Sent from my iPad
Begin forwarded message:
From: "Moon, Larry J. (JSC-EA411)" <larry.j.moon@nasa.gov>
Date: December 9, 2014 at 11:44:38 AM CST
To: "Moon, Larry J. (JSC-EA411)" <larry.j.moon@nasa.gov>
Subject: FW: NASA and Human Spaceflight News - Tuesday – December 9, 2014 + another Losses snapshot update
RETIREMENT JSC BJ111 FTP PORCHE, KARON 12/31/14 RETIREMENT JSC ER511 FTP WHEELOCK, CHARLES 01/02/15 RETIREMENT JSC EA551 FTP GLENN, MARTHA 01/02/15 RETIREMENT JSC AC111 FTP PHILLIPS, JEFFREY 01/31/15 NASA and Human Spaceflight NewsTuesday – December 9, 2014HEADLINES AND LEADSOrion Spaceship Comes Back to Shore After Making a SplashAfter two orbits around the planet and a successful splashdown in the Pacific, the Orion deep-space capsule has been returned to land. A NASA-Navy team retrieved the uncrewed capsule on Friday and brought it back to Naval Base San Diego on Monday aboard the USS Anchorage.The beginning of a new era—but which one?Jeff Foust – The Space ReviewNASA has an enviable ability to make the difficult look easy. Much of that has to do with technical competence, of course: engineers with the skills—and time and resources—to develop the systems needed to carry out the mission at hand. Part of that, though, has to do with messaging as well, communicating the difficulty of that mission. Recall, for example, the landing of Curiosity on Mars in 2012: a feat described by NASA as very risky through its "Seven Minutes of Terror" video, but one that went off almost exactly as planned.NASA and Houston hospital work on spacesuit issueJuan A. Lozano – Associated PressThe empty spacesuit that sat on the operating table in a lab at Houston Methodist Hospital's research institute made for an unusual patient.Editorial | Give Cost-cutting a ChanceSpaceNews EditorExcess infrastructure and duplicative activities are an unnecessary budgetary drain that NASA can ill afford these days.Giant Crater on Mars Was Once a Vast Lake, Curiosity Rover ShowsMike Wall - Space.comA giant crater on Mars may have been able to support microbial life for millions of years in the ancient past because it was once a huge lake of water, new results from NASA's Curiosity rover suggest.Mars apparently had massive lake, NASA's Curiosity rover findsAmina Khan – Los Angeles TimesThe surface of ancient Mars may have been dotted by vast lakes that lasted long enough to give microbial life a chance to emerge on the Red Planet, NASA scientists said Monday.Looking to Mars to Help Understand Changing ClimatesDennis Overbye – The New York TimesTen thousand times a hundred thousand dusty years agoWhere now it stands the Plain of Gold did once my river flow.It stroked the stones and spoke in tongues and splashed against my face,Till ages rolled, the sun shone cold on this unholy place.That was the planet Mars as channeled by the folk singer and science writer Jonathan Eberhart in "Lament for a Red Planet."COMPLETE STORIESOrion Spaceship Comes Back to Shore After Making a SplashAfter two orbits around the planet and a successful splashdown in the Pacific, the Orion deep-space capsule has been returned to land. A NASA-Navy team retrieved the uncrewed capsule on Friday and brought it back to Naval Base San Diego on Monday aboard the USS Anchorage."This mission exemplifies the U.S. Navy commitment to the research and development of technologies and techniques to ensure the safety of human spaceflight support," said the ship's commanding officer, Capt. Michael McKenna. "I could not be more proud of my crew."Aboard the Orion capsule are dozens of sensors that recorded all kinds of data on the craft's performance and the radiation it encountered — a major risk during any extended trip in space. Orion is meant to be a crewed, reusable spaceship, and with luck it'll be heading to Mars in the 2030s — so it's important for its engineers to consider the comfort and safety of its future occupants.Over the next couple of weeks, NASA will truck the capsule 2,500 miles cross-country to Kennedy Space Center. A detailed analysis of the spacecraft and the data it recorded will be factored into the preparations for Orion's next robotic test flight — a trip around the moon and back that's expected to take place in 2018.The beginning of a new era—but which one?Jeff Foust – The Space ReviewNASA has an enviable ability to make the difficult look easy. Much of that has to do with technical competence, of course: engineers with the skills—and time and resources—to develop the systems needed to carry out the mission at hand. Part of that, though, has to do with messaging as well, communicating the difficulty of that mission. Recall, for example, the landing of Curiosity on Mars in 2012: a feat described by NASA as very risky through its "Seven Minutes of Terror" video, but one that went off almost exactly as planned.The same is true for Orion. In the days and weeks leading up to Friday's flight, NASA officials emphasized that this was a test flight, and things could go wrong. "I did want to remind people that this is important, it's a test flight," said NASA Orion