James Webb Space Telescope Takes The Gloves Off

Behold, the mighty primary mirror of the James Webb Space Telescope, in all its gleaming glory! Image: NASA/Chris Gunn — The primary mirror of the James Webb Space Telescope, in all its gleaming glory! Image: NASA/Chris Gunn

The James Webb Space Telescope (JWST) isn’t even operational yet, and already its gleaming golden mirror has reached iconic status. It’s segmented mirror is reminiscent of an insect eye, and once that eye is unfolded at its eventual stationary location at L2, the JWST will give humanity its best view of the Universe yet. Now, NASA has unveiled the JWST’s mirrors in a clean room at the Goddard Space Flight Centre, giving us a great look at what the telescope will look like when it’s operational.

Even if you didn’t know anything about the JWST, its capabilities, or its torturous path to finally being built, you would still look at it and be impressed. It’s obviously a highly technological, highly engineered, one of a kind object. In fact, you could be forgiven for mistaking it for a piece of modern art. (I’ve seen less appealing modern art, have you?)

The fact that the JWST will outperform its predecessor, the Hubble, is a well-known fact. After all, the Hubble is pretty long in the tooth now. But how exactly it will outperform the Hubble, and what the JWST’s mission objectives are, is less well-known. It’s worth it to take a look at the objectives of the JWST, again, and re-visit the enthusiasm that has surrounded this mission since its inception.

The James Webb Space Telescope in the clean room at the Goddard Space Flight Center. Image: NASA/Chris Gunn

NASA groups JWST’s science objectives into four areas:

infrared vision that acts like a time-machine, giving us a look at the first stars and galaxies to form in the Universe, over 13 billion years ago.
a comparative study of the stately spiral and elliptical galaxies of our age with the faintest, earliest galaxies to form in the Universe.
a probing gaze through clouds of dust, to watch stars and planets being born.
a look at extrasolar planets, and their atmospheres, keeping an eye out for biomarkers.

That is an impressive list, even in an age where people take technological and scientific progress for granted. But alongside these noble objectives, there will no doubt be some surprises. Guessing what those surprises might be is a bit of a fool’s errand, but this is the internet, so let’s dare to be foolish.

We have an idea that abiogenesis on Earth happened fairly quickly, but we have nothing to compare it to. Will we learn enough about exoplanets and their atmospheres to shed some light on conditions needed for life to happen? It’s a stretch, but who knows?

We have an understanding of the expansion of the Universe, and it’s backed up by pretty solid evidence. Will we learn something surprising about this? Or something that sheds some light on Dark Matter and Dark Energy, and their role in the early Universe?

Or will there be surprising findings in the area of planetary and stellar formation? The capability to look deeply into dust clouds should certainly reveal things previously unseen, but only guessed at.

Of course, not everything needs to be surprising to be exciting. Evidence that supports and fine tunes current theories is also intriguing. And the James Webb should deliver a boatload of evidence.

There’s no question that the JWST will outdo the Hubble in the science department. But for a generation or two of people, the Hubble will always have a special place. It drew many of us in, with its breathtaking pictures of nebulae and other objects, its famous Deep Field study, and, of course, its science. It was probably the first telescope to gain celebrity status.

The James Webb will probably never gain the social status that the Hubble gained. It’s kind of like the Beatles, there can only be one ‘first of its kind.’ But the JWST will be much more powerful, and will reveal to us a lot that has been hidden.

The JWST will be a grand technological accomplishment, if all goes well and it makes it to L2 and is fully functional. Its ability to look deeply into dust clouds, and to look back in time, to the early days of the Universe, make it a potent scientific tool.

And if engineering can figure out a way to reverse the polarity in the warp core without it going crit, we should be able to fire a beam of tachyon anti-matter neutrinos and de-cloak a Romulan Warbird at a distance of 3 AUs. Not bad for something Congress threatened to cancel!

April 27, 2016May 5, 2016 by Evan Gough

New Highest Resolution Images Of Long-Lost Beagle 2 Lander

On the left are original photos from NASA's Mars Reconnaissance Orbiter. On the right are sharper photos of the same, created by stacking matching photos on top of one another. Image: NASA/JPL-Caltech/Univ. of Arizona/Yu Tao et al/University College London.

We like to focus on successful space missions and celebrate what those successes add to our knowledge. But, obviously, not all missions are completely successful. And since some missions are at such huge distances from Earth, their fate can remain a mystery.

This was true of the Beagle 2 Lander, until recently.

The Beagle 2 was a UK contribution to the ESA’s Mars Express mission, launched in 2003. Mars Express consisted of two components; the Mars Express Orbiter and the Beagle 2 Lander. The mission arrived at Mars in December 2003, when the Beagle 2 separated from the orbiter and landed on the Martian surface.

Beagle 2’s destination was Isidis Planitia, a vast sedimentary basin. Beagle 2 was supposed to operate for 180 days, with a possible extension up to one Martian year. But the ESA was unable to contact the lander after several attempts, and in February 2004, the ESA declared the mission lost.

The Beagle 2, named after the ship that Darwin took on his famous voyage, had some solid science goals in mind. It was going to study the geology, mineralogy, and the geochemistry of the landing site, and also the physical properties of the atmosphere and Mars’ surface. It was also going to study the Martian meteorology and climate, and search for biosignatures. But all that was lost.

