Astronomers have catalogued just 20 or so of these brief, superbright flashes, which are known as fast radio bursts (FRBs), since the first one was detected in 2007. FRBs seem to be coming from galaxies billions of light-years away, but what’s causing them remains a mystery.
“Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence,” study co-author Avi Loeb, a theorist at the Harvard-Smithsonian Center for Astrophysics, said in a statement Thursday (March 9). “An artificial origin is worth contemplating and checking.” ]
One potential artificial origin, according to the new study, might be a gigantic radio transmitter built by intelligent aliens. So Loeb and lead author Manasvi Lingam, of Harvard University, investigated the feasibility of this possible explanation.
And the huge amounts of energy involved wouldn’t necessarily melt the structure, as long as it was water-cooled. So, Lingam and Loeb determined, such a gigantic transmitter is technologically feasible (though beyond humanity’s current capabilities).
Why would aliens build such a structure? The most plausible explanation, according to the study team, is to blast interstellar spacecraft to incredible speeds. These craft would be equipped with light sails, which harness the momentum imparted by photons, much as regular ships’ sails harness the wind. (Humanity has demonstrated light sails in space, and the technology is the backbone of Breakthrough Starshot, a project that aims to send tiny robotic probes to nearby star systems.)
Indeed, a transmitter capable of generating FRB-like signals could drive an interstellar spacecraft weighing 1 million tons or so, Lingam and Loeb calculated.
“That’s big enough to carry living passengers across interstellar or even intergalactic distances,” Lingam said in the same statement.
Humanity would catch only fleeting glimpses of the “leakage” from these powerful beams (which would be trained on the spacecraft’s sail at all times), because the light source would be moving constantly with respect to Earth, the researchers pointed out.
The duo took things a bit further. Assuming that ET is responsible for most FRBs, and taking into account the estimated number of potentially habitable planets in the Milky Way (about 10 billion), Lingam and Loeb calculated an upper limit for the number of advanced alien civilizations in a galaxy like our own: 10,000.
Lingam and Loeb acknowledge the speculative nature of the study. They aren’t claiming that FRBs are indeed caused byaliens; rather, they’re saying that this hypothesis is worthy of consideration.
“Science isn’t a matter of belief; it’s a matter of evidence,” Loeb said. “Deciding what’s likely ahead of time limits the possibilities. It’s worth putting ideas out there and letting the data be the judge.”
The new study has been accepted for publication in The Astrophysical Journal Letters. You can read it for free on the online preprint site arXiv.org.
Scientists, have at it: NASA has released raw data from the Kepler Space Telescope probing the many Earth-size planets around the star TRAPPIST-1.
In February, data from the Spitzer Space Telescope revealed that seven planets orbit the ultracool dwarf star, and now, the recently released Kepler data (and its final, processed version) will give a complementary look at the worlds, three of which might orbit in the star’s habitable zone.
Kepler’s observations could provide more detail about the gravitational interactions among the planets, and perhaps reveal even more planets around the star, NASA officials said in a statement
As part of its K2 mission, Kepler examined the TRAPPIST-1 system from Dec. 15, 2016, to March 4, 2017 — and its data became much more exciting upon the Feb. 22 announcement of additional Earth-size planets orbiting the star. Yesterday (March 8), Kepler researchers released the unprocessed data from that survey for astronomers to use in preparing research proposals.
“Scientists and enthusiasts around the world are invested in learning everything they can about these Earth-size worlds,” Geert Barentsen, K2 research scientist at NASA’s Ames Research Center in California, said in the NASA statement. “Providing the K2 raw data as quickly as possible was a priority to give investigators an early look so they could best define their follow-up research plans. We’re thrilled that this will also allow the public to witness the process of discovery.”
The release is timely because many proposals to study TRAPPIST-1 this winter with ground-based telescopes are due this month, the statement said.
On the Kepler website, Barentsen encouraged scientists to dig into the results and blog or tweet analysis, but advised everyone to wait until the final, processed results are released in late May to cite them in journal papers.
Barentsen also included a preliminary graph of the light curve, the way the star darkened as planets passed across it, which shows hints of at least six planets (as well as star spots) visible in the data.
When K2’s December-March observation plan was established, TRAPPIST-1’s planets were unknown, and the star system wasn’t on the list for investigation. But researchers found evidence of three planets around the star in May 2016, so the Kepler team adjusted the mission to include the newly exciting target.
“We were lucky that the K2 mission was able to observe TRAPPIST-1,” Michael Haas, science office director for the Kepler and K2 missions at Ames, said in the statement. “The observing field for Campaign 12 [the December-March campaign] was set when the discovery of the first planets orbiting TRAPPIST-1 was announced, and the science community had already submitted proposals for specific targets of interest in that field.
“The unexpected opportunity to further study the TRAPPIST-1 system was quickly recognized, and the agility of the K2 team and science community prevailed once again,” Haas added.
Kepler’s original and K2 missions have been responsible for more than 2,400 confirmed exoplanet discoveries. The space telescope uses extremely precise measurements of stars’ brightness over time to identify little dips in brightness that indicate planets in front of the star, called the transit method of exoplanet detection.
Although the transit method can identify only planets that are oriented to pass by the star from Earth’s point of view, it’s an extremely powerful technique. The Spitzer Space Telescope, which counted the seven planets around TRAPPIST-1, used a similar process measuring infrared light.
NASA’s upcoming James Webb Space Telescope, another infrared telescope, could give researchers an even more detailed view of the planets, and help scientists measure whether those potentially habitable ones have atmospheres friendly to life. The telescope will be powerful enough to analyze the light passing from the star through the planets’ atmospheres, letting researchers determine their composition.
Pluto’s “demotion” to a dwarf planet back in 2006 is still a touchy subject, even among scientists.
When you account for the fact that astronomers, who study stars and black holes, were the ones who decided on the definition of a planet that resulted in Pluto’s declassification, it’s understandable that various planetary scientists don’t even want to talk about it.
“It’s often like bringing up politics and religion in polite conversation,” said planetary geologist Kirby Runyon from Johns Hopkins University, in an email to Seeker. “Some planetary scientists can’t understand why some of us care so much. Generally, it’s not discussed over a beer at a conference.”
But Runyon does care. In fact, he’s so passionate about what constitutes a planet, that he is the lead author of a new paper that proposes a new geophysical-based definition. This revised description is centered on intrinsic physical properties such as surface features instead of the extrinsic orbital characteristics that the International Astronomical Union (IAU) used as the basis of much of their planetary definition when they formulated it nearly 11 years ago.