program manager Mark Geyer at a prelaunch briefing at the Kennedy Space Center. "We are pushing on the systems to make sure that they work as we expect."By Friday afternoon, after Orion completed its four-and-a-half-hour test flight known as Exploration Flight Test 1 (EFT-1), those systems had worked almost exactly as expected. NASA piled on the superlatives to describe the mission, and understandably so. But as Orion moves one step closer to being able to take humans beyond low Earth orbit—something it won't be ready to do for perhaps seven more years, under current plans—exactly what it will be used for remains open to debate.EFT-1 by the bookThe purpose of the EFT-1 mission was to test many of Orion's key technologies that could not be effectively checked out on the ground. That included the various components jettisoned during flight, like its launch abort system; how its electronics responded to the radiation environment beyond low Earth orbit; and, perhaps most importantly, how its large heat shield survived reentry at velocities about 80 percent that of a return to the Moon (see "Orion's time finally arrives", The Space Review, December 1, 2014).Since Orion's intended launch vehicle, the Space Launch System (SLS), is still at least three years away from its first test flight, NASA and Orion prime contractor Lockheed Martin instead turned to the most powerful launch vehicle available: the Delta IV Heavy from United Launch Alliance (ULA). While EFT-1 was Orion's first flight, it would be the eighth for this launcher."You've heard about how this is a test flight, but from ULA's perspective, this isn't a test for us," said Ron Fortson, director of mission management for ULA, at a prelaunch briefing.So, ironically, it was problems with the tried-and-true Delta IV Heavy and not Orion that scrubbed the first EFT-1 launch attempt on Thursday, December 4. Winds just above allowable limits halted the countdown twice with less than four minutes before launch—the so-called terminal phase of the countdown—forcing controllers to step back and wait for winds to diminish. (There was also a ship briefly in restricted waters at the beginning of the launch window, but officials later said that even if the boat hadn't been there, winds would have halted the count.)Fortunately, the mission had an unusually long launch window, lasting more than two and a half hours, driven by lighting conditions both for launch and splashdown. What appeared to be a luxury, though, turned out to be a problem. As winds died down, controllers started a third launch attempt that morning. But, with a little over three minutes before liftoff, the countdown stopped again. Two "fill and drain" valves for liquid hydrogen propellant lines failed to close when commanded. Engineers couldn't resolve the problem before even that extended window closed, scrubbing the launch for the day.At a briefing after the scrub, a ULA executive said that the long launch window may have contributed to the problem. "We had some fuel valves on the common booster cores that had gotten cold and a little sluggish in their performance," said ULA chief operating officer Dan Collins. "This is something that we have seen on one previous [Delta IV] Heavy launch where we had a long window and had gone quite a ways into the window."Orion itself had no issues during the countdown, so NASA and its industry team set up to try the launch again Friday, December 5. Weather forecasts were less promising on Friday, with only a 40 percent chance of acceptable weather versus 70 percent on Thursday. Yet, despite some passing showers, winds and other weather conditions cooperated. With the valve problem resolved and no other technical issues with the rocket or spacecraft, the Delta IV Heavy lifted off at the beginning of its launch window, at 7:05 am Eastern time.The Delta IV Heavy placed Orion and its upper stage into a low Earth orbit, making one lap of the planet. At about 9:00 am Eastern time, the upper stage fired its engine again, boosting Orion onto an elliptical trajectory that took it to an altitude of 5,800 kilometers above the Earth—the highest a spacecraft designed to carry people has gone since the final Apollo mission to the Moon, Apollo 17, 42 years earlier. An hour before splashdown, the Orion command module separated from its service module and upper stage, preparing for reentry.All during that time, the flight was going as planned. Cameras in the spacecraft provided views of Earth from the unusual perspective of that elliptical trajectory, and telemetry indicated the spacecraft's systems were working properly. There was still, though, the drama of reentry: would the heat shield work as planned, would the parachutes deploy properly?Orion returned video up until reentry began and the plasma created by the heat of reentry temporarily blacked out communications, as expected. The uncertainty created by that communications blackout, though, was brief: both Orion and the fleet of aircraft and ships at the recovery site, about 1,000 kilometers southwest of San Diego in the