There was lots of conjecture, but the Beagle 2’s fate was a mystery.

Now, thanks to a new method of ‘stacking and matching’ photos of the Martian surface, which results in higher resolution images than previously possible, the likely fate of the Beagle 2 is known. It appears that the spacecraft landed softly as planned, but that solar panels failed to deploy properly. This not only starved the lander of electrical power, but blocked the craft’s antenna from functioning. This is why no signal was ever received from Beagle 2.

This is a zoomed in image of the Beagle 2 on Mars, with a to-scale sketch of the Beagle 2 super-imposed beside it. Credit: NASA/JPL-Caltech/Univ. of Arizona/Yu Tao et al/University College London/University of Leicester

It took quite a bit of sleuthing to find the Beagle 2. The MRO has used its High Resolution Imaging Science Experiment (HiRise) camera to search for other craft on the surface of Mars, but the Beagle 2 was harder to find. It never sent even a brief signal after touchdown, which would have made it much easier to locate.

Adding to the difficulty is the huge landing area the Beagle 2 had. Beagle 2’s landing site at the time of its launch was an ellipse 170 km by 100 km in the Isidis Planitia. That’s an enormous area in which to locate a spacecraft that’s less than a few meters across once deployed, with a camera that has an image scale of about 0.2m, (10 inches).

The MRO has been using its HiRise to look for Beagle 2 since it was lost. As it went about the business of its science objectives, it captured occasional images of the Beagle 2’s landing site. Eventually, the lander was identified by Michael Croon, a former member of the ESA’s Mars Express Orbiter team. In HiRise images from February 2013 and June 2014, Croon found visual evidence of the lander and its entry and descent components.

The puzzling thing was that the image seemed to shift around in different photos. This could be because the lander deployed its solar panels like flower petals arranged around the center. The panels will reflect light differently in different lighting conditions, which could make the lander appear to change location in subsequent photos. If Beagle 2 is sitting on an uneven surface, that could add to the illusion.

The HiRise images are consistent with the idea that the panels failed to deploy, and that also makes sense if the panels blocked the antenna from operating. It’s also possible that the sun glinting off the panels only makes it appear that not all of them opened.

A replica of the Beagle 2 lander at the London Science Museum. Image: By user:geni - Photo by user:geni, GFDL, https://commons.wikimedia.org/w/index.php?curid=5258554 — A replica of the Beagle 2 lander at the London Science Museum. Image: By user:geni – Photo by user:geni, GFDL, https://commons.wikimedia.org/w/index.php?curid=5258554

But what’s bad news for Beagle 2 is good news for the human endeavour to study Mars. The new technique of combining images of the surface of Mars yields photos with 5 times the resolution that MRO can provide. This will make selecting landing sites for future missions much easier, and will also contribute to the science objectives of the MRO itself.

These two images show the power of the new high-resolution imaging technique. The top shows two original images, on the left a rock field, and on the right, an area containing tracks left by the Spirit rover. Image: Credit: NASA/JPL-Caltech/Univ. of Arizona/Yu Tao et al/University College London

The Mars Express Orbiter is still in operation above Mars, and has been for over 12 years. Among its achievements are the detection of water ice in Mars’ South Polar cap and the discovery of methane in the atmosphere of Mars. The orbiter also performed the closest-ever flyby of Mars’ moon Phobos.

April 26, 2016May 5, 2016 by Evan Gough

Bayesian Analysis Rains On Exoplanet Life Parade

An exoplanet seen from its moon (artist's impression). Via the IAU.

Is there life on other planets, somewhere in this enormous Universe? That’s probably the most compelling question we can ask. A lot of space science and space missions are pointed directly at that question.

The Kepler mission is designed to find exoplanets, which are planets orbiting other stars. More specifically, its aim is to find planets situated in the habitable zone around their star. And it’s done so. The Kepler mission has found 297 confirmed and candidate planets that are likely in the habitable zone of their star, and it’s only looked at a tiny patch of the sky.

But we don’t know if any of them harbour life, or if Mars ever did, or if anywhere ever did. We just don’t know. But since the question of life elsewhere in the Universe is so compelling, it’s driven people with intellectual curiosity to try and compute the likelihood of life on other planets.

One of the main ways people have tried to understand if life is prevalent in the Universe is through the Drake Equation, named after Dr. Frank Drake. He tried to come up with a way to compute the probability of the existence of other civilizations. The Drake Equation is a mainstay of the conversation around the existence of life in the Universe.

The Drake Equation is a way to calculate the probability of extraterrestrial civilizations in the Milky Way that were technologically advanced to communicate. When it was created in 1961, Drake himself explained that it was really just a way of starting a conversation about extraterrestrial civilizations, rather than a definitive calculation. Still, the equation is the starting point for a lot of conversations.

But the problem with the Drake equation, and with all of our attempts to understand the likelihood of life starting on other planets, is that we only have the Earth to go by. It seems like life on Earth started pretty early, and has been around for a long time. With that in mind, people have looked out into the Universe, estimated the number of planets in habitable zones, and concluded that life must be present, and even plentiful, in the Universe.