Runyon and his co-authors — including Alan Stern, the principal investigator of the New Horizons mission to Pluto — will present their paper at the 48th Lunar and Planetary Science Conference in March.
The new paper states the definition of a planet as “a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters.”
In other words: Anything round in space that isn’t a star.
While this definition is refreshingly simple — particularly compared to confusing requirements about clearing orbital zones — Runyon and his co-authors say that this definition is “in keeping with both sound scientific classification and peoples’ intuition.”
But their proposed definition would increase the number of ‘planets’ in our solar system to over 110, including Earth’s Moon and about 18 other moons, a few asteroids, and numerous Kuiper Belt Objects.
How would students memorize all of those planets?
They wouldn’t, answer Runyon and his colleagues. Instead, they should focus on the organization system of the solar system.
“Understanding the natural organization of the Solar System is much more informative than rote memorization,” says the paper. “Teaching the zones of the Solar System from the Sun outward and the types of planets and small bodies in each is perhaps the best approach.”
There are many who feel that the revised planet definition adopted by the IAU is technically flawed, since it doesn’t address extrasolar planets or wandering ‘rogue’ planets — and, again, there’s the whole zone clearing requirement, which many experts say no planet in our solar system can satisfy.
When I spoke with Stern about this last year, he didn’t mince words.
“Astronomers aren’t experts in planetary science, and they basically passed a bunch of B.S. off on the public back in 2006 with a planet classification so flawed that it rules the Earth out as a planet, too,” he said. “A week later, hundreds of planetary scientists, more people than at the IAU vote, signed a petition that rejects the new definition. If you go to planetary science meetings and hear technical talks on Pluto, you will hear experts calling it a planet every day.”
“Planetary scientists call lots of round things planets, including Pluto and Titan,” he said. “If, in linguistics, definition is influenced by usage (especially by experts in the field), then by usage alone Pluto is a planet.”
Runyon also feels this new definition can and should be used without needing ratification by the IAU.
“We don’t need to give the IAU the authority to tell us what a planet is,” he remarked. “To be fair, the IAU serves a great purpose in astronomy and does great stuff, but they don’t need to tell planetary geologists what a planet is or isn’t.”
Runyon admitted that some planetary geologists are okay with the IAU definition, and others don’t really care. Some can’t understand why it’s a point of contention.
“For whatever reason, this is something that I care deeply about,” he said, “I think partly because I want the general public to support space exploration and how they view the solar system affects their interest level.”
That’s illustrated in the implicit assumption in the question Runyon said he gets often: Why did you send a spacecraft to Pluto if it’s not a planet anymore?
It’s as though “non-planets” cease to be interesting enough to warrant scientific exploration, the paper says, although this wasn’t the intention of the IAU.
Runyon said that he chose to submit this paper as a poster at the upcoming Lunar and Planetary Science Conference in the K-12 education section, because he wants teachers to teach this new definition, as he sees this as the most influential way to get the public to adopt it.
“Get ’em while they’re young!” he quipped.
The search for Martian life may take NASA’s next Red Planet rover to a site already explored by one of its smaller cousins.
Columbia Hills/Gusev Crater, which NASA’s now-dead Spirit rover studied intensively from 2004 through 2009, is one of three finalist landing sites for the agency’s next Mars rover, a life-hunting machine scheduled to launch in 2020.
Spirit found evidence of an ancient hydrothermal system, meaning Columbia Hills/Gusev once hosted liquid water and an energy source — two of the key ingredients necessary for life as we know it.
“Because NASA’s stated objective for the 2020 rover is to seek signs of past microbial life, the fact that we can point to possible signs of microbial life among rocks in the Columbia Hills is a major reason to go back,” said Steven Ruff, associate research professor at Arizona State University’s Mars Space Flight Facility in Tempe, Arizona.
NASA held a landing-site decision meeting in Monrovia, California, last month, from Feb. 8 through Feb. 10.
The meeting involved more than 250 scientists and spacecraft engineers, who took part in person or via the Internet. After the meeting ended, the participants spent several days debating options and voting. They finally settled on three potential landing sites for the 2020 rover. In addition to Columbia Hills/Gusev, the researchers selected:
Jezero Crater. A place that exhibits a dried-up lake and possibly a storehouse of past microbial For the most part, the 2020 rover will follow the landing playbook used by NASA’s Mars rover Curiosity, which touched down inside Gale Crater in August 2012 and is currently exploring the foothills of the 3.4-mile-high (5.5 kilometers) Mount Sharp.
The 2020 Mars rover will experience the same “7 minutes of terror” entry, descent and landing scenario, which ends with the use of a rocket-powered sky crane lowering the rover onto Mars terrain. [7 Minutes of Terror: Curiosity Rover’s Risky Mars Landing (Video)]
But the new rover features some updates that will make its landing special, said Allen Chen, entry, descent and landing lead for Mars 2020 at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Two new techniques — Range Trigger and Terrain-Relative Navigation —make it feasible to shrink the rover’s landing ellipse considerably, compared to previous Mars landers, Chen said. Those new abilities allow the rover to “get close to the fun stuff” that scientists are hungry for, Chen told Space.com.
Terrain-Relative Navigation will allow the 2020 rover to avoid rough terrain, sharp slopes and other perils, while Chen said that Range Trigger permits precise timing of parachute release. Onboard software will autodecide if the rover’s parachute is to be deployed early or late, given how close the robot might be to its desired touchdown target, Chen said..
Mars 2020 and Curiosity also have different mission goals. Curiosity is tasked primarily with determining whether or not Gale Crater has ever been capable of supporting microbial life — a question the rover answered in the affirmative early in its mission. But Mars 2020 will actually hunt for signs of past life.
The 2020 rover will drill and cache the most compelling astrobiological samples at the selected site for later pickup and return to Earth. Once transported back to our home world, specimens would be subject to the best scientific scrutiny that researchers can muster, given a bevy of powerful and innovative lab tools.
Just when — and how — these samples will make it to Earth is unknown; at present, there is no programmatic/budgetary go-ahead on a pickup mission.
It’s possible that astronauts could be involved; after all, NASA is also working to get people to the vicinity of the Red Planet sometime in the 2030s.
“I’ve thought for a couple of years now that sending humans to pick up the sample cache in orbit around Mars would be a great way to advance exploration goals,” Ruff said.
“I have joked that it would be like Apollo 8 going for takeout,” he added, referring to the nonlanding human mission that orbited the moon in December 1968.
“We’d be exercising the hardware needed to get humans to Mars and back and completing a major scientific objective of returning Martian samples to Earth,” Ruff said. “But if the development timeline for such a mission is substantially longer than a robotic sample-return mission, I’d have a different opinion.”