Pacific Ocean, showed that the spacecraft survived the worst of reentry. Orion deployed its parachutes and splashed down at 11:29 am Eastern time.NASA immediately declared EFT-1 a success, repeatedly calling the flight "flawless" in coverage on NASA TV. "Every single system on this spacecraft functioned by the book from start to finish," said NASA's Rob Navias.At a post-flight briefing, program managers acknowledged that there were some glitches, albeit minor ones, with the flight. Mike Hawes, the Orion program manager at Lockheed Martin, said that a video processing unit on the spacecraft reset a couple times during the flight. That was not unexpected, he said, given the spacecraft's exposure to the lower Van Allen radiation belt during its flight, but it wasn't yet certain if those resets were caused by radiation exposure.There was also a problem with the airbags at the nose of Orion designed to upright the capsule if it ended up upside-down in the ocean after splashdown. One of the five airbags didn't deploy at all and another didn't fully inflate, Geyer said. "We know that the pyros fired and the [gas] bottles are empty," he said. However, the airbags weren't needed since the capsule landed and remained upright.Those problems, though, were relatively minor, and the spacecraft's major systems, including those at the heart of the test, appeared to work well. "We didn't see anything major, that's clear. It looks like it flew very close to what we expected," Geyer said.Asked later in the briefing if there were any surprises or "ah ha!" moments during the flight, Geyer responded, "There was a bit of an 'ah ha' that it worked so well."On to Mars (?)By the end of the day Friday, Orion was on board the primary recovery ship, the USS Anchorage. That ship is due to arrive back in San Diego on Monday, where Orion will be offloaded and given an initial checkout by engineers. Orion will then be trucked across the country back to the Kennedy Space Center (KSC), arriving by Christmas for further examinations.With that first flight in the books, NASA hopes to capitalize on the enthusiasm in the public, and even in the media (there were cheers and applause at times at the KSC press site from some members of the media there as Orion wrapped up its successful flight). "Thank you for catching that spirit that we all feel as human beings that we as a species are meant to push human presence into the solar system," said William Gerstenmaier, NASA associate administrator for human exploration and operations. "This is a first step in starting to do that."Maintaining that enthusiasm and momentum, though, may be a problem. Orion's next flight, on the inaugural launch of the SLS, will likely take place no sooner than 2018, despite earlier plans to launch in 2017. Geyer said last week that the work getting EFT-1 done, plus the inclusion of the European Space Agency, who will be building Orion's service module, means a launch by December 2017 is unlikely regardless of the status of the SLS. "We won't be there in December of '17," Geyer said.The program is in the midst of reviews leading to a development milestone known in NASA program management parlance as Key Decision Point C (KDP-C). That review will confirm the program's readiness to proceed, and also provide cost and schedule estimates for the program. SLS passed its KDP-C review in August, concluding that the rocket would be ready for its first launch no later than November 2018 at the 70-percent confidence level (meaning there was a 70-percent chance it would be ready by then.)Orion's KDP-C review, scheduled to be completed in May, will also provide cost and schedule estimates at the 70-percent confidence level, Geyer said, although Orion's estimates will go out to the second SLS mission, called Exploration Mission 2 (EM-2), the first Orion mission to carry a crew. NASA will provide cost and scheduled estimates for the first SLS/Orion mission, EM-1, as a part of that process as well.In the weeks leading up to the launch, Geyer and other officials had declined to give a full cost estimate for EFT-1. Geyer said at a prelaunch briefing that the cost of the launch vehicle itself, and components that could not be reused, was about $370 million. The Orion command module itself is not included in that total, since it is intended to be reused on a test of the spacecraft's abort system some time in 2018.Geyer explained that the cost of building the Orion spacecraft flying on EFT-1 is wrapped into the overall estimates for the cost of Orion design, development, test, and evaluation, or DDT&E, which will come out of the KDP-C review next year. "We don't split out DDT&E costs by flights. We don't calculate it that way," he said.When Orion is finally ready to carry humans—EM-2 is still scheduled for 2021, despite the likely slip of EM-1 from late 2017 to 2018—its initial missions remain unclear. NASA plans to eventually have Orion fly to an asteroid captured in lunar orbit as part of the Asteroid Redirect Mission (ARM), but it's likely that whatever asteroid is selected won't be