But we really only know two things: First, life on Earth began a few hundred million years after the planet was formed, when it was sufficiently cool and when there was liquid water. The second thing that we know is that a few billions of years after life started, creatures appeared which were sufficiently intelligent enough to wonder about life.

In 2012, two scientists published a paper which reminded us of this fact. David Spiegel, from Princeton University, and Edwin Turner, from the University of Tokyo, conducted what’s called a Bayesian analysis on how our understanding of the early emergence of life on Earth affects our understanding of the existence of life elsewhere.

A Bayesian analysis is a complicated matter for non-specialists, but in this paper it’s used to separate out the influence of data, and the influence of our prior beliefs, when estimating the probability of life on other worlds. What the two researchers concluded is that our prior beliefs about the existence of life elsewhere have a large effect on any probabilistic conclusions we make about life elsewhere. As the authors say in the paper, “Life arose on Earth sometime in the first few hundred million years after the young planet had cooled to the point that it could support water-based organisms on its surface. The early emergence of life on Earth has been taken as evidence that the probability of abiogenesis is high, if starting from young-Earth-like conditions.”

A key part of all this is that life may have had a head start on Earth. Since then, it’s taken about 3.5 billion years for creatures to evolve to the point where they can think about such things. So this is where we find ourselves; looking out into the Universe and searching and wondering. But it’s possible that life may take a lot longer to get going on other worlds. We just don’t know, but many of the guesses have assumed that abiogenesis on Earth is standard for other planets.

What it all boils down to, is that we only have one data point, which is life on Earth. And from that point, we have extrapolated outward, concluding hopefully that life is plentiful, and we will eventually find it. We’re certainly getting better at finding locations that should be suitable for life to arise.

What’s maddening about it all is that we just don’t know. We keep looking and searching, and developing technology to find habitable planets and identify bio-markers for life, but until we actually find life elsewhere, we still only have one data point: Earth. But Earth might be exceptional.

As Spiegel and Turner say in the conclusion of their paper, ” In short, if we should find evidence of life that arose wholly idependently of us – either via astronomical searches that reveal life on another planet or via geological and biological studies that find evidence of life on Earth with a different origin from us – we would have considerably stronger grounds to conclude that life is probably common in our galaxy.”

With our growing understanding of Mars, and with missions like the James Webb Space Telescope, we may one day soon have one more data point with which we can refine our probabilistic understanding of other life in the Universe.

Or, there could be a sadder outcome. Maybe life on Earth will perish before we ever find another living microbe on any other world.

April 22, 2016May 5, 2016 by Evan Gough

Chinese Space Baby Research Lands In Mongolia

The return capsule from the Chinese SJ-10 mission landed in Mongolia on Monday April 18th. Image: Xinhua.

We’ve solved many of the problems associated with space travel. Humans can spend months in the zero-gravity of space, they can perform zero-gravity space-walks and repair spacecraft, they can walk on the surface of the Moon, and they can even manage, ahem, personal hygiene in space. We’re even making progress in understanding how to grow food in space. But one thing remains uncertain: can we make baby humans in space?

According to a recent successful Chinese experiment, the answer is a tentative yes. Sort of.

The Chinese performed a 96-hour experiment to test the viability of mammal embryos in space. They placed 6,000 mouse embryos in a micro-wave sized chamber aboard a satellite, to see if they would develop into blastocysts. The development of embryos into blastocysts is a crucial step in reproduction. Once the blastocysts have developed, they attach themselves to the wall of the uterus. Cameras on the inside of the chamber allowed Chinese scientists on Earth to monitor the experiment.

Duan Enkui, from the Chinese Academy of Sciences, who is the principal researcher for this experiment, told China Daily “The human race may still have a long way to go before we can colonise space, but before that we have to figure out whether it is possible for us to survive and reproduce in the outer space environment like we do on Earth.”

The Chinese say some of the embryos became blastocysts, and are claiming success in an endeavour that others have tried and failed at. NASA has performed similar experiments on Earth, where the micro-gravity conditions in space were duplicated. A study from 2009 showed that fertilization occurred normally in micro-gravity environments, but the eventual birth rate for the micro-gravity subjects was lower than for a 1G control group. The results from this study concluded that normal Earth gravity might be necessary for the blastocysts to successfully attach themselves to the uterus.

It’s important to note that at this point that China has proclaimed success by saying “some” of the embryos developed. But how many? There were 6,000 of them. Until they attach numbers to their claim, the word “some” doesn’t tell us much in terms of humans colonizing space. It also doesn’t tell us whether or not the crucial blastocyst to uterus attachment is inhibited by micro-gravity. Call us pedantic here at Universe Today, but it’s kind of important to know the numbers.

On the other hand, an increase in scientific curiosity related to procreating in space is a healthy development. The ideas and plans for missions to Mars and an eventual long-term presence in space are heating up. Making babies in space might not that relevant right now, but issues have a way of sneaking up on us.

The full results of this Chinese experiment will be interesting, if and when they’re made public. They may help clarify one aspect of the whole “making babies in space” problem. But in the bigger picture, things are still a little cloudy.

On shuttle mission STS-80, 2-cell mouse embryos were taken into space micro-gravity for 4 days. None of them developed into blastocysts, while a control group on the ground did. Another experiment in 1979, aboard Cosmos 1129, had male and female rats aboard. Though post-experiment results showed that some of the female rats had indeed ovulated, none of them gave birth. Two of the females even got pregnant, but the fetuses were reportedly r-absorbed.