“I am not very enthusiastic about Mars 2020,” said Chris McKay, a research scientist at NASA’s Ames Research Center in Moffett Field, California. “It will sure be fun to have another big rover on Mars, but I don’t think it will advance the science much over Curiosity.”
McKay underscored two things gleaned from Curiosity — items that seem to have been ignored, he said.
“First, to search for signs of life, we have to collect samples. 2020’s approach to do all the in situ science with instruments that don’t require a sample is a step backward,” McKay told Space.com.
“The second lesson from Curiosity is that we need to get these samples from deep,” McKay said. At old equatorial sites on Mars, “deep” means many meters, he said. In the polar sites — like the Phoenix lander site that was robotically explored in 2008 — 20 inches (51 centimeters) may be enough, McKay added.
McKay said the Mars 2020 rover will collect samples only from very shallow depths.
“I doubt there will be much interest in going back to Mars to pick up these samples,” he said. “But certainly the coring and caching will be interesting technology demonstrations.”
Mars getting busy
The 2020 rover isn’t the only craft being prepped for a trip to Mars in the near future.
NASA aims to launch a lander called InSight next year, to investigate the Red Planet’s interior structure. The life-hunting ExoMars rover, a joint effort of the European Space Agency and Russia’s space agency, is scheduled to lift off in 2021, and China plans to launch its own Mars rover in that same general time frame.
And then there’s SpaceX. Elon Musk’s company intends to launch its uncrewed Dragon capsule toward Mars in 2020, with follow-up missions occurring every two years or so thereafter. Crewed missions aboard the company’s Interplanetary Transport System could begin sometime in the 2020s as well.
Advocates of Pluto’s planethood are about to fire another salvo in the decade-long debate about the famous object’s status.
Scientists on NASA’s New Horizons mission, which performed the first-ever flyby of Pluto in July 2015, will officially propose a new definition of “planet” next month, at the 48th Lunar and Planetary Science Conference in The Woodlands, Texas.
The new definition would replace, or supersede, the one devised by the International Astronomical Union (IAU) in 2006. A planet, the IAU determined, is a body that orbits the sun without being the moon of another object; is large enough that its own gravity has rounded it into a sphere (but not so large that it undergoes fusion reactions, like a star); and has “cleared its neighborhood” of most other bodies.
Pluto failed to meet this last criterion, because its neighborhood — the vast Kuiper Belt beyond Neptune’s orbit — is full of small, icy objects. So Pluto was stripped of the planethood it had enjoyed since its 1930 discovery, and was reclassified as a dwarf planet.
Many scientists and laypeople alike cried foul at the time, and have continued to object to the definition and Pluto’s concomitant “demotion.” The New Horizons team members, including mission principal investigator Alan Stern, lay out their main arguments against the IAU definition in the paper they will present next month:
“First, it recognizes as planets only those objects orbiting our sun, not those orbiting other stars or orbiting freely in the galaxy as ‘rogue planets,'” the researchers, led by K.D. Runyon of Johns Hopkins University in Baltimore, wrote in the paper, which you can read here. “Second, it requires zone clearing, which no planet in our solar system can satisfy since new small bodies are constantly injected into planet-crossing orbits, like NEOs [near-Earth objects] near Earth. Finally, and most severely, by requiring zone clearing, the mathematics of the definition are distance-dependent, requiring progressively larger objects in each successive zone. For example, even an Earth-sized object in the Kuiper Belt would not clear its zone.”
As an alternative, the researchers will propose a “geophysical definition” — one based solely on an object’s intrinsic characteristics (and not on how it interacts with its environment). Here it is:
“A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters.”
Or, more simply: “round objects in space that are smaller than stars.” (The tricky matter of brown dwarfs, “failed stars” that are larger than planets but smaller than true stars, is left up in the air, “so as to not force a premature definition on the larger end of planetary scales,” the researchers wrote.)
Pluto would regain its planethood under this new definition, and a lot of other bodies would be viewed as planets for the first time — including Earth’s moon (and any other moon large enough to be spherical, such as the Jovian satellite Europa). Indeed, the number of officially recognized planets would balloon from eight to about 110, the researchers wrote.
But that’s OK, they added; there’s no rule stating that schoolchildren must be able to memorize all the planets. And swelling the planet ranks would better convey the exciting diversity found throughout the solar system, the team members wrote.
“This definition highlights to the general public and policymakers the many fascinating worlds in our solar system that remain unexplored and are worthy of our exploration, along with the necessary budgets,” they wrote.
But not everyone is clamoring for Pluto to be reclassified. One person who’s quite happy with the status quo is Mike Brown, an astronomer at the California Institute of Technology in Pasadena. Brown and his team have discovered many objects in the outer solar system, showing that Pluto is far from the only large object in the Kuiper Belt.
This growing realization seems to have spurred the IAU to draft its 2006 definition; indeed, Brown chose “@plutokiller” for his Twitter handle.
So what does Brown think about the proposed new definition? You be the judge.
“Oh god the stupid Pluto stories are back. Yes, someone has proposed making Pluto a planet again. No, nothing is changed or new,” Brown tweeted Tuesday (Feb. 21). “Also, I should note, that proposal would make the moon a planet. Which is about 500 years out of date. But, ok #MakeTheMoonGreatAgain,” he added in another tweet.
The 48th Lunar and Planetary Science Conference runs from March 20 through March 24. It should be lively!
On Wednesday (Feb. 22), an international team of astronomers announced that seven planets about the size of our own orbit TRAPPIST-1, a tiny, cool star that lies just 39 light-years from Earth. Three of these planets orbit in the star’s “habitable zone,” where lakes, rivers and oceans could exist on a world’s surface, but all seven could potentially harbor surface water, given the right atmospheric conditions, discovery team members said.
“With this discovery, we’ve made a giant, accelerated leap forward in the search for habitable worlds, and life on other worlds, potentially speaking,” Sara Seager, a planetary scientist at the Massachusetts Institute of Technology, said during a news conference Wednesday.
The find is exciting for several reasons, according to Seager, who is not part of the discovery team. First of all, with multiple potentially water-bearing worlds, the TRAPPIST-1 system is a promising candidate to host life — even if researchers don’t have a completely accurate understanding of its habitable zone (also known as “Goldilocks zone”).
“You could say, colloquially, it’s like in this planetary system, Goldilocks has many sisters,” Seager said.
Furthermore, about 15 percent of the stars in the sun’s neighborhood are ultracool dwarfs like TRAPPIST-1, which is only slightly larger than Jupiter. Many of these nearby dwarfs may host rocky, potentially habitable planets, if TRAPPIST-1 is any guide.
