma-ray pulses from Geminga.  The images also indicate that we are looking at B0355+54 from a top-down perspective (i.e., above one of the poles, looking into the jets).  So as the pulsar rotates, the center of the radio beam sweeps across Earth, and we detect the pulses;  but the  gamma-rays are launched straight out from the pulsar’s equator, so we don’t see them from B0355.”

An all-sky view from the Fermi Gamma-ray Space Telescope, showing the position of Geminga in the Milky Way. Credit : NASA/DOE/International LAT Team.

“The geometrical constraints on each pulsar (where are the poles and the equator) from the pulsar wind nebulae help to explain findings regarding the radio and gamma-ray pulses of these two neutron stars,” said Posselt. “For example, Geminga appears radio-quiet (no strong radio pulses) because we don’t have a direct view to the poles and pulsed radio emission is thought to be generated in a region close to the poles. But Geminga shows strong gamma-ray pulsations, because these are not produced at the poles, but closer to the equatorial region.”

These observations were part of a larger campaign to study six pulsars that have been seen to emit gamma-rays. This campaign is being led by Roger Romani of Stanford University, with the collaboration of astronomers and researchers from GWU (Oleg Kargaltsev), Penn State University (George Pavlov), and Harvard University (Patrick Slane).

Not only are these studies shedding new light on the properties of pulsar wind nebulae, they also provide observational evidence to help astronomers create better theoretical models of pulsars. In addition, studies like these – which examine the geometry of pulsar magnetospheres – could allow astronomers to better estimate the total number of exploded stars in our galaxy.

By knowing the range of angles at which pulsars are detectable, they should be able to better estimate the amount that are not visible from Earth. Yet another way in which astronomers are working to find the celestial objects that could be lurking in humanity’s blind spots!

Further Reading: Chandra X-Ray Observatory

Posted on by Bob King

Carl Sagan’s Theory Of Early Mars Warming Gets New Attention

Credit and copyright: ESA/DLR/FU Berlin (G. Neukum)
Ah, the good old days. ESA’s Mars Express imaged Reull Vallis, a river-like structure believed to have formed when running water flowed in the distant Martian past, cuts a steep-sided channel on its way towards the floor of the Hellas basin. A thicker atmosphere that included methane and hydrogen in addition to carbon dioxide may have allowed liquid water to flow on Mars at different times in the past according to a new study. Credit and copyright: ESA/DLR/FU Berlin (G. Neukum)

Water. It’s always about the water when it comes to sizing up a planet’s potential to support life. Mars may possess some liquid water in the form of occasional salty flows down crater walls,  but most appears to be locked up in polar ice or hidden deep underground. Set a cup of the stuff out on a sunny Martian day today and depending on conditions, it could quickly freeze or simply bubble away to vapor in the planet’s ultra-thin atmosphere.

These rounded pebbles got their shapes after polished in a long-ago river in Gale Crater. They were discovered by Curiosity rover at the Hottah site. Credit: NASA/JPL-Caltech

Evidence of abundant liquid water in former flooded plains and sinuous river beds can be found nearly everywhere on Mars. NASA’s Curiosity rover has found mineral deposits that only form in liquid water and pebbles rounded by an ancient stream that once burbled across the floor of Gale Crater. And therein lies the paradox.  Water appears to have gushed willy-nilly across the Red Planet 3 to 4 billion years ago, so what’s up today?

Blame Mars’ wimpy atmosphere. Thicker, juicier air and the increase in atmospheric pressure that comes with it would keep the water in that cup stable. A thicker atmosphere would also seal in the heat, helping to keep the planet warm enough for liquid water to pool and flow.

Different ideas have been proposed to explain the putative thinning of the air including the loss of the planet’s magnetic field, which serves as a defense against the solar wind.

This figure shows a cross-section of the planet Mars revealing an inner, high density core buried deep within the interior. Magnetic field lines are drawn in blue, showing the global scale magnetic field associated with a dynamic core. Mars must have had such a field long ago, but today it’s not evident. Perhaps the energy source that powered the early dynamo shut down. Credit: NASA/JPL/GSFC

Convection currents within its molten nickel-iron core likely generated Mars’ original magnetic defenses. But sometime early in the planet’s history the currents stopped either because the core cooled or was disrupted by asteroid impacts. Without a churning core, the magnetic field withered, allowing the solar wind to strip away the atmosphere, molecule by molecule.


Solar wind eats away the Martian atmosphere

Measurements from NASA’s current MAVEN mission indicate that the solar wind strips away gas at a rate of about 100 grams (equivalent to roughly 1/4 pound) every second. “Like the theft of a few coins from a cash register every day, the loss becomes significant over time,” said Bruce Jakosky, MAVEN principal investigator.