Still, we have to give credit where its due. And the Chinese study has shown that mammal blastocysts can develop from embryos in micro-gravity. Still, there’s more to the space environment than low gravity. The radiation environment is much different. One study called the Space Pup study, led by principal investigator Teruhiko Wakayama, from the Riken Center for Developmental Biology, Japan, hopes to shed some light on that aspect of reproduction in space.

Space Pup will take sample of freeze-dried mouse sperm to the ISS for periods of 1, 12, and 24 months. Then, the samples will be returned to Earth and be used to fertilize mouse eggs.

There’s a lot more to learn in the area of reproduction in space. The next steps will involve keeping live mammals in space to monitor their reproduction. It’s not like ISS astronauts need more work to do, but maybe they’ll like having some animals along for company.

Maybe we’ll need to think outside the box when it comes to procreation in space. Maybe some type of in-vitro procedure will help humans spread the love in space. Or maybe, we’ll need to look to science fiction for inspiration. After all, countless alien species seem to be able to reproduce effectively, given the right circumstances.

This image needs no caption. But just in case, this is a still from the 1979 movie Alien. Image: 20th Century Fox.

April 22, 2016May 5, 2016 by Evan Gough

Dawn Just Wants To Make All The Other Probes Look Bad

An artist's illustration of NASA's Dawn spacecraft approaching Ceres. Image: NASA/JPL-Caltech. — An artist's illustration of NASA's Dawn spacecraft with its ion propulsion system approaching Ceres. Image: NASA/JPL-Caltech.

The Dawn spacecraft, NASA’s asteroid hopping probe, may not be going gently into that good night as planned. Dawn has visited Vesta and Ceres, and for now remains in orbit around Ceres. The Dawn mission was supposed to end after its rendezvous with Ceres, but now, reports say that the Dawn team has asked NASA to extend the mission to visit a third asteroid.

Dawn was launched in 2007, and in 2011 and 2012 spent 14 months at Vesta. After Vesta, it reached Ceres in March 2015, and is still in orbit there. The mission was supposed to end, but according to a report at New Scientist, the team would like to extend that mission.

Dawn is still is fully operational, and still has some xenon propellant remaining for its ion drive, so why not see what else can be achieved? There’s only a small amount of propellant left, so there’s only a limited selection of possible destinations for Dawn at this point. A journey to a far-flung destination is out of the question.

Chris Russell, of the University of California, Los Angeles, is the principal investigator for the Dawn mission. He told New Scientist, “As long as the mission extension has not been approved by NASA, I’m not going to tell you which asteroid we plan to visit,” he says. “I hope a decision won’t take months.”

If the Dawn mission is not extended, then its end won’t be very fitting for a mission that has accomplished so much. It will share the fate of some other spacecraft at the end of their lives; forever parked in a harmless orbit in an out of the way place, forgotten and left to its fate. The only other option is to crash it into a planet or other body to destroy it, like the Messenger spacecraft was crashed into Mercury at the end of its mission.

The crash and burn option isn’t available to Dawn though. The spacecraft hasn’t been sterilized. If it hasn’t been sterilized of all possible Earthly microbial life, then it is strictly forbidden to crash it into Ceres, or another body like it. Planetary protection rules are in place to avoid the possible contamination of other worlds with Earthly microbial life. It’s not likely that any microbes that may have hitched a ride aboard Dawn would have survived Dawn’s journey so far, nor is it likely that they would survive on the surface of Ceres, but rules are rules.

The secret of Dawn’s long-life and success is not only due to the excellent work by the teams responsible for the mission, it’s also due to Dawn’s ion-drive propulsion system. Ion drives, long dreamed of in science and science fiction, are making longer voyages into deep space possible.

Ion drives start very slow, but gain speed incrementally, continuing to generate thrust over long distances and long periods of time. They do all this with minimal propellant, and are ideal for long space voyages like Dawn’s.

The success of the Dawn mission is key to NASA’s plans for further deep space exploration. NASA continues to work on improving ion drives, and their latest project is the Advanced Electric Propulsion System (AEPS.) This project is meant to further develop the Hall Thruster, a type of ion-drive that NASA hopes will extend spacecraft mission capabilities, allow longer and deeper space exploration, and benefit commercial space activities as well.

The AEPS has the potential to double the thrust of current ion-drives like the one on Dawn. It’s a key component of NASA’s Journey to Mars. NASA also has plans for a robotic asteroid capture mission called Asteroid Redirect Mission, which will use the AEPS. That mission will visit an asteroid, retrieve a boulder- sized asteroid from the surface, and place it in orbit around the Moon. Eventually, astronauts will visit it and return samples to Earth for study. Very ambitious.

As far as the Dawn mission goes, it’s unclear what its next destination might be. Vesta and Ceres were chosen because they are thought be surviving protoplanets, formed at the same time as the other planets. But they stopped growing, and they remain largely undisturbed, so in that sense they are kind of locked in time, and are intriguing objects of study. There are other objects in the vicinity, but it would be pure guesswork to name any.

We are prone to looking at the past nostalgically, and thinking of prior decades as the golden age of space exploration. But as Dawn, and dozens of other current missions and scientific endeavours in space show us, we may well be in a golden age right now.