“With this amazing system, we know there must be many more potentially life-bearing worlds out there, just waiting to be found,” Seager said.
Finding such worlds is just the beginning. TRAPPIST-1 is close enough to Earth that astronomers will soon be able to characterize the seven planets’ atmospheres in detail — a key step in gauging the worlds’ habitability — and probe them for oxygen, ozone, methane and other potential signs of life. Indeed, NASA’s $8.8 billion James Webb Space Telescope will likely start doing just that shortly after it launches in late 2018.
Baltimore. Lewis is not part of the TRAPPIST-1 discovery team, either, though she was co-leader of a group that used NASA’s Hubble Space Telescope to begin studying the atmospheres of two of the planets in the system. (Researchers first announced the detection of three planets around TRAPPIST-1 in 2016; the new discovery confirmed two of those previously spotted worlds, and bumped the total planet tally to seven.)
Three huge ground-based observatories scheduled to come online in the early to mid-2020s — the European Extremely Large Telescope, the Giant Magellan Telescope (both in Chile) and the Thirty Meter Telescope (in Hawaii) — should also be able to study the atmospheres of nearby planets such as the TRAPPIST-1 worlds, the builders of the telescopes have said.
There should be many planets for them to investigate. For example, the team behind the new TRAPPIST-1 discovery will soon begin hunting for planets orbiting 1,000 nearby ultracool dwarfs, in a project called SPECULOOS (Search for Habitable Planets Eclipsing Ultra-cool Stars). And in 2018, NASA plans to launch the TESS (Transiting Exoplanet Survey Satellite) mission, which agency officials have said will likely find thousands of worlds circling stars in the sun’s neck of the woods.
“TRAPPIST-1 is the most exciting one so far, but we hope to have many more of these, and lots of chances to find signs of life in the future,” Seager said.
Wouldn’t it be great if, when landing a robotic mission on another planet, the lander or rover could just scoop a sample, drop it into a chemical analyzer and get a “positive” or “negative” result for extraterrestrial life?
Well, this chemistry test isn’t so farfetched and scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., are working on a method that is 10,000 times more sensitive than any other method currently employed by spacecraft.
Focused on the detection of specific types of amino acid tied to life, the researchers propose mixing a liquid sample collected from the surface of an alien world with a chemical known as a liquid reagent. Then, by shining a laser across the mixture, the molecules it contains can be observed moving at different speeds when exposed to an electric field. From this, the different molecules can be identified and the whole thing can be done autonomously, no humans required.
The method known as “capillary electrophoresis” can be used to detect many different types of amino acids simultaneously.
“Our method improves on previous attempts by increasing the number of amino acids that can be detected in a single run,” said researcher Jessica Creamer in a statement. “Additionally, it allows us to detect these amino acids at very low concentrations, even in highly salty samples, with a very simple ‘mix and analyze’ process.”
The team has already tested the method on water taken from Mono Lake in California — a mass of salty water with an extreme alkalinity — and simultaneously analyzed 17 different amino acids.
“Using our method, we are able to tell the difference between amino acids that come from non-living sources like meteorites versus amino acids that come from living organisms,” said Peter Willis, the project’s principal investigator also at JPL.
Molecules like amino acids come in two different “chiralties” that are mirror images of one another. Non-organic sources contain roughly equal “left-” and “right-handed” chirality amino acids, whereas amino acids from living organisms are predominantly left-handed — for life on Earth in any case. This differentiation can be detected by capillary electrophoresis.
This method is exceedingly powerful for several reasons. Currently, NASA is putting great efforts into looking for habitable environments on Mars. We know that the Red Planet used to be a very wet place and there’s evidence that suggests very briny sources of liquid water exists to this day. If life has ever taken hold on Mars, and if a future mission can directly sample this salty, toxic water, it’s sensitive chemical analyses such as this that will likely track it down.
Also, in the future, it is hoped that a mission may be sent to Jupiter’s moon Europa, which is known to possess an extensive subsurface ocean. Many components for life as we know it exists on Europa, so if a robotic mission can be sent to the moon’s ice-encrusted surface, or even dropped into the ocean itself, finding out whether there’s life elsewhere in the solar system could be one simple chemistry test away.
The Milky Way is littered with a vast diversity of planets: giants that blur the line between planet and failed-star brown dwarf; tiny worlds similar in size to Earth’s moon; planets that take 100,000 years to orbit their suns or whip around in hours; lava worlds; ice worlds; and planets that circle multiple suns or whirling pulsars.
Scientists find them by watching stars that wobble, change gravity, vary in color or dip slightly in brightness. (This last strategy is employed by the most prolific planet hunter of all time, NASA’s Kepler space telescope.) And someone needs to keep track of them all.
Rachel Akeson, deputy director at the NASA Exoplanet Science Institute, leads the space agency’s Exoplanet Archive, which is tasked with cataloging the ever-growing horde of planets known to exist outside the solar system.
“In 2011, there were about 700 [confirmed exoplanets]; now we’re over 3,400,” Akeson told Space.com. “In the next five years, there’s going to be tens of thousands.”
Those newly discovered exoplanets will come courtesy of various space observatories that are operating now or will come online soon. For example, the European Space Agency’s Gaia mission is precisely measuring the positions of 1 billion Milky Way stars, and the work should allow astronomers to notice movements caused by the pull of many orbiting planets.
And NASA’s Transiting Exoplanet Survey Satellite (TESS) is scheduled to launch to 2018 to search for planets all over the sky circling stars relatively close to the sun, using the same method as Kepler.
NASA’s Exoplanet Archive will house them all; the database, which was made publicly accessible in 2013, lets researchers and enthusiasts understand the distribution and properties of planets found thus far as they come in, as well as data about the stars they orbit and planet “candidates” that have yet to be confirmed. The archive also generates graphs from the latest information to show exoplanet trends.
Right now, a big part of the Exoplanet Archive takes the shape of a large interactive table of confirmed planets, which have been checked and double-checked by the authors to make sure they’re not flukes in the data. Most of the planets aren’t directly imaged but rather detected via their effects on their parent stars, and confirmations can come from observation by various methods or by a strong pattern of “transits” across their stars.
The archive also hosts data about the stars’ light curves when they’re available, showing their brightening and dimming, as well as Kepler data that has not been confirmed as a planet’s signature. It keeps a list of false positives, too, and the list is always in flux; additions and changes in status are implemented continuously.