This graph shows the percent amount of the five most abundant gases in the atmosphere of Mars, as measured by the  Sample Analysis at Mars (SAM) instrument suite on the Curiosity rover in October 2012. The season was early spring in Mars’ southern hemisphere. Credit: NASA/JPL-Caltech, SAM/GSFC

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) suggest a different, less cut-and-dried scenario. Based on their studies, early Mars may have been warmed now and again by a powerful greenhouse effect. In a paper published in Geophysical Research Letters, researchers found that interactions between methane, carbon dioxide and hydrogen in the early Martian atmosphere may have created warm periods when the planet could support liquid water on its surface.

The team first considered the effects of CO2, an obvious choice since it comprises 95% of Mars’ present day atmosphere and famously traps heat. But when you take into account that the Sun shone 30% fainter 4 billion years ago compared to today, CO2  alone couldn’t cut it.

“You can do climate calculations where you add CO2 and build up to hundreds of times the present day atmospheric pressure on Mars, and you still never get to temperatures that are even close to the melting point,” said Robin Wordsworth, assistant professor of environmental science and engineering at SEAS, and first author of the paper.

NASA’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. The breakdown of methane at Titan into hydrogen and oxygen may also have occurred on Mars. The addition of hydrogen in the company of methane and carbon dioxide would have created a powerful greenhouse gas mixture, significantly warming the planet. Credit: NASA/JPL-Caltech/Space Science Institute

Carbon dioxide isn’t the only gas capable of preventing heat from escaping into space. Methane or CH4 will do the job, too. Billions of years ago, when the planet was more geologically active, volcanoes could have tapped into deep sources of methane and released bursts of the gas into the Martian atmosphere. Similar to what happens on Saturn’s moon Titan, solar ultraviolet light would snap the molecule in two, liberating hydrogen gas in the process.

When Wordsworth and his team looked at what happens when methane, hydrogen and carbon dioxide collide and then interact with sunlight, they discovered that the combination strongly absorbed heat.

Carl Sagan, American astronomer and astronomy popularizer, first speculated that hydrogen warming could have been important on early Mars back in 1977, but this is the first time scientists have been able to calculate its greenhouse effect accurately. It is also the first time that methane has been shown to be an effective greenhouse gas on early Mars.

This awesome image of the Tharsis region of Mars taken by Mars Express shows several prominent shield volcanoes including the massive Olympus Mons (at left). Volcanoes, when they were active, could have released significant amounts of methane into Mars’ atmosphere. Click for a larger version. Credit: ESA

When you take methane into consideration, Mars may have had episodes of warmth based on geological activity associated with earthquakes and volcanoes. There have been at least three volcanic epochs during the planet’s history — 3.5 billion years ago (evidenced by lunar mare-like plains), 3 billion years ago (smaller shield volcanoes) and 1 to 2 billion years ago, when giant shield volcanoes such as Olympus Mons were active. So we have three potential methane bursts that could rejigger the atmosphere to allow for a mellower Mars.

The sheer size of Olympus Mons practically shouts massive eruptions over a long period of time. During the in-between times, hydrogen, a lightweight gas, would have continued to escape into space until replenished by the next geological upheaval.

“This research shows that the warming effects of both methane and hydrogen have been underestimated by a significant amount,” said Wordsworth. “We discovered that methane and hydrogen, and their interaction with carbon dioxide, were much better at warming early Mars than had previously been believed.”

I’m tickled that Carl Sagan walked this road 40 years ago. He always held out hope for life on Mars. Several months before he died in 1996, he recorded this:

” … maybe we’re on Mars because of the magnificent science that can be done there — the gates of the wonder world are opening in our time. Maybe we’re on Mars because we have to be, because there’s a deep nomadic impulse built into us by the evolutionary process, we come after all, from hunter gatherers, and for 99.9% of our tenure on Earth we’ve been wanderers. And, the next place to wander to, is Mars. But whatever the reason you’re on Mars is, I’m glad you’re there. And I wish I was with you.”

Posted on by David Dickinson

A Farewell to Plutoshine

Credit:
Looking back at an overexposed Charon and Plutoshine. Credit: NASA/JPL/New Horizons

Sometimes, its not the eye candy aspect of the image, but what it represents. A recent image of Pluto’s large moon Charon courtesy of New Horizons depicting what could only be termed ‘Plutoshine’ caught our eye. Looking like something from the grainy era of the early Space Age, we see a crescent Charon, hanging against a starry background…

So what, you say? Sure, the historic July 14th , 2015 flyby of New Horizons past Pluto and friends delivered images with much more pop and aesthetic appeal. But look closely, and you’ll see something both alien and familiar, something that no human eye has ever witnessed, yet you can see next week.

We’re talking about the reflected ‘Plutoshine‘ on the dark limb of Charon. This over-exposed image was snapped from over 160,000 kilometers distant by New Horizons’ Ralph/Multispectral imager looking back at Charon, post flyby. For context, that’s just shy of half the distance between the Earth and the Moon. “Bigger than Texas” (Cue Armageddon), Charon is about 1200 kilometers in diameter and 1/8th the mass of Pluto. Together, both form the only true binary (dwarf) planetary pair in the solar system, with the 1/80th Earth-Moon pair coming in at a very distant second.