in place in time for EM-2: current candidate objects would not be in place until the mid-2020s. NASA says it will still fly EM-2 as planned, perhaps into the same lunar orbit that ARM will use, and wait until EM-3 or -4 to send humans to the asteroid.A key decision for ARM is scheduled to come later this month, when NASA chooses between two options for carrying out the robotic portion of the mission. In "Option A," a spacecraft will redirect an entire asteroid, up to about ten meters in diameter, into lunar orbit. "Option B" would instead pluck a smaller boulder, only a few meters across, from the surface of a larger asteroid. NASA officials will choose between the two options at a December 16 meeting.ARM still faces skepticism from the scientific community and members of Congress. The latter could make their opinions known on ARM this week, when Congress takes up a spending bill for the remainder of fiscal year 2015.Eventually, NASA plans to use Orion on missions to send humans to Mars. But Orion is just one element of many needed to carry out such missions, and arguably one of the simplest. Habitation modules, landers, surface systems, and more are needed for such missions, but their development remains years away and, in many cases, face significant technical challenges.Some argue that spending money on Orion or SLS now is a misplaced use of resources. "The Orion program, along with the Space Launch System, actively assures that billions are lost that should go to the basic R&D that's really needed to get to Mars," said space industry analyst Charles Lurio."Everybody has been trying to get to Mars, and as [NASA chief scientist] Ellen Stofan always reminds me, we're always 30 years away. Well, we're not 30 years away any more," NASA administrator Charles Bolden said at a media event at the launch site December 3. Bolden, at the event, called EFT-1 not just a "big deal," but a "BFD.""Success breeds success, and success breeds expectations," he added. The success of EFT-1 launch week will certainly generate expectations for the future of human space exploration, but whether NASA and the nation can sustain those expectations, technically or fiscally, remains a central issue for the future of the agency.NASA and Houston hospital work on spacesuit issueJuan A. Lozano – Associated PressThe empty spacesuit that sat on the operating table in a lab at Houston Methodist Hospital's research institute made for an unusual patient.The bulky garment ended up in the state-of-the-art research lab after NASA sought innovative ways to pinpoint problems with its spacesuits in the wake of an Italian astronaut nearly drowning in his helmet during a 2013 spacewalk on the International Space Station. It happened when debris clogged a pump mechanism inside his spacesuit.NASA hopes the advanced imaging equipment in the lab, including a CT scanner attached to a robotic arm, can help it create 3-D pictures of its spacesuits that can be used to better diagnose malfunctions that might happen in the future.Luca Parmitano, the Italian astronaut who survived the harrowing experience with the spacesuit, said the work NASA and the hospital are doing is a step forward in preventing others from going through what he faced."I never thought about seeing a spacesuit lying on a surgeon's table. That is a first for me," said Parmitano, as he stood next to the spacesuit, which was not the same one he wore during the spacewalk.The imaging technology was demonstrated on the spacesuit during "Pumps & Pipes," an annual conference that brings three of Houston's biggest industries — medicine, energy and aerospace — together to discuss technologies that could be shared by the fields.Parmitano, an officer in the Italian Air Force, described to an audience at the event how the water began building behind his head in his helmet and later started to cover his ears, eyes and nose. He said he imagined a newspaper headline that read, "Italian astronaut drowns in space."Brian Macias, the spacesuit subsystem manager at NASA's Johnson Space Center in Houston, said a fan component that failed during the spacewalk was later examined with X-rays and N-rays, another form of radiography, but this gave engineers limited information."It's breaking new ground for us because we haven't used imaging a whole lot in finding out spacesuit anomalies," Macias said. "I see great potential."During a demonstration Monday at the conference, the robotic arm rotated the CT scanner around the spacesuit's helmet, creating red, black and white 3-D images that can allow engineers to look at the integrity of different components.Dr. Alan Lumsden, the medical director of the Methodist DeBakey Heart and Vascular Center who led the demonstration, said techniques used in endovascular surgery to examine problems with blood vessels are the same kind that can diagnose future problems with the spacesuits."Here is a situation where we are going to use our technology to potentially look at a problem that helps NASA," he said. "We really want to help as much as we can."Editorial | Give Cost-cutting