“Things can go in and then come back out,” Akeson said. “And I think in one case, something went in, came out and has gone back in. There’s this series of papers in the literature — basically two groups arguing with each other via the papers — whether or not this is the planet signature versus another kind of signature.”
An exoplanet’s data is officially added only once it appears in a peer-reviewed publication.
As more and more planets come in, researchers can use the archive to begin to understand the galaxy’s overall distribution of planets. Different methods of detection find different kinds of planets. For instance, transit measurements from Kepler or TESS are more likely to find planets that orbit close to their stars, and Gaia should generally find planets that orbit farther away, Akeson said. With current technology, systems like Earth’s would still be hard to find, and so researchers don’t know how common they are.
“We have no system that looks like the solar system yet, where you have these small, rocky planets on the inside and then several gas giants on the outside,” Akeson said. “We’re now getting to the point where we’re starting to see things that are true Jupiter analogues, but the Earth analogues are very hard to find still.”
Going forward, a thorough survey could help researchers understand how planetary systems evolve and why our solar system is the way it is, instead of featuring mini-Neptune and super-Earth planets like researchers have found in other star systems.
As scientists continue to discover exoplanets, the catalogue will keep growing. The archive’s researchers are talking to groups of users to determine the most helpful way to display the information, and planning the best ways to wrangle and verify the new waves of planets, Akeson said.
“We are going to have to keep up,” she said.
This planet, known as Wolf 1061c, resides in the “habitable zone” of its host star, that just-right range of distances where liquid water could theoretically exist on a world’s surface. But it’s far from clear if Wolf 1061c could actually support life as we know it, study team members said.
For starters, Wolf 1061c — which circles a star located just 14 light-years from Earth’s sun — lies at the inner edge of the habitable zone, similar to where Venus is in Earth’s solar system. Venus has a hellish environment today, with surface temperatures reaching nearly 900 degrees Fahrenheit (480 degrees Celsius). [Gallery: The Strangest Alien Planets]
Venus likely had oceans on its surface in the past, but was so close to the sun that the heat made all the oceans evaporate. The water vapor assisted in trapping heat, contributing to Venus’ runaway greenhouse effect.
Something similar may have happened on Wolf 1061c, said the new study’s lead author, Stephen Kane, of San Francisco State University.
Wolf 1061c is “close enough to the star where it’s looking suspiciously like a runaway greenhouse,” Kane said in a statement.
Kane and colleagues studied Wolf 1061c’s parent star in detail using the Center for High Angular Resolution Astronomy array, which is located at the Mount Wilson Observatory in California. The researchers’ detailed measurements allowed them to better characterize the star’s habitable zone and the conditions that planets in the system likely experience. (Wolf 1061c is one of three worlds known to circle the star; all are “super-Earths,” planets slightly larger than Earth.)
“The Wolf 1061 system is important because it is so close [to Earth], and that gives other opportunities to do follow-up studies to see if it does indeed have life,” Kane said.
The team found that Wolf 1061c’s orbit varies at a faster rate than that of Earth, and this likely leads to greater climatic variations than Earth experiences
“It could cause the frequency of the planet freezing over or heating up to be quite severe,” Kane said.
So it’s unknown whether or not Wolf 1061c actually is habitable, study team members said. Getting to the bottom of this question may require more-advanced telescopes than are currently in operation, the researchers added.
One future instrument that should help is NASA’s $8.8 billion James Webb Space Telescope, which is scheduled to launch in late 2018 and succeed the Hubble Space Telescope, Kane said. Webb is expected to reveal the composition of nearby exoplanet atmospheres in detail.
Findings from the new study will appear in the next issue of the Astrophysical Journal. A preprint version is available now on the website arXiv.
Nearly two years after its historic encounter with the dwarf planet Pluto, NASA’s New Horizons spacecraft is getting ready for its next big adventure in the icy outskirts of the solar system.
Now, the spacecraft is on its way to a small, ancient object located about 1 billion miles (1.6 billion kilometers) beyond Pluto in the Kuiper Belt. This distant region surrounds the solar system and is filled with trillions of icy rocks that have yet to be explored. The new target was discovered by the Hubble Space Telescope in June 2014, and it was dubbed 2014 MU69.
Pluto, which officially lost its planetary status shortly after New Horizons launched in 2006, is also a Kuiper Belt object (KBO), and the largest of its kind. New Horizons became the first spacecraft to visit the Pluto system when the probe flew by the dwarf planet and its moons on July 14, 2015. [
It took the spacecraft about 16 months to beam back all of its data from the Pluto flyby, and planetary scientists have had a ball with that data.
The New Horizons flyby of the Pluto system was completely successful, and now we’ve got all the data on the ground and we’re putting a bow around it,” Alan Stern, the New Horizons principal investigator at Southwest Research Institute, said in a Facebook Live event on Thursday (Jan. 19).
Thanks to New Horizons, scientists now have a global map of Pluto and the most detailed images yet of the dwarf planet’s bizarre, mountainous landscape and icy volcanoes. Tall mountain ranges seen on Pluto also suggest recent geological activity on the dwarf planet’s surface.
New Horizons additionally beamed back a gorgeous photo of a huge, heart-shaped basin (unofficially called “Tombaugh Regio”) that quickly became Pluto’s most famous feature, taking the internet by storm and gracing the front page of hundreds of newspapers worldwide. The New Horizons science team has said Pluto’s “heart” seems to indicate the presence of a subsurface ocean.
The Pluto flyby also provided an opportunity to study Pluto’s moons, particularly Charon. Researchers discovered that Charon and Pluto are both tidally locked, meaning the same side of the moon always faces the dwarf planet and vice-versa. As a result, Pluto’s heart is always facing Charon. A giant red spot discovered on Charon’s surface revealed that the moon is taking some of its atmosphere from Pluto.
“One thing that we discovered is that small planets can be just as complex as big planets, and that really blew away our expectations,” Stern said, adding that all the new findings from Pluto “wet our appetite for future exploration of the Kuiper Belt.”
While the team continues to analyze the plethora of data — something that could go on for decades — it’s also busy planning for the next big stage of the mission, the flyby of 2014 MU69. That will occur in January 2019.
Pluto is the largest object known to exist in the Kuiper Belt, but MU69 is much smaller and more representative of the trillions of other KBOs, Kelsi Singer of the New Horizons science team told Space.com. Pluto is comparable to the size of North America at 1,475 miles (2,370 km) in diameter, while MU69 is less than 30 miles (about 45 km) across.
But MU69 isn’t just any old KBO. Singer said that the object “has a special kind of orbit that makes it possibly a type of object that is primordial and left over from early solar system formation. So we think that we’ll be able to look at what the building blocks of the solar system were like by going to this special object that has a special orbit.”