Earthshine on the Moon. Credit: Dave Dickinson

We see reflected sunlight coming off of a gibbous Pluto which is just out of frame, light that left the Sun 4 hours ago and took less than a second to make the final Pluto-Charon-New Horizons bounce. You can see a similar phenomenon next week, as Earthshine or Ashen Light illuminates the otherwise dark nighttime side of the Earth’s Moon, fresh off of passing New phase this weekend. Snow and cloud cover turned Moonward can have an effect on how bright Earthshine appears. One ongoing study based out of the Big Bear Solar observatory in California named Project Earthshine seeks to characterize long-term climate variations looking at this very phenomenon.

The view on the evening of January 28th looking west at dusk. Credit: Stellarium.

Standing on Pluto, you’d see a 3.5 degree wide Charon, 7 times larger than our own Full Moon. Of course, you’d need to be standing in the right hemisphere, as Pluto and Charon are tidally locked, and keep the same face turned towards each other. It would be a dim view, as the Sun shines at -20 magnitude at 30 AU distant, much brighter than a Full Moon, but still over 600 times fainter than sunny Earth. Dim Plutoshine on the nightside of Charon would, however, be easily visible to the naked eye.

A small 6 cm instrument, Ralph images in the visual to near-infrared range. Ralph compliments New Horizons larger LORRI instrument, which has a diameter and very similar optical configuration to an amateur 8-inch Schmidt-Cassegrain telescope.

Charon as seen from Pluto. Credit: Starry Night.

Don’t look for Pluto now; it just passed solar conjunction on the far side of the Sun on January 7th, 2017. Pluto reaches opposition and favorable viewing for 2017 on July 10th, one of the 101 Astronomical Events for 2017 that you’ll find in our free e-book, out from Universe Today.

And for an encore, New Horizons will visit the 45 kilometer in diameter Kuiper Belt Object 2014 MU69 on New Year’s Day 2019. From there, New Horizons will most likely chronicle the environs of the the distant solar system, as it joins Pioneer 10 and 11 and Voyagers 1 and 2 as human built artifacts cast adrift along the galactic plane.

A pretty pair: Pluto and Charon. Credit: NASA/JPL/New Horizons

And to think, it has taken New Horizons about 18 months for all of its flyby data to trickle back to the Earth. Enjoy, as it’ll be a long time before we visit Pluto and friends again.

Posted on by Bob King

Rogue NASA, EPA, NPS Twitter Accounts Launched to Protest Trump Directives

Credit: Twitter
Twitter page of Rogue NASA. Credit: Twitter

Three federal agencies — the National Park Service, the EPA and now NASA — have allegedly launched unofficial “protest” accounts on Twitter in defiance of the Trump team’s directives to not blog, tweet or talk to the news media about climate changes issues. While it’s not unusual for a new administration to want to control the message, many bristle at what they see as an administration that wants to redefine and control scientific fact.

That brings us to these accounts. Are they really created by NASA and other government employees or are they the work of ticked off science advocates not connected to the agencies? In at least one case earlier this week in Badlands National Park, a former employee posted this unauthorized tweet:

“Today, the amount of carbon dioxide in the atmosphere is higher than at any time in the last 650,000 years.” The tweet was later removed.

The @RogueNASA Twitter account uses NASA’s logo — a no-no unless you have specific permission. The site describes itself as “the unofficial “Resistance” team of NASA. Not an official NASA account. Follow for science and climate news and facts. REAL NEWS, REAL FACTS.”

NASA’s very strict about how it’s logo is used. Under Media Usage Guidelines, here’s what the agency has to say:

“The NASA insignia logo (the blue “meatball” insignia), the retired NASA logotype (the red “worm” logo) and the NASA seal may not be used for any purpose without explicit permission. These images may not be used by persons who are not NASA employees or on products, publications or web pages that are not NASA-sponsored. These images may not be used to imply endorsement or support of any external organization, program, effort, or persons.”

AltEPA Twitter page. Credit: Twitter

Moreover, NASA reported that it had not given permission for another group or person to use its logo on the new account. While the sites may be legit and you and I sympathetic to the cause, exercise skepticism when poking around these accounts. Be cautious of opening up or downloading files the same way you’re careful with e-mail attachments. Take a look, participate, but be wary.

For your perusal, the current “alt science” sites I’m aware of are listed below. My hunch after looking at them is that it’s possible they may have been created by the same group of people. Whatever their origin, they’re quickly becoming very popular. As of Wednesday evening (Jan. 25), Rogue NASA has 209,000 followers; AltEPA 41,600 and 883,000 at AltUSNatParkService.

* AltUSNatParkService
* AltEPA
* Rogue NASA
* AltNASA

For more on the new administration and NASA, check out Nancy Atkinson’s story “Could NASA Be Muzzled Under Trump Administration?”