a ChanceSpaceNews EditorExcess infrastructure and duplicative activities are an unnecessary budgetary drain that NASA can ill afford these days.It's a longstanding problem that has proved to be very stubborn. Civil service rolls are notoriously difficult to trim and NASA often encounters stiff congressional resistance when it tries to shutter outdated facilities or consolidate functions at a single center. Actually closing a center is a political nonstarter.NASA has had some success finding users for facilities it no longer needs. Examples include the lease of former space shuttle processing facilities at Kennedy Space Center in Florida to Boeing for its CST-100 commercial crew capsule and for the U.S. Air Force's Boeing-built X-37B spaceplane; and the more recent lease of a large aircraft hangar at Ames Research Center in Moffett Field, California, to a company owned by technology giant Google.In another encouraging development, a nearly 2-year-old initiative to reduce or eliminate duplication among NASA's 10 field centers appears to be kicking into high gear with the pending appointment of leaders to the agency's Technical Capabilities Assessment Team, or TCAT.These leaders will be tasked with finding efficiencies within several core agency capabilities at the field centers. Four such capabilities — Earth science, life science, aircraft operations and human factors — have been identified, with many more to follow.According to Lesa Roe, NASA's deputy assistant administrator, the four capabilities identified to date account for roughly $2.8 billion of the agency's nearly $18 billion annual budget, and employ some 10,000 civil servants and contractors. Overall, NASA employs 17,000 civil servants and 40,000 contractors.Addressing the NASA Advisory Council in November, Ms. Roe said the agency is targeting $550 million in annual savings across those four disciplines. She also noted that NASA has 98 mission operations centers and expressed hope that the associated costs can be cut by some 30 percent.Another activity likely to draw scrutiny is the process by which the centers often compete with one another to lead agency missions under programs like the Discovery series of planetary probes. "We are spending ... quite a bit of money annually, competing for our own money, as an agency," Ms. Roe said. "We compete centers against each other, and centers then hold on to capabilities we don't really need them holding on to just so they can compete. And that model has to be addressed."That's a healthy sentiment, although NASA must tread carefully. While Discovery and similar competitions incentivize centers to accumulate and retain duplicative capabilities, they also help ensure that selection officials receive the strongest set of proposals to choose from. NASA must look for ways to reduce duplication while preserving, to the extent possible, the competitive edge of its centers, which admittedly won't be easy.Another big question is how NASA's cost-cutting initiative will be received on Capitol Hill. Ms. Roe indicated that lawmakers have been receptive so far, but that could change once concrete proposals to reduce personal or transfer functions from a given center are laid on the table.Congress has contributed substantially to NASA's budget woes by funding pet projects and blocking center consolidation efforts. Lawmakers owe it to the U.S. space program and taxpaying public to give fair and objective consideration to the forthcoming proposals from the TCAT process.Giant Crater on Mars Was Once a Vast Lake, Curiosity Rover ShowsMike Wall - Space.comA giant crater on Mars may have been able to support microbial life for millions of years in the ancient past because it was once a huge lake of water, new results from NASA's Curiosity rover suggest.Curiosity found evidence for the crater lake on Mars in the 96-mile-wide (154 kilometers) Gale Crater, which the rover has been exploring since its August 2012 touchdown. Today, Gale Crater is a dry, stark landscape, but in the ancient past, runoff from the crater rim created a lake in which deposited sediments gradually built up Mount Sharp, a mountain that rises about 3.4 miles (5.5 km) high from the crater's center, mission scientists added."This lake was large enough it could have lasted millions of years — sufficient time for life to get started and thrive, sufficient time for lake sediments to build up and form Mount Sharp," Michael Meyer, Mars Exploration Program lead scientist at NASA Headquarters in Washington, said during a press conference today (Dec. 8). [Ancient Mars Could Have Supported Life: Photos]Building a mysterious mountainThe origin and evolution of Mount Sharp have puzzled mission scientists since before Curiosity's November 2011 launch. But the rover's recent observations at and near the mountain's base have brought the picture into much clearer focus, researchers said.At multiple locations, Curiosity noticed beds of sandstone sloping toward Mount Sharp. On Earth, such "inclined beds" are seen at deltas where rivers once emptied into lakes, said