Part of the rationale for choosing MU69 as the next target was that it had a good location given the amount of fuel left on the New Horizons spacecraft.
“MU69 turned out to be really interesting, but we also had limited options,” Singer said. Using the Hubble Space Telescope, “we were searching the area of space where we had enough fuel left in the spacecraft to get to any objects that were there,” she said. Three good potential targets were located, but the other two “were just on the edge of where [the spacecraft] had enough fuel to get to.”
New Horizons runs on a radioactive plutonium power supply that could keep the spacecraft going through the mid-2030s, Glen Fountain, the New Horizons encounter project manager at Johns Hopkins University’s Applied Physics Laboratory, said during the Facebook Live event.
But after the 2019 flyby of MU69, the spacecraft probably won’t have much fuel left for special maneuvers, Singer said. “We won’t be able to switch directions, but we’ll still keep going out. It’s possible that we’ll be able to observe some other objects, but we haven’t identified any of them yet. So we’re going to keep an eye out to see what we can find.”
For now, the team will remain focused on planning the MU69 flyby and sifting through data from Pluto. The researchers need to plan the spacecraft’s every move far ahead of time; because of a 6-hour delay in communications with the distant spacecraft, they won’t be able to tell the probe what to do in real time. Instead, the team must program New Horizons at least several months in advance to do every observation and data transmission.
The spacecraft will take photos of MU69 along the way, starting out with pictures of a single-pixel speck from afar, Singer said. During the flyby, New Horizons will be able to get even closer to MU69 than it did with Pluto, because the small object has much less gravity. This means that the photos of MU69 will have a higher resolution than the photos of Pluto. Singer said that’s something she and the team look forward to seeing.
In April, New Horizons will be halfway to MU69 from Pluto, with 21 months of spaceflight left to go.
Microbes that rank among the simplest and most ancient organisms on Earth could survive the extremely thin air of Mars, a new study finds.
The Martian surface is presently cold and dry, but there is plenty of evidence suggesting that rivers, lakes and seas covered the Red Planet billions of years ago. Since there is life virtually wherever there is liquid water on Earth, scientists have suggested that life might have evolved on Mars when it was wet, and life could be there even now.
“In all the environments we find here on Earth, there is some sort of microorganism in almost all of them,” said Rebecca Mickol, an astrobiologist at the Arkansas Center for Space and Planetary Sciences at the University of Arkansas in Fayetteville, and the lead author of the study. “It’s hard to believe there aren’t other organisms out there on other planets or moons as well.”
Mickol and her team detailed their findings in the paper “Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars,” which was published in the journal Origins of Life and Evolution of Biospheres.
Previous research detected methane, the simplest organic molecule, in the Martian atmosphere. While there are abiotic ways to produce methane — such as volcanic activity — much of this colorless, odorless, flammable gas in Earth’s atmosphere is produced by life, such as cattle digesting food.
“One of the exciting moments for me was the detection of methane in the Martian atmosphere,” Mickol said. “On Earth, most methane is produced biologically by past or present organisms. The same could possibly be true for Mars. Of course, there are a lot of possible alternatives to the methane on Mars and it is still considered controversial. But that just adds to the excitement.”
On Earth, microbes known as methanogens produce methane, also known as natural gas. Methanogens typically live in swamps and marshes, but can also be found in the guts of cattle, termites and other herbivores, as well as in dead and decaying organic matter.
Methanogens are among the simplest and most ancient organisms on Earth. These microorganisms are anaerobes, meaning they do not require oxygen. Instead, they often rely on hydrogen for energy, and carbon dioxide is the main source of carbon atoms they use in creating organic molecules.
Methanogens contained in these test tubes, which also contained growth nutrients, sand and water, survived when subjected to Martian freeze-thaw cycles.
The fact that methanogens neither require oxygen nor photosynthesis means they could live just beneath the Martian surface, shielded from harsh levels of ultraviolet radiation on the Red Planet. This could make them ideal candidates for life on Mars.
However, the area just below the surface of Mars is exposed to extremely low atmospheric pressures, normally considered inhospitable to life. The surface pressure on Mars on average ranges from one-hundredth to one-thousandth that of the surface pressure of Earth over the course of the Martian year, too low for liquid water to last on the surface. In such thin air, water easily boils. (In contrast, the pressure at the highest point on Earth’s surface, the top of Mount Everest, is about one-third that of Earth’s surface pressure at sea level.)
To see if methanogens might survive such extremely thin air, Mickol and Timothy Kral, the senior author of the study and an astrobiologist at the University of Arkansas at Fayetteville, experimented with four species of methanogens. They included: Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, and Methanococcus maripaludis. Previous experiments on these four species over the course of more than 20 years generated a lot of data on these organisms and their rates of survival in simulated Martian conditions.
The more recent set of experiments, which took about a year, involved growing the microbes in test tubes within liquids as a proxy for the fluids potentially flowing through underground Martian aquifers. The microbes were fed hydrogen gas, and the liquids were covered with cotton swabs, which in turn were covered with dirt simulating what might be found on the Martian surface. The insides of each test tube were then subjected to low pressures.
Oxygen kills these methanogens, and maintaining a low-pressure, oxygen-free environment “was a difficult task,” Mickol said. Moreover, water evaporates quickly at low pressure, which can limit how long the experiments can last and can also clog the vacuum system with water.
Despite these problems, the researchers found that these methanogens all survived exposure of lengths varying from 3 to 21 days at pressures down to roughly six-thousandths of Earth’s surface pressure. “These experiments show that for some species, low pressure may not really have any effect on the survival of the organism,” Mickol said.
The scientists are also measuring methane to see whether methanogens are actively growing at low pressure and producing methane.
“The next step is to also include temperature,” Mickol said. “Mars is very, very cold, often getting down to -100ºC (-212ºF) at night, and sometimes, on the warmest day of the year, at noon, the temperature can rise above freezing. We’d run our experiments just above freezing, but the cold temperature would limit evaporation of the liquid media and it would create a more Mars-like environment.”
Mickol stressed that these experiments do not prove life exists on other planets. “That being said, with the abundance of life on Earth, in all the different extremes of environments found here, it’s quite possible there exists life — bacteria or tiny microorganisms — somewhere else in the Universe,” she said. “We’re just trying to explore that idea.”
This research was supported by the Exobiology & Evolutionary Biology element of the NASA Astrobiology Program.
As NASA’s Mars rover Curiosity makes its way up the central peak of Gale Crater, it has been gathering evidence from ancient lake beds and long ago groundwater environments that are promising for life.