Posted on by Ken Kremer

NASA Webb Telescope Resumes Rigorous Vibration Qualification Tests

NASA engineers and technicians position the James Webb Space Telescope (inside a large tent) onto the shaker table used for vibration testing. Credits: NASA/Chris Gunn
NASA engineers and technicians position the James Webb Space Telescope (inside a large tent) onto the shaker table used for vibration testing. Credits: NASA/Chris Gunn

Engineers have resumed a series of critical and rigorous vibration qualification tests on NASA’s mammoth James Webb Space Telescope (JWST) at NASA’s Goddard Space Flight Center, in Greenbelt, Maryland to confirm its safety, integrity and readiness for the unforgiving environment of space flight, after pausing due to a testing ‘anomaly’ detected in early December 2016.

The vibration tests are conducted by the team on a shaker table at Goddard to ensure Webb’s worthiness and that it will survive the rough and rumbling ride experienced during the thunderous rocket launch to the heavens slated for late 2018.

“Testing on the ground is critical to proving a spacecraft is safe to launch,” said Lee Feinberg, an engineer and James Webb Space Telescope Optical Telescope Element Manager at Goddard, in a statement.

“The Webb telescope is the most dynamically complicated article of space hardware that we’ve ever tested.”

The 18-segment gold coated primary mirror of NASA’s James Webb Space Telescope is raised into vertical alignment in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on Nov. 2, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com

Testing of the gargantuan Webb Telescope had ground to a halt after a brief scare in early December when technicians initially detected “anomalous readings” that raised potential concerns about the observatories structural integrity partway through a preplanned series of vibration tests.

“On December 3, 2016, vibration testing automatically shut down early due to some sensor readings that exceeded predicted levels,” officials said.

Thereafter, engineers and technicians carried out a new batch of intensive inspections of the observatory’s structure during December.

Shortly before Christmas, NASA announced on Dec. 23 that JWST was deemed “sound” and apparently unscathed after engineers conducted both “visual and ultrasonic examinations” at NASA’s Goddard Space Flight Center in Maryland. Officials said the telescope was found to be safe at this point with “no visible signs of damage.”

As it turned out the culprit of the sensor anomaly was the many “tie-down … restraint mechanisms ” that hold the telescope in place.

“After a thorough investigation, the James Webb Space Telescope team at NASA Goddard determined that the cause was extremely small motions of the numerous tie-downs or “launch restraint mechanisms” that keep one of the telescope’s mirror wings folded-up for launch,” NASA officials explained in a statement.

Furthermore engineers revealingly discovered that “the ground vibration test itself is more severe than the launch vibration environment.”

Technicians work on the James Webb Space Telescope in the massive clean room at NASA’s Goddard Space Flight Center, Greenbelt, Maryland, on Nov. 2, 2016, as the completed golden primary mirror and observatory structure stands gloriously vertical on a work stand, reflecting incoming light from the area and observation deck. Credit: Ken Kremer/kenkremer.com

NASA reported today (Jan. 25) that the testing resumed last week at the point where it had been paused. Furthermore the testing was completed along the first of three axis.

“In-depth analysis of the test sensor data and detailed computer simulations confirmed that the input vibration was strong enough and the resonance of the telescope high enough at specific vibration frequencies to generate these tiny motions. Now that we understand how it happened, we have implemented changes to the test profile to prevent it from happening again,” explained Feinberg.

“We have learned valuable lessons that will be applied to the final pre-launch tests of Webb at the observatory level once it is fully assembled in 2018. Fortunately, by learning these lessons early, we’ve been able to add diagnostic tests that let us show how the ground vibration test itself is more severe than the launch vibration environment in a way that can give us confidence that the launch itself will be fully successful.”

The next step is to resume and complete shaking the telescope in the other two axis, or “two directions to show that it can withstand vibrations in all three dimensions.”

“This was a great team effort between the NASA Goddard team, Northrop Grumman, Orbital ATK, Ball Aerospace, the European Space Agency, and Arianespace,” Feinberg said. “We can now proceed with the rest of the planned tests of the telescope and instruments.”

NASA’s James Webb Space Telescope is the most powerful space telescope ever built and is the scientific successor to the phenomenally successful Hubble Space Telescope (HST). The mammoth 6.5 meter diameter primary mirror has enough light gathering capability to scan back over 13.5 billion years and see the formation of the first stars and galaxies in the early universe.

The Webb telescope will launch on an ESA Ariane V booster from the Guiana Space Center in Kourou, French Guiana in 2018.

But Webb and its 18 segment “golden” primary mirror have to be carefully folded up to fit inside the nosecone of the Ariane V booster.

“Due to its immense size, Webb has to be folded-up for launch and then unfolded in space. Prior generations of telescopes relied on rigid, non-moving structures for their stability. Because our mirror is larger than the rocket fairing we needed structures folded for launch and moved once we’re out of Earth’s atmosphere. Webb is the first time we’re building for both stability and mobility.” Feinberg said.