Curiosity science team member Sanjeev Gupta of Imperial College London. And that's likely what created the features on Mars, he added."These are likely to be quite small, maybe a couple of meters water depth — so very, very small deltas, but certainly clear evidence that we're building out, likely, into a standing body of water," Gupta said.The deposits were observed at multiple elevations, suggesting that they were laid down in multiple cycles, he added.Curiosity also spotted rocks with rhythmic, millimeter-scale banding at an outcrop at Mount Sharp's base called Pahrump Hills — something the robot had not seen before on Mars. Here on Earth, such finely banded rocks form when sediment rains down softly, so they're strong evidence for standing water, said Curiosity project scientist John Grotzinger, of the California Institute of Technology in Pasadena.Also at Pahrump Hills, Curiosity saw crystals in a rock that appear to be salts left behind after the evaporation of water, Grotzinger added."We don't imagine that this environment was just a single lake that stood for millions of years, but rather a system of alluvial fans, deltas and lakes and dry deserts that alternated for millions, if not tens of millions, of years as a connected system," Grotzinger said.The lake, when it existed, was probably not particularly deep, Gupta said. (While depths at the delta locations are just a few meters or so, it's difficult to estimate the depth of the overall lake.)Further, the southward inclination of the deposits is tough to explain if Mount Sharp had been present when they were laid down, reseachers said: Water should have flowed downhill, to the north, off Mount Sharp in these locations."The resolution of the paradox is to acknowledge that the layers represent a time when water was flowing from the crater rim toward the crater interior, and it filled up a series of stacks, and then subsequently those stacks of layers were eroded" to form Mount Sharp, Grotzinger said.So, sediment suspended in runoff water probably filled in much of Gale Crater over thousands or millions of years. Wind then carved away much of this material, leaving behind the enormous mound known as Mount Sharp, researchers said.A warmer, wetter MarsMars must have been a very different place about 3.5 billion years ago than it is today to support the Gale Crater lake, said Curiosity deputy project scientist Ashwin Vasavada, of NASA's Jet Propulsion Laboratory in Pasadena: It had to have been warmer, wetter and with a much thicker atmosphere.But climate models have a hard time explaining how such conditions could have persisted for long stretches on ancient Mars, Vasavada said. So perhaps a rethink is required."Maybe what we see can be explained as a result of shorter-lived warm and wet climates, created either by volcanism, orbital changes [or] large asteorid impacts, all of which were active at the time Mount Sharp was forming," Vasavada said. "Each event may have created warm and wet conditions for hundreds or maybe thousands of years, perhaps enough to fill Gale Crater with one more layer of sediment."The Curiosity rover reached Mount Sharp's base in September of this year after a 14-month trek. The rover spent its first year on Mars near its landing site, where it found strong evidence for an ancient lake-and-stream system that could possibly have supported microbial life long ago. The latest results strengthen and extend those original conclusions.Mars apparently had massive lake, NASA's Curiosity rover findsAmina Khan – Los Angeles TimesThe surface of ancient Mars may have been dotted by vast lakes that lasted long enough to give microbial life a chance to emerge on the Red Planet, NASA scientists said Monday.Geological evidence discovered by NASA's Curiosity rover suggests that a lake could have spanned the 96-mile-wide Gale Crater for perhaps millions of years. If so, that would contradict the idea that liquid water made only transient appearances on the Martian surface.These findings are based on an analysis of rocks at the base of Mt. Sharp, a 3-mile-high mound in the middle of the crater. Shapes and patterns in the rock point to a lake that filled and drained over tens of millions of years, according to scientists at the Jet Propulsion Laboratory in La Cañada Flintridge.In fact, the sediments deposited in this lake by snowmelt running down from the crater's rim could be what helped form Mt. Sharp in the first place."The puzzle pieces are coming together," said Michael Meyer, lead scientist for NASA's Mars Exploration Program.The Curiosity scientists examined rocks that seem to have formed at strange slanting angles. On Earth, this kind of buildup occurs when fast-moving river water suddenly hits a lake and has to decelerate.Curiosity's Mast Camera spotted these deposits at many different elevations along Mt. Sharp. This is a sign that the water cycle on Mars was active enough to produce steady amounts of runoff several times in Gale Crater's history, said Curiosity participating scientist Sanjeev Gupta of Imperial College in