April 20, 2016 by Evan Gough

An Earth-like Planet Only 16 Light Years Away?

An artistic representation of Gliese 832 c against a stellar nebula background. A new paper says Gliese 832 might be home to another planet similar to this, but in the habitable zone. Credit: Planetary Habitability Laboratory at the University of Puerto Rico, Arecibo, NASA/Hubble, Stellarium.

Earth may have a new neighbour, in the form of an Earth-like planet in a solar system only 16 light years away. The planet orbits a star named Gliese 832, and that solar system already hosts two other known exoplanets: Gliese 832B and Gliese 832C. The findings were reported in a new paper by Suman Satyal at the University of Texas, and colleagues J. Gri?th, and Z. E. Musielak.

Gliese 832B is a gas giant similar to Jupiter, at 0.64 the mass of Jupiter, and it orbits its star at 3.5 AU. G832B probably plays a role similar to Jupiter in our Solar System, by setting gravitational equilibrium. Gliese 832C is a Super-Earth about 5 times as massive as Earth, and it orbits the star at a very close 0.16 AU. G832C is a rocky planet on the inner edge of the habitable zone, but is likely too close to its star for habitability. Gliese 832, the star at the center of it all, is a red dwarf about half the size of our Sun, in both mass and radius.

The newly discovered planet is still hypothetical at this point, and the researchers put its mass at between 1 and 15 Earth masses, and its orbit at between 0.25 to 2.0 AU from Gliese 582, its host star.

The two previously discovered planets in Gliese 832 were discovered using the radial velocity technique. Radial velocity detects planets by looking for wobbles in the host star, as it responds to the gravitational tug exerted on it by planets in orbit. These wobbles are observable through the Doppler effect, as the light of the affected star is red-shifted and blue-shifted as it moves.

The team behind this study re-analyzed the data from the Gliese 832 system, based on the idea that the vast distance between the two already-detected planets would be home to another planet. According to other solar systems studied by Kepler, it would be highly unusual for such a gap to exist.

As they say in their paper, the main thrust of the study is to explore the gravitational effect that the large outer planet has on the smaller inner planet, and also on the hypothetical Super-Earth that may inhabit the system. The team conducted numerical simulations and created models constrained by what’s known about the Gliese 832 system to conclude that an Earth-like planet may orbit Gliese 832.

This can all sound like some hocus-pocus in a way, as my non-science-minded friends like to point out. Just punch in some numbers until it shows an Earth-like planet, then publish and get attention. But it’s not. This kind of modelling and simulation is very rigorous.

Putting in all the data that’s known about the Gliese 832 system, including radial velocity data, orbital inclinations, and gravitational relationships between the planets and the star, and between the planets themselves, yields bands of probability where previously undetected planets might exist. This result tells planet hunters where to start looking for planets.

In the case of this paper, the result indicates that “there is a slim window of about 0.03 AU where an Earth-like planet could be stable as well as remain in the HZ.” The authors are quick to point out that the existence of this planet is not proven, only possible.

The other planets were found using the radial velocity method, which is pretty reliable. But radial velocity only provides clues to the existence of planets, it doesn’t prove that they’re there. Yet. The authors acknowledge that a larger number of radial velocity observations are needed to confirm the existence of this new planet. Barring that, either the transit method employed by the Kepler spacecraft, or direct observation with powerful telescopes, may also provide positive proof.

So far, the Kepler spacecraft has confirmed the existence of 1,041 planets. But Kepler can’t look everywhere for planets. Studies like these are crucial in giving Kepler starting points in its search for exoplanets. If an exoplanet can be confirmed in the Gliese 832 system, then it also confirms the accuracy of the simulation that the team behind this paper performed.

If confirmed, G832 C would join a growing list of exoplanets. It wasn’t long ago that we knew almost nothing about other solar systems. We only had knowledge of our own. And even though it was always unlikely that our Solar System would for some reason be special, we had no certain knowledge of the population of exoplanets in other solar systems.

Studies like this one point to our growing understanding of the dynamics of other solar systems, and the population of exoplanets in the Milky Way, and most likely throughout the cosmos.

April 20, 2016May 5, 2016 by Evan Gough

Our Sun May Have Eaten A Super Earth For Breakfast

A new paper says that a Super-Earth may have formed in our Solar System and been swallowed by the Sun. Image Credit: ESA/Hubble, M. Kornmesser

Our Solar System sure seems like an orderly place. The orbits of the planets are predictable enough that we can send spacecraft on multi-year journeys to them and they will reliably reach their destinations. But we’ve only been looking at the Solar System for the blink of an eye, cosmically speaking.

The young Solar System was a much different place. Things were much more chaotic before the planets settled into the orbital stability that they now enjoy. There were crashings and smashings aplenty in the early days, as in the case of Theia, the planet that crashed into Earth, creating the Moon.

Now, a new paper from Rebecca G. Martin and Mario Livio at the University of Nevada, Las Vegas, says that our Solar System may have once had an additional planet that perished when it plunged into the Sun. Strangely enough, the evidence for the formation and existence of this planet may be the lack of evidence itself. The planet, which may have been what’s called a Super-Earth, would have formed quite close to the Sun, and then been destroyed when it was drawn into the Sun by gravity.