“This means that JWST testing is very unique, complex, and challenging.”

View showing actual flight structure of mirror backplane unit for NASA’s James Webb Space Telescope (JWST) that holds 18 segment primary mirror array and secondary mirror mount at front, in stowed-for-launch configuration. JWST is being assembled here by technicians inside the world’s largest cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.com

The environmental testing is being done at Goddard before shipping the huge structure to NASA’s Johnson Space Center in February 2017 for further ultra low temperature testing in the cryovac thermal vacuum chamber.

The 6.5 meter diameter ‘golden’ primary mirror is comprised of 18 hexagonal segments – looking honeycomb-like in appearance.

And it’s just mesmerizing to gaze at – as I had the opportunity to do on a few occasions at Goddard this past year – standing vertically in November and seated horizontally in May.

Each of the 18 hexagonal-shaped primary mirror segments measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). They are made of beryllium, gold coated and about the size of a coffee table.

All 18 gold coated primary mirrors of NASA’s James Webb Space Telescope are seen fully unveiled after removal of protective covers installed onto the backplane structure, as technicians work inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com

The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

Webb is designed to look at the first light of the Universe and will be able to peer back in time to when the first stars and first galaxies were forming. It will also study the history of our universe and the formation of our solar system as well as other solar systems and exoplanets, some of which may be capable of supporting life on planets similar to Earth.

Gold coated primary mirrors newly exposed on spacecraft structure of NASA’s James Webb Space Telescope inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. Aft optics subsystem stands upright at center of 18 mirror segments between stowed secondary mirror mount booms. Credit: Ken Kremer/kenkremer.com

Watch this space for my ongoing reports on JWST mirrors, science, construction and testing.

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

Ken Kremer

James Webb Space Telescope. Image credit: NASA/JPL
Posted on by Matt Williams

Galactic Stripping Mystery Uncovered

Artist’s impression showing the increasing effect of ram-pressure stripping in removing gas from galaxies, sending them to an early death. Credit: ICRAR/NASA/ESA/Hubble Heritage Team (STScI/AURA)

It’s what you might call a case of galactic homicide (or “galacticide”). All over the known Universe, satellite galaxies are slowly being stripped of their lifeblood – i.e. their gases. This process is responsible for halting the formation of new stars, and therefore condemning these galaxies to a relatively quick death (by cosmological standards). And for some time, astronomers have been searching for the potential culprit.

But according to a new study by a team of international researchers from the International Center for Radio Astronomy Research (ICRAR) in Australia, the answer may have to do with the hot gas galactic clusters routinely pass through. According to their study, which appeared recently in The Monthly Notices of the Royal Astronomical Society, this mechanism may be responsible for the slow death we are seeing out there.

This process is known as “ram-pressure stripping“, which occurs when the force created by the passage of galaxies through the hot plasma that lies between them is strong enough that it is able to overcome the gravitational pull of those galaxies. At this point, they lose gas, much in the same way that a planet’s atmosphere can be slowly stripped away by the effects of Solar wind.

‘Radio color’ view of the sky above the Murchison Widefield Array radio telescope, part of the International Center for Radio Astronomy Research (ICRAC). Credit: Natasha Hurley-Walker (ICRAR/Curtin)/Dr John Goldsmith/Celestial Visions.

For the sake of their study, titled “Cold gas stripping in satellite galaxies: from pairs to clusters“, the team relied on data obtained by the Sloan Digital Sky Survey and the Arecibo Legacy Fast (ALFA) survey. While the SDSS provided multi-wavelength data on 10,600 satellite galaxies in the known Universe, ALFA provided data on the amount of neutral atomic hydrogen they contained.

By measuring the amount of stripping that took place within each, they deduced that the extent to which a galaxy was stripped of its essential gases had much to do with the mass of its dark matter halo. For some time, astronomers have believed that galaxies are embedded in clouds of this invisible mass, which is believed to make up 27% of the known Universe.

As Toby Brown – a researcher from the Center for Astrophysics and Supercomputing at the Swinburne University of Technology and the lead author on the paper – explained:

“During their lifetimes, galaxies can inhabit halos of different sizes, ranging from masses typical of our own Milky Way to halos thousands of times more massive. As galaxies fall through these larger halos, the superheated intergalactic plasma between them removes their gas in a fast-acting process called ram-pressure stripping. You can think of it like a giant cosmic broom that comes through and physically sweeps the gas from the galaxies.”

The Arecibo Observatory in Puerto Rico, where the Arecibo Legacy Fast ALFA Survey is conducted. Credit: egg.astro.cornell.edu

This stripping is what deprives satellites galaxies of their ability to form new stars, which ensures that the stars they have enter their red giant phase. This process, which results in a galaxy populated by cooler stars, makes them that much harder to see in visible light (though still detectable in the infrared band). Quietly, but quickly, these galaxies become cold, dark, and fade away.