Scientists in charge of the mission gave an update of their findings Dec. 13 at the American Geophysical Union’s annual fall meeting in San Francisco, saying the landing site at Gale Crater had exceeded their expectations. They said they have “hit a jackpot” of exposed mineral layers as the rover moves up Mount Sharp, offering a glimpse into the geologic history of the site and how global environmental conditions might have changed on Mars over the course of millions of years.
“We see all of the properties in place that we really like to associate with habitability,” said mission team member John Grotzinger, a geologist at the California Institute of Technology in Pasadena. “There’s nothing extreme here. This is all good for habitability over time.”
Gale Crater is the lowest point within thousands of kilometers in all directions, and scientists believe water once pooled there into a lake and also seeped underground. They believe the groundwater may have persisted even after the surface water dried up, offering a prolonged period for life to persist. So far, there’s been no evidence of life, microbial or otherwise, but if Mars did once support living organisms, this would have been one of the most likely spots on the Red Planet.
After traveling 9 miles (15 kilometers) from its landing site, Curiosity has now entered a critical part of its mission, boring into the exposed mudstone every 82 feet (25 meters) as it goes uphill to progressively younger layers and analyzing the contents of the fractured rock.
“You might think mudstones would be boring, but they’re definitely not,” said Curiosity deputy project scientist Joy Crisp, of NASA’s Jet Propulsion Laboratory in Pasadena.
One clue to the changing conditions is the type of iron oxide present in the rocks. The lower, more ancient layers appear to be dominated by the mineral magnetite, indicating less weathering in the environment. Meanwhile, the upper rock layers show a greater amount of oxidizing hematite, a sign of chemical reactivity that would indicate a more acidic environment, though not extremely so.
“It’s acidic, but never super-acidic. It’s totally the kind of environment where an acidophilic organism could enjoy it,” said Grotzinger.
Curiosity has also detected the element boron for the first time on Mars, and it’s appearing within mineral veins that are mainly comprised of calcium sulfate. On Earth, boron — or rather, a certain form of it — is a component in the formation of RNA, usually found in arid sites with much-evaporated water like in Death Valley National Park in California.
“The only problem with this is, we don’t know what form of boron it is,” said Patrick Gasda, of Los Alamos National Laboratory in New Mexico. If the kind of boron present on Mars is found to be similar to what we see on Earth, that would be a strong sign that the ancient groundwater that formed these veins would have been between 32 degrees and 140 degrees Fahrenheit (0 to 60 degrees Celsius) and a neutral-to-alkaline pH, making the location entirely plausible for life, researchers said
The boron was identified by Curiosity’s ChemCam instrument, a laser-shooting device that vaporizes materials and then uses a spectrograph to analyze the elemental composition of the resulting plasma of super-heated ions and electrons. The scientists propose that the boron was deposited there by moving water, suggesting a dynamic system in which minerals and elements interacted with groundwater and surface water as it moved through the landscape.
“We are seeing chemical complexity indicating a long, interactive history with the water,” said Grotzinger. “The more complicated the chemistry is, the better it is for habitability. The boron, hematite and clay minerals underline the mobility of elements and electrons, and that is good for life.”
The scientists also gave a brief update on how Curiosity is faring. The rover continues to operate, although it has faced some recent malfunctions, including a break in the motor of the drill feed, a piece responsible for moving the drill up and down during rock sampling. Mission scientists are currently troubleshooting that problem with the hope of keeping the Curiosity drill going, though the rover has already well exceeded its nominal two-year mission that began in 2012.
Mars may appear red when viewed from Earth, but NASA’s Curiosity rover has captured an up-close photo of the planet’s mountainous landscape, with purple-colored rocks littered across the foreground.
This remarkable new photo was captured near the base of Mars’ Mount Sharp. The image’s three frames were taken by Curiosity’s Mast Camera (Mastcam)on Nov. 10.
“Variations in color of the rocks hint at the diversity of their composition on lower Mount Sharp. The purple tone of the foreground rocks has been seen in other rocks where Curiosity’s Chemical and Mineralogy (CheMin) instrument has detected hematite,” or a type of iron-oxide mineral, NASA officials said in a statement. “Winds and windblown sand in this part of Curiosity’s traverse and in this season tend to keep rocks relatively free of dust, which otherwise can cloak rocks’ color.”
Mount Sharp rises 3 miles (5 kilometers) from the center of Mars’ 96-mile-wide (154 km) Gale Crater. After arriving at the crater in 2012, Curiosity found evidence that suggested that the area could have supported microbial life in the ancient past.
In addition to the purple rocks in the foreground, the images from Curiosity capture higher layers of Mount Sharp. The rover will continue to traverse these slopes throughout the rest of its mission.
This uphill trek began in October at the orange-colored rocks of the Murray formation, near the base of Mount Sharp. Next the rover will climb upward to the Hematite Unit, followed by the Clay Unit and the rounded hills of the Sulfate Unit — which is Curiosity’s highest planned destination. Studying the composition of these different rock layers can help scientists learn more about Mars’ past.
The images have a white-balanced color adjustment that resembles how rocks and sand would appear under daytime lighting conditions on Earth. This helps geologists who study the rocks recognize color patterns that they are familiar with on Earth, NASA officials said in the statement.
Ellen Stofan, current NASA chief scientist, said sending humans to Mars would be a powerful step in the search for life beyond Earth.
“I am someone who believes it is going to take humans on the surface [of Mars] … to really get at the question of not just did life evolve on Mars, but what is the nature of that life,” Stofan said at a scientific workshop in Irvine, California, hosted by the National Academy of Sciences. “To me, we’re going to go Mars because Mars holds the answers to such fundamental scientific questions that we’re trying to ask.”
The workshop, titled “Searching for Life Across Space and Time,” drew together leading scientists who are, through various avenues, working to find signs of alien life in Earth’s solar system and beyond. Stofan has argued before for the scientific benefits of a human mission to the Red Planet.
Stofan said she believes strongly in sending humans to Mars to search for signs of life because humans can perform tasks that would be difficult for a rover. Humans can operate drills that could go deeper than the few inches plumbed by the Curiosity rover, or even beyond a depth of 6.5 feet (2 meters), which is the expected limit for the ExoMars rover, a joint mission between the European Space Agency and Russia’s Roscosmos. Humans could potentially explore more locations than a rover could and perform deeper scientific analysis than what is possible using a remote, robotic scientific laboratory, she said.
“We now know water was stable for long periods of time on the surface [of Mars], and Mars’ potential for habitability, I think, is huge,” Stofan said. “I do believe that we need … brave people to spend time on Mars, to have a scientific laboratory on Mars, to do the work that we need to do to truly understand what life on Mars tells us about life beyond Earth.”