In the early days of our Solar System, the Sun would have formed in the centre of a mass of gas and dust. Eventually, when it gained enough mass, it came to life in a burst of atomic fusion. Surrounding the Sun was a protoplanetary disk of gas and dust, out of which the planets formed.

What’s missing in our Solar System is any bodies, or even rocky debris in the zone between Mercury and the Sun. This may seem normal, but the Kepler mission tells us it’s not. In over half of the other solar systems it’s looked at, Kepler has found planets in the same zone where our Solar System has none.

A key part of this idea is that planets don’t always form in situ. That is, they don’t always form at the place where they eventually reach orbital stability. Depending on a number of factors, planets can migrate inward towards their star or outwards away from their star.

Martin and Livio, the authors of the study, think that our Solar System did form a Super-Earth, and rather than it migrating outward, it fell into the Sun. According to them, the Super-Earth most probably formed in the inner regions of our Solar System, on the inside of Mercury’s orbit. The fact that there are no objects there, and no debris of any kind, suggests that the Super-Earth formed close to the Sun, and that its formation cleared that area of any debris. Then, once formed, it fell into the Sun, removing all evidence of its existence.

The authors also note another possible cause for the Super-Earth to have fallen into the Sun. They propose that Jupiter may have migrated inward to about 1.5 AUs from the Sun. At that point, it got locked into resonance with Saturn. Then, both gas giants migrated outward to their current orbits. This process would have shepherded a Super-Earth into the Sun, destroying it.

Some of the thinking behind this whole theory involves the size of the inner terrestrial planets in our Solar System. They’re very small in comparison to other systems studied by the Kepler Mission. If a Super-Earth had formed in the inner part of our System, it would have dominated the accretion of available material, leaving Mercury, Venus, Earth and Mars starved for matter.

A key idea behind this study is what’s known as a dead zone. In terms of a solar system and a protoplanetary disk, a dead zone is a zone of low turbulence which favors the formation of planets. A system with a dead zone would have enough material to allow Super-Earths to form in-situ, and they would not have to migrate inward from further out in the system. However, since large planets like Super-Earths take a long time to fully form, this dead zone would have to be long-lived.

If a protoplanetary disk lacks a dead zone, it is likely too turbulent for the formation of a Super-Earth close to the star. A turbulent protoplanetary disk favors the formation of Super-Earths further out, which would then migrate inwards towards the star. Also, a turbulent disk allows for quicker migration of planets, while a pronounced dead zone inhibits migration.

As the authors say in the conclusion of their study, “The lack of Super–Earths in our solar system is somewhat puzzling given that more than half of observed exoplanetary systems contain one. However, the fact that there is nothing
inside of Mercury’s orbit may not be a coincidence.” They go on to conclude that in our Solar System, the likely scenario is the in situ formation of a Super-Earth which subsequently fell into the Sun.

There are a lot of variables that have to be fine-tuned for this scenario to happen. The young solar system would need a dead zone, the depth of the turbulence in the protoplanetary disk would have to be just right, and the disk would have to be the right temperature. The fact that these things have to be within a certain range may explain why we don’t have a Super-Earth in our system, while over half of the systems studied by Kepler do have one.

April 19, 2016May 5, 2016 by Evan Gough

Gravity Waves On Pluto?

The varying brightness in Pluto's atmosphere is caused by atmospheric gravity waves, or buoyancy waves. Image: NASA/New Horizons/Johns Hopkins APL/SWRI

New Horizons’ historic journey to Pluto and beyond continues to provide surprises. As data from the spacecraft’s close encounter with Pluto and its moons arrives at Earth, scientists are piecing together an increasingly intriguing picture of the dwarf planet. The latest discovery is centred around Pluto’s atmosphere, and what are called ‘atmospheric gravity waves.’

Atmospheric gravity waves are a different phenomenon than the gravity waves that were detected for the first time in February, 2016. Those gravity waves are ripples in the fabric of space time, first predicted by Albert Einstein back in 1916. After years of searching, the LIGO instrument detected gravity waves that resulted from two black holes colliding. The discovery of what you might call ‘Einsteinian Gravity Waves’ may end up revolutionizing astronomy.

New Horizons has revealed surprise after surprise in its study of Pluto. Its atmosphere has turned out to be much more complex than anybody expected. It’s composed of 90% nitrogen, with extensive haze layers. Scientists have discovered that Pluto’s atmosphere can vary in brightness depending on viewpoint and illumination, while the vertical structure of the layered haze remains unchanged.

Scientists studying the New Horizons’ data think that atmospheric gravity waves, also called buoyancy waves, are responsible. Atmospheric gravity waves are known to exist on only two other planets; Earth and Mars. They are typically caused by wind flowing over obstructions like mountain ranges.

The layers in Pluto’s atmosphere, and their varying brightness, are most easily seen when they are backlit by the Sun. This was the viewpoint New Horizons had when it captured these images on its departure from Pluto on July 14, 2015. The spacecraft’s Long Range Reconnaissance Imager (LORRI) captured them, using time intervals of 2 to 5 hours. What they show is the brightness of the layers changing by 30% without any change in their height above the surface of the planet.