Already, astronomers were aware of the effects of ram-pressure stripping of galaxies in clusters, which boast the largest dark matter halos found in the Universe. But thanks to their study, they are now aware that it can affect satellite galaxies as well. Ultimately, this shows that the process of ram-pressure stripping is more prevalent than previously thought.

As Dr. Barbara Catinella, an ICRAR researcher and co-author on the study, put it:

“Most galaxies in the Universe live in these groups of between two and a hundred galaxies. We’ve found this removal of gas by stripping is potentially the dominant way galaxies are quenched by their surroundings, meaning their gas is removed and star formation shuts down.”

Another major way in which galaxies die is known as “strangulation”, which occurs when a galaxy’s gas is consumed faster than it can be replenished. However, compared to ram-pressure stripping, this process is very gradual, taking billions of years rather than just tens of millions – very fast on a cosmological time scale. Also, this process is more akin to a galaxy suffering from famine after outstripping its food source, rather than homicide.

Another cosmological mystery solved, and one that has crime-drama implications no less!

Further Reading: Royal Astronomical Society, MNRAS

Posted on by Matt Williams

Japan Becomes A Military Space Player With Latest Launch

JAXA's H-IIA Launch Vehicle taking off from the Tanegashima Space Center. Credit: Wikipedia Commons/NARITA Masahiro

The Japanese Aerospace Exploration Agency (JAXA) has accomplished some impressive things over the years. Between 2003 (when it was formed) and 2016, the agency has launched multiple satellites – ranging from x-ray and infrared astronomy to lunar and Venus atmosphere exploration probes – and overseen Japan’s participation in the International Space Station.

But in what is an historic mission – and a potentially controversial one – JAXA recently launched the first of three X-band defense communication satellites into orbit. By giving the Japanese Self-Defense Forces the ability to relay communications and commands to its armed forces, this satellite (known as DSN 2) represents an expansion of Japan’s military capability.

The launch took place on January 24th at 4:44 pm Japan Standard Time (JST) – or 0744 Greenwich Mean Time (GMT) – with the launch of a H-IIA rocket from Tanegashima Space Center. This was the thirty-second successful flight of the launch vehicle, and the mission was completed with the deployment of the satellite in Low-Earth Orbit – 35,000 km; 22,000 mi above the surface of the Earth.

Artist’s concept of a Japanese X-band military communications satellite. Credit: Japanese Ministry of Defense

Shortly after the completion of the mission, JAXA issued a press release stating the following:

“At 4:44 p.m., (Japan Standard Time, JST) January 24, Mitsubishi Heavy Industries, Ltd. and JAXA launched the H-IIA Launch Vehicle No. 32 with X-band defense communication satellite-2* on board. The launch and the separation of the satellite proceeded according to schedule. Mitsubishi Heavy Industries, Ltd. and JAXA express appreciation for the support in behalf of the successful launch. At the time of the launch the weather was fine, at 9 degrees Celsius, and the wind speed was 7.1 meters/second from the NW.”

This launch is part of a $1.1 billion program by the Japanese Defense Ministry to develop X-band satellite communications for the Japan Self-Defense Forces (JSDF). With the overall goal of deploying three x-band relay satellites into geostationary orbit, its intended purpose is to reduce the reliance of Japan’s military (and those of its allies) on commercial and international communications providers.

While this may seem like a sound strategy, it is a potential source of controversy in that it may skirt the edge of what is constitutionally permitted in Japan. In short, deploying military satellites is something that may be in violation of Japan’s post-war agreements, which the nation committed to as part of its surrender to the Allies. This includes forbidding the use of military force as a means of solving international disputes.

An H-2A rocket, Japan’s primary large-scale launch vehicle. Credit: JAXA

It also included placing limitations on its Self-Defense Forces so they would not be capable of independent military action. As is stated in Article 9 of the Constitution of Japan (passed in 1947):

“(1) Aspiring sincerely to an international peace based on justice and order, the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes.
(2) In order to accomplish the aim of the preceding paragraph, land, sea, and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized.”

However, since 2014, the Japanese government has sought to reinterpret Article 9 of the constitution, claiming that it allows the JSDF the freedom to defend other allies in case of war. This move has largely been in response to mounting tensions with North Korea over its development of nuclear weapons, as well as disputes with China over issues of sovereignty in the South China Sea.

This interpretation has been the official line of the Japanese Diet since 2015, as part of a series of measures that would allow the JSDF to provide material support to allies engaged in combat internationally. This justification, which claims that Japan and its allies would be endangered otherwise, has been endorsed by the United States. However, to some observers, it may very well be interpreted as an attempt by Japan to re-militarize.

In the coming weeks, the DSN 2 spacecraft will use its on-board engine to position itself in geostationary orbit, roughly 35,800 km (22,300 mi) above the equator. Once there, it will commence a final round of in-orbit testing before commencing its 15-year term of service.