Multiple sessions at the meeting focused on the search for signs of ancient life or even present-day life on Mars. Today, the surface of the Red Planet appears to be inhospitable to the kind of life that exists on Earth, mainly because liquid water exists only in very small amounts, and is extremely salty. Other factors would also make life hard on the Red Planet, including high doses of space radiation (because Mars lacks the protective atmosphere and magnetic field that Earth has),and wildly oscillating surface temperatures: During the Martian summer months, the surface of the planet might be 70 degrees Fahrenheit (21 degrees Celsius) during the day, but plummet to minus 100 F (minus 73 C) at night.
There are examples of extreme life-forms on Earth that can survive in some of those conditions, including frigid temperatures and exposure to high doses of radiation. However, liquid water is a necessity for all known Earth-based life-forms. But based on the discovery of brines on the surface of Mars, some people think it’s possible that life exists on the Red Planet today. With that in mind, some people are concerned that sending rovers and humans to Mars could risk contaminating the planet with Earth-based microbes.
Right now, NASA has plans that could allow scientists to bring rock samples back to Earth from Mars, Stofan said. An in-depth analysis of a Martian rock might help the scientific community make a more informed decision about whether life likely exists on Mars today, and thus what steps would be needed to prevent biological contamination from a human visit to the Red Planet, Stofan said.
“I think these are questions that should be in the hands of the science community via the [NAS],” she said.
Stofan briefly addressed concerns about whether NASA could actually pull off its plan to send humans into orbit around Mars by the early 2030s and onto the planet’s surface by the late 2030s, saying that she is an “incredible optimist on this
The scientist added that she has also heard people say that there is “no real reason” to send humans to the surface of Mars (as opposed to robotic missions), and she called on members of the science community to “speak up” if they disagree.
The scientific interest in Mars extends beyond NASA. The European, Indian and Chinese space agencies are all sending probes or rovers to Mars. Private companies (primarily Elon Musk’s SpaceX) are also working on plans related to Mars. Someone in the audience asked Stofan if she thought the global scientific community is engaged in a sort of “soft space race” to Mars.
“I really don’t see it as a soft race. I see it as this amazing confluence of interests,” Stofan said. “I think Mars has incredible public appeal. …. It engages the public in a way that very few other things do, which is great.
“I think this is a great opportunity to sort of explore Mars with humans in a very different way than we went to the moon with humans, where it really was a race. [Mars], I think, is going to be motivated by cooperation and collaboration. That’s how we’re going to move forward, rather than competition.”
There’s water, water everywhere on the dwarf planet Ceres according to new research. New observations have provided direct evidence that in water ice is ubiquitous in the surface and shallow subsurface of this massive asteroid.
Ceres is the largest object in the asteroid belt that lies between Mars and Jupiter, and has long been suspected of containing significant amounts of water — estimates projected up to 30 percent of its total mass. Evidence has pointed to water ice being mixed with the rock on Ceres’ surface, and in a few rare cases, more concentrated patches of exposed ice have been found. Ceres has even belched up plumes of water vapor.
The new results come from a global map of Ceres showing the distribution of hydrogen, which can then be used to infer the presence of water. The data supports the theory that Ceres’ water content separated from the rock content, and formed an ice-rich crust on the dwarf planet. The fact that so much water is still present on Ceres “confirms predictions that water ice can lie for billions of years within a meter of the surface,” the authors write in the new paper detailing the findings
The global map was created using an instrument on NASA’s Dawn probe, which is currently orbiting the dwarf planet, called the Gamma Ray and Neutron Detector (GRaND). This instrument detects two kinds of particles: neutrons, one of the particles that make up atoms, and gamma rays, very high-energy light. When cosmic rays (very high-energy particles from space) crash into the surface of the dwarf planet, the collision can create a spray of debris particles, including neutrons and gamma rays. But the debris isn’t random; the characteristics of some of those gamma rays and neutrons can provide information about the chemical composition of the surface of Ceres and to certain depths below the surface. So scientists looking at data from GRaND can learn about the abundance of elements, including potassium, iron and hydrogen on the surface of Ceres, and to a depth of about 3 feet (1 meter).
The instrument cannot directly detect water molecules, but that can be inferred from the data, according to the authors. One way this is done is with computer models, which can recreate the evolution of Ceres, producing various possible outcomes that show how those elements (and water) would be distributed today.
Comparing the models with the new map shows that water ice on Ceres is concentrated near the poles: At high latitudes (past about 40 degrees in both hemispheres), water ice on the surface of Ceres and in the layers just under the surface may compose up to 27 percent of Ceres’ mass, according to the new research. Near the equator, the water ice concentration is much lower.
They researchers also compared the map of Ceres with a map of Vesta, another body in the asteroid belt. The data from those global maps show that Ceres has over 100 times more hydrogen than Vesta, and that the hydrogen is distributed more evenly over the surface. That indicates some kind of global process, which implies that water was (and still is) a large component of Ceres’ composition, according to the lead author of the new research, Thomas Prettyman, principal investigator for GRaND. Prettyman spoke at a news conference today (Dec. 15) at the annual meeting of the American Geophysical Union in San Francisco.
Prettyman also noted that Ceres’ composition has been compared with a family of meteorites called carbonaceous chondrites. These rocks, like most asteroids in the asteroid belt, have evolved very little since the early days of the solar system. But the new map (which also shows the distribution of iron and potassium on Ceres) shows some key differences between Ceres and these meteorites.
“If you look at the elemental composition of Ceres, it bears some resemblance to the carbonaceous contrite meteorites,” Prettyman said. “But there are differences that support the idea that ice and rock that came together and formed Ceres actually separated in the interior and were redistributed by processes like convection.”
It is possible that Ceres harbors a liquid ocean deep below its surface, but if that is the case, the ocean is likely composed of a very salty chemical mixture, with little or no water, according to Carol Raymond, deputy principal investigator of the Dawn mission, who also spoke at the news conference. Instead, the new results indicate Ceres’ water is largely stored in ice deposits near the surface.
A separate study appearing in the journal Nature and also released today revealed the presence of a concentrated patch of surface ice on Ceres, located in a regions cloaked in permanent shadow. But this and other patches of surface ice deposits are “rare,” according to the paper’s authors, and don’t add up to anywhere near the total amount of ice now thought to lie buried just under Ceres’ surface.
The Dawn probe entered into orbit around Ceres in March 2015. The spacecraft completed its primary mission in June, and continues to study Ceres as part of its extended mission.