LORRI, as its name suggests, is a long range image capture instrument. It also captures high resolution geologic data, and was used to map Pluto’s far side. The principal investigator for LORRI is Andy Cheng, from the Applied Physics Laboratory at Johns Hopkins University, in Maryland. “Pluto is simply amazing,” said Andy Cheng. “When I first saw these images and the haze structures that they reveal, I knew we had a new clue to the nature of Pluto’s hazes. The fact that we don’t see the haze layers moving up or down will be important to future modelling efforts.”

Overall, Pluto and its system of moons has turned out to be a much more dynamic place than previously thought. A geologically active landscape, possible ice volcanoes, eroding cliffs made of methane ice, and more, have woken us up to Pluto’s complexity. But its atmosphere has turned out to be just as complex and puzzling.

New Horizons has departed the Pluto system now, and is headed for the Kuiper Belt. The Kuiper Belt is considered a relic of the early Solar System. New Horizons will visit another icy world there, and hopefully continue on to the edge of the heliosphere, the same way the Voyage probes have. New Horizons has enough energy to last until approximately the mid-2030’s, if all goes well.

April 18, 2016May 5, 2016 by Evan Gough

Antarctica Provides Plenty Of Mars Samples Right Now

Mars! Martian meteorites make their way to Earth after being ejected from Mars by a meteor impact on the Red Planet. Image: NASA/National Space Science Data Center.

Sometimes, the best way to study Mars is to stay home. There’s no substitute for actual missions to Mars, but pieces of Mars have made the journey to Earth, and saved us the trip. Case in point: the treasure trove of Martian meteorites that NASA is gathering from Antarctica.

NASA scientists aren’t the first ones to find meteorites in the Earth’s polar regions. As early as the 9th century, people in the northern polar regions made use of iron from meteorites for tools and hunting weapons. The meteorite iron was traded from group to group over long distances. But for NASA, the hunt for meteorites is focused on Antarctica.

In Antarctica, the frigid temperatures preserve meteorites for a long time, which makes them valuable artifacts in the quest to understand Mars. Meteorites tend to accumulate in places where creeping glacial ice moves them to. When the ice meets a rock obstacle, the meteorites are deposited there, making them easier to find. Recently arrived meteorites are also easily spotted on the surface of the Antarctica ice.

The US began collecting meteorites in Antarctica in 1976, and to date more than 21,000 meteorites and meteorite fragments have been found. In fact, more of them are found in Antarctica than in the rest of the world combined. These meteorites are then shared with scientists around the world.

Collecting meteorites in Antarctica is not a walk in the park. It’s physically gruelling and hazardous work. Antarctica is not an easy environment to live and work in, and just surviving there takes planning and teamwork. But the scientific payoff is huge, which keeps NASA going back.

Meteorites from the Moon and other bodies also arrive on Earth, and are collected in Antarctica. They can tell scientists important things about the evolution and formation of the Solar System, the origin of organic chemical compounds necessary for life, and the origin of the planets themselves.

How Do Martian Meteorites Get To Earth?

A few things have to go right for a Martian meteorite to make it to Earth. First, a meteorite has to collide with Mars. That meteorite has to be big enough, and hit the surface of Mars with enough force, that rock from Mars is propelled off the surface with enough speed to escape Mars’ gravity.

After that, the meteor has to travel through space and avoid a thousand other fates, like being drawn to one of the other planets, or the Sun, by the gravitational pull of those bodies. Or being flung off into the far reaches of empty space, lost forever. Then, if it manages to make it to Earth, and be pulled in by Earthly gravity, it must be large enough to survive entry into Earth’s atmosphere.

The Science

Part of the scientific value in meteorites lies not in their source, but in the time that they were formed. Some meteorites have travelled through space for so long, they’re like time travellers. These ancient meteorites can tell scientists a lot about conditions in the early Solar System.

This is the Hoba meteorite from Namibia. It is the largest known intact meteorite, at 60 tonnes. Image: Patrick Giraud, http://creativecommons.org/licenses/by/2.5 — This the Hoba meteorite from Namibia. At 60 tonnes, it is the largest known intact meteorite. Image: Patrick Giraud, http://creativecommons.org/licenses/by/2.5

Meteorites from Mars tell scientists a few things. Since they’ve survived re-entry into Earth’s atmosphere, they can tell engineers about the dynamics of such a journey, and help inform spacecraft design. Since they contain chemical signatures and elements unique to Mars, they can also tell mission specialists things about surviving on Mars.

They can also provide clues to one of the greatest mysteries in space exploration: Did life exist on Mars? A Martian meteorite found in the Sahara desert in 2011 contained ten times the amount of water as other Martian meteorites, and added evidence to the idea that Mars was once a wet world, suitable for life.

NASA’s program to hunt for meteorites in Antarctica has been going strong for many years, and there’s really no reason to stop doing it, since this is the only way to get Martian samples into a laboratory. Each one they find is like a puzzle piece, and like a jigsaw puzzle, you never know which one will complete the big picture.