Further Reading: Spaceflight Now

Posted on by Matt Williams

Here’s the Highest Resolution Map of Pluto We’ll Get from New Horizons

Color mosaic map of Pluto's surface, created from the New Horizons many photographs. Credit: NASA/JHUAPL/SwRI

On July 14th, 2015, the New Horizons mission made history by conducting the first flyby of Pluto. This represented the culmination of a nine year journey, which began on January 19th, 2006 – when the spacecraft was launched from the Cape Canaveral Air Force Station. And before the mission is complete, NASA hopes to send the spacecraft to investigate objects in the Kuiper Belt as well.

To mark the 11th anniversary of the spacecraft’s launch, members of the New Horizons team took part in panel a discussion hosted by the Johns Hopkins University Applied Physics Laboratory (JHUAPL) located in Laurel, Maryland. The event was broadcasted on Facebook Live, and consisted of team members speaking about the highlights of the mission and what lies ahead for the NASA spacecraft.

The live panel discussion took place on Thursday, Sept. 19th at 4 p.m. EST, and included Jim Green and Alan Stern – the director the Planetary Science Division at NASA and the principle investigator (PI) of the New Horizons mission, respectively. Also in attendance was Glen Fountain and Helene Winters, New Horizons‘ project managers; and Kelsi Singer, the New Horizons co-investigator.

Artist’s concept of the New Horizons spacecraft encountering a Kuiper Belt object, part of an extended mission after the spacecraft’s July 2015 Pluto flyby. Credits: NASA/JHUAPL/SwRI

In the course of the event, the panel members responded to questions and shared stories about the mission’s greatest accomplishments. Among them were the many, many high-resolution photographs taken by the spacecraft’s Ralph and Long Range Reconnaissance Imager (LORRI) cameras. In addition to providing detailing images of Pluto’s surface features, they also allowed for the creation of the very first detailed map of Pluto.

Though Pluto is not officially designated as a planet anymore – ever since the XXVIth General Assembly of the International Astronomical Union, where Pluto was designated as a “dwarf planet” – many members of the team still consider it to be the ninth planet of the Solar System. Because of this, New Horizons‘ historic flyby was of particular significance.

As Principle Investigator Alan Stern – from the Southwestern Research Institute (SwRI) – explained in an interview with Inverse, the first phase of humanity’s investigation of the Solar System is now complete. “What we did was we provided the capstone to the initial exploration of the planets,” he said. “All nine have been explored with New Horizons finishing that task.”

Other significant discoveries made by the New Horizons mission include Pluto’s famous heart-shaped terrain – aka.  Sputnik Planum. This region turned out to be a young, icy plain that contains water ice flows adrift on a “sea” of frozen nitrogen. And then there was the discovery of the large mountain and possible cryovolcano located at the tip of the plain – named Tombaugh Regio, (in honor of Pluto’s discovered, Clyde Tombaugh).

New Horizons path from the inner Solar System to Pluto and the Kuiper Belt. Credit: NASA/JHUAPL

The mission also revealed further evidence of geological activity and cryovolcanism, the presence of hyrdocarbon clouds on Pluto, and conducted the very first measurements of how Pluto interacts with solar wind. All told, over 50 gigabits of data were collected by New Horizons during its encounter and flyby with Pluto. And the detailed map which resulted from it did a good job of capturing all this complexity and diversity. As Stern explained:

“That really blew away our expectations. We did not think that a planet the size of North America could be as complex as Mars or even Earth. It’s just tons of eye candy. This color map is the highest resolution we will see until another spacecraft goes back to Pluto.”

After making its historic flyby of Pluto, the New Horizons team requested that the mission receive an extension to 2021 so that it could explore Kuiper Belt Objects (KBOs). This extension was granted, and for the first part of the Kuiper Belt Extended Mission (KEM), the spacecraft will perform a close flyby of the object known as 2014 MU69.

This remote KBO – which is estimated to be between 25 – 45 km (16-28 mi) in diameter – was one of two objects identified as potential targets for research, and the one recommended by the New Horizons team. The flyby, which is expected to take place in January of 2019, will involve the spacecraft taking a series of photographs on approach, as well as some pictures of the object’s surface once it gets closer.

Before the extension ends in 2021, it will continue to send back information on the gas, dust and plasma conditions in the Kuiper Belt. Clearly, we are not finished with the New Horizons mission, and it is not finished with us!

To check out footage from the live-streamed event, head on over to the New Horizons Facebook page.

Further Reading: NASA

Posted on by Bob King

How to See the Space Station Fly in Front of the Moon

A beautiful ISS transit on June 19 2015 recorded at Biscarrosse, France. Credit: David Duarte
What strange creature is this flitting across the Moon? Several members of the European Space Agency’s Astronomy Center captured these views of the International Space Station near Madrid, Spain on January 14 as it flew or transited in front of the full moon. Credit: Michel Breitfellner, Manuel Castillo, Abel de Burgos and Miguel Perez Ayucar / ESA

One-one thou… That’s how long it takes for the International Space Station, traveling at over 17,000 mph (27,300 kph), to cross the face of the Full Moon. Only about a half second! To see it with your own eyes, you need to know exactly when and where to look. Full Moon is best, since it’s the biggest the moon can appear, but anything from a half-moon up and up will do.