April 18, 2016April 8, 2018 by Evan Gough

Dwarf Dark Matter Galaxy Hides In Einstein Ring

The large blue light is a lensing galaxy in the foreground, called SDP81, and the red arcs are the distorted image of a more distant galaxy. By analyzing small distortions in the red, distant galaxy, astronomers have determined that a dwarf dark galaxy, represented by the white dot in the lower left, is companion to SDP81. The image is a composite from ALMA and the Hubble. Image: Y. Hezaveh, Stanford Univ./ALMA (NRAO/ESO/NAOJ)/NASA/ESA Hubble Space Telescope — The large blue light is a lensing galaxy in the foreground, called SDP81, about 4 billion light years away. The red arcs are the distorted image of a more distant galaxy, about 12 billion light years away. By analyzing small distortions in the red, distant galaxy, astronomers have determined that a dwarf dark galaxy, represented by the white dot in the lower left, is bound to SDP81. The image is a composite from ALMA and the Hubble. Image: Y. Hezaveh, Stanford Univ./ALMA (NRAO/ESO/NAOJ)/NASA/ESA Hubble Space Telescope

Everybody knows that galaxies are enormous collections of stars. A single galaxy can contain hundreds of billions of them. But there is a type of galaxy that has no stars. That’s right: zero stars.

These galaxies are called Dark Galaxies, or Dark Matter Galaxies. And rather than consisting of stars, they consist mostly of Dark Matter. Theory predicts that there should be many of these Dwarf Dark Galaxies in the halo around ‘regular’ galaxies, but finding them has been difficult.

Now, in a new paper to be published in the Astrophysical Journal, Yashar Hezaveh at Stanford University in California, and his team of colleagues, announce the discovery of one such object. The team used enhanced capabilities of the Atacamas Large Millimeter Array to examine an Einstein ring, so named because Einstein’s Theory of General Relativity predicted the phenomenon long before one was observed.

An Einstein Ring is when the massive gravity of a close object distorts the light from a much more distant object. They operate much like the lens in a telescope, or even a pair of eye-glasses. The mass of the glass in the lens directs incoming light in such a way that distant objects are enlarged.

Einstein Rings and gravitational lensing allow astronomers to study extremely distant objects, by looking at them through a lens of gravity. But they also allow astronomers to learn more about the galaxy that is acting as the lens, which is what happened in this case.

If a glass lens had tiny water spots on it, those spots would add a tiny amount of distortion to the image. That’s what happened in this case, except rather than microscopic water drops on a lens, the distortions were caused by tiny Dwarf Galaxies consisting of Dark Matter. “We can find these invisible objects in the same way that you can see rain droplets on a window. You know they are there because they distort the image of the background objects,” explained Hezaveh. The difference is that water distorts light by refraction, whereas matter distorts light by gravity.

As the ALMA facility increased its resolution, astronomers studied different astronomical objects to test its capabilities. One of these objects was SDP81, the gravitational lens in the above image. As they examined the more distant galaxy being lensed by SDP81, they discovered smaller distortions in the ring of the distant galaxy. Hezaveh and his team conclude that these distortions signal the presence of a Dwarf Dark Galaxy.

But why does this all matter? Because there is a problem in the Universe, or at least in our understanding of it; a problem of missing mass.

Our understanding of the formation of the structure of the Universe is pretty solid, at least in the larger scale. Predictions based on this model agree with observations of the Cosmic Microwave Background (CMB) and galaxy clustering. But our understanding breaks down somewhat when it comes to the smaller scale structure of the Universe.

One example of our lack of understanding in this area is what’s known as the Missing Satellite Problem. Theory predicts that there should be a large population of what are called sub-halo objects in the halo of dark matter surrounding galaxies. These objects can range from things as large as the Magellanic Clouds down to much smaller objects. In observations of the Local Group, there is a pronounced deficit of these objects, to the tune of a factor of 10, when compared to theoretical predictions.

Because we haven’t found them, one of two things needs to happen: either we get better at finding them, or we modify our theory. But it seems a little too soon to modify our theories of the structure of the Universe because we haven’t found something that, by its very nature, is hard to find. That’s why this announcement is so important.

The observation and identification of one of these Dwarf Dark Galaxies should open the door to more. Once more are found, we can start to build a model of their population and distribution. So if in the future more of these Dwarf Dark Galaxies are found, it will gradually confirm our over-arching understanding of the formation and structure of the Universe. And it’ll mean we’re on the right track when it comes to understanding Dark Matter’s role in the Universe. If we can’t find them, and the one bound to the halo of SDP81 turns out to be an anomaly, then it’s back to the drawing board, theoretically.

It took a lot of horsepower to detect the Dwarf Dark Galaxy bound to SDP81. Einstein Rings like SDP81 have to have enormous mass in order to exert a gravitational lensing effect, while Dwarf Dark Galaxies are tiny in comparison. It’s a classic ‘needle in a haystack’ problem, and Hezaveh and his team needed massive computing power to analyze the data from ALMA.

ALMA will consist of 66 individual antennae like these when it is complete. The facility is located in the Atacama Desert in Chile, at 5,000 meters above sea level. Credit: ALMA (ESO / NAOJ / NRAO)

ALMA, and the methodology developed by Hezaveh and team will hopefully shed more light on Dwarf Dark Galaxies in the future. The team thinks that ALMA has great potential to discover more of these halo objects, which should in turn improve our understanding of the structure of the Universe. As they say in the conclusion of their paper, “… ALMA observations have the potential to significantly advance our understanding of the abundance of dark matter substructure.”