The photo above was made by superimposing 13 separate images of the ISS passing in front of the Moon into one. Once the team knew when the pass would happen, they used a digital camera to fire a burst of exposures, capturing multiple moments of the silhouetted spacecraft.


The ISS transits the Full Moon in May 2016

The ISS is the largest structure in orbit, spanning the size of a football field, but at 250 miles (400 km) altitude, it only appears as big as a modest lunar crater. While taking a photo sequence demands careful planning, seeing a pass is bit easier. As you’d suspect, the chances of the space station lining up exactly with a small target like the Moon from any particular location is small. But the ISS Transit Finder makes the job simple.

This is a screen grab from the homepage of Bartosz Wojczy?ski’s most useful ISS Transit Finder. Credit: Bartosz Wojczy?ski

Click on the link and fill in your local latitude, longitude and altitude or select from the Google maps link shown. You can always find your precise latitude and longitude at NASA’s Latitude/Longitude Finder  and altitude at Google Maps Find Altitude. Next, set the time span of your Moon transit search (up to one month from the current date) and then how far you’re willing to drive to see the ISS fly in front of the Moon.

When you click Calculate, you’ll get a list of events with little diagrams showing where the ISS will pass in relation to the Moon and sun (yes, the calculator also does solar disk crossings!) from your location. Notice that most of the passes will be near misses. However, if you click on the Show on Map link, you’ll get a ground track of exactly where you will need to travel to see it squarely cross Moon or Sun. Times shown are your local time, not Universal or UT.

A beautiful ISS transit on June 19 2015 recorded at Biscarrosse, France. The photographer used CalSky, another excellent satellite site, to prepare a week in advance of the event. This composite image was made with a Canon EOS 60D. Notice how bright the space station appears against the moon due to the lower-angled lighting across the lunar landscape at crescent phase compared to full, when the ISS appears in silhouette. Credit: David Duarte

The map also includes Recalculate for this location link. Clicking that will show you a sketch of the ISS’ predicted path across the Moon from the centerline location along with other details. I checked my city, and while there are no lunar transits for the next month, there’s a very nice solar one visible just a few miles from my home on Feb. 8. Remember to use a safe solar filter if you plan on viewing one of these!

The ISS transits the Sun on May 3, 2016. Click for details on how the photo was taken. Credit: Szabolcs Nagy

While you might attempt to see a transit of the ISS in binoculars, your best bet is with a telescope. Nothing fancy required, just about any size will do so long as it magnifies at least 30x to 40x. Timing is crucial. Like an occultation, when the moon hides a background star in an instant, you want to be on time and 100% present.

Make sure you’re set up and focused on the moon or sun (with filter) at least 5 minutes beforehand. Keep your cellphone handy. I’ve found the time displayed at least on my phone to be accurate. One minute before the anticipated transit, glue your eye to the eyepiece, relax and wait for the flyby. Expect something like a bird in silhouette to make a swift dash across the moon’s face. The video above will help you anticipate what to expect.

The next lunar transit nearest my home is an hour and a half away in the small town of Biwabik, Minn. according to the ISS Transit Finder. On Jan. 30 at 8:00:08 p.m local time, the ISS will cross the crescent moon from there. Once you know the time of the prediction and the exact latitude and longitude of the location (all information shown in the info box on the map using the ISS Transit Finder), you can turn on the satellites feature in the free Stellarium program (stellarium.org), select the ISS and create a simulated, detailed path. Created with Stellarium

Even if you never go to the trouble of identifying a “direct hit”, you can still use the transit finder to compile a list of cool lunar close approaches that would make for great photos with just a camera and tripod.

The Transit Finder isn’t the only way to predict ISS flybys. Some observers also use the excellent satellite site, CalSky. Once you tell it your location, select the Lunar/Solar Disk Crossings and Occultations link for lots of information including times, diagrams of crossings, ground tracks and more.

I use Stellarium (above) to make nifty simulated paths and show me where the Moon will be in the sky at the time of the transit. When you’ve downloaded the free program, get the latest satellite orbital elements this way:

* Move you cursor to the lower left of the window and select the Configuration box
* Click the Plugins tab and scroll down to Satellites and click Configure and then Update
* Hover the cursor at the bottom of the screen for a visual menu. Slide over to the satellite icon and click it once for Satellite hints. The ISS will now be active.
* Set the clock and location (lower left again) for the precise time and location, then do a search for the Moon, and you’ll see the ISS path.

There you have it — lots of options. Or you can simply use the Transit Finder and call it a day! I hope you’ll soon be in the right place at the right time to see the space station pass in front of the Moon. Checking my usual haunts, I see that the space station will be returning next weekend (Jan. 27) to begin an approximately 3-week run of easily viewable evening passes.