London.The delta-like deposits, with their characteristic slants, are in some ways even more telling than the finely layered sedimentary rock that most likely indicates a lake bed, said Curiosity project scientist John Grotzinger."This was a complete surprise," said Grotzinger, a Caltech geologist. "There was no way to have recognized this from orbit."Scientists don't believe there's much water left on Mars today, but that wasn't always the case."Mars was once a planet shaped by water," said JPL's Ashwin Vasavada, deputy project scientist for the Curiosity mission.Even in the past, the thinking goes, much of the planet's water was locked up in ice or held underground. But if there were large liquid lakes on the surface, then Mars must have had a thick atmosphere capable of preventing that water from escaping into space."The climate system must have been loaded with water," Vasavada said. "To sustain a lake at Gale Crater for millions of years, Mars would need a vigorous hydrological cycle to keep the atmosphere humid."The problem is, it's very difficult to generate a realistic model of the Martian atmosphere that explains how it could have been warm enough, not just thick enough, for these conditions to arise, Vasavada said.Some of those atmospheric mysteries may yet be addressed by NASA's MAVEN mission, which is studying what's left of the Martian upper atmosphere to gain insight into the Red Planet's past.Curiosity, known formally as the Mars Science Laboratory, is in its third year of exploration on the Red Planet. The $2.5-billion laboratory on wheels has already drilled up rocks in a spot called Yellowknife Bay that revealed signs of a past, water-rich, life-friendly environment on Mars.The sedimentary layers at the base of Mt. Sharp could hold the key to whether Mars was a much more habitable planet than it appears today.Looking to Mars to Help Understand Changing ClimatesDennis Overbye – The New York TimesTen thousand times a hundred thousand dusty years agoWhere now it stands the Plain of Gold did once my river flow.It stroked the stones and spoke in tongues and splashed against my face,Till ages rolled, the sun shone cold on this unholy place.That was the planet Mars as channeled by the folk singer and science writer Jonathan Eberhart in "Lament for a Red Planet."Ever since the Italian astronomer Giovanni Schiaparelli thought he spied lines that he called "canali" on Mars in 1877, earthlings' romantic thoughts about our nearest cosmic neighbor have revolved around water and its possible consequence, Life as We Know It. We haven't found life on Mars, but decades of robotic exploration have indeed strengthened astronomers' convictions that rivers and perhaps even oceans once flowed on the red planet.Today Mars is an arid, frigid desert, suggesting that the mother of all climate changes happened there, about four billion years ago or so. The question that haunts planetary scientists is why? And could it happen here?"I think the short story is the atmosphere went away and the oceans froze but are still there, locked up in subsurface ice," said Chris McKay, an astrobiologist and Mars expert at NASA's Ames Research Center.In September a new spacecraft known as Maven, the Mars Atmosphere and Volatile Evolution mission, swung into orbit around the planet. Its job is to get a longer answer to one part of the mysterious Martian climate change, namely where the planet's atmosphere went.One idea is that it was sputtered away by radiation and particles from the sun, known as the solar wind. Maven was designed to test that theory by measuring how fast Mars is losing atmosphere today. The results could help scientists determine what the atmosphere was like four billion years ago, and just how warm and wet the planet was."We're going to get some suggestive answers," said Bruce Jakosky, a University of Colorado professor and principal investigator for Maven.The results could resonate beyond Mars or even our solar system, shedding light on the fickle habitability of exoplanets. Alien astronomers looking at our solar system with a good telescope four billion years ago might have concluded that Mars was a likely habitat for life. Now look at it."What we are learning about are planetary atmospheres in general," said David Brain, a Colorado astronomer and Maven team member. "It's really fascinating to think that the planet changed in such a large way."Everybody agrees that Mars was once wetter, on the basis of two lines of evidence. The surface of the planet is crossed with features that resemble old river channels, like the tributaries and canyons that lead into Chryse Planitia, the Plain of Gold, an ancient crater 1,000 miles wide and a mile-and-a-half deep. And NASA's rovers have found minerals characteristic of watery environments, formed four billion years ago.But answers on exactly how wet and warm Mars was — and for how long — depend on whom you talk to.According to one camp, Mars back then had a thick atmosphere with enough carbon dioxide, the greenhouse gas looming big in Earth's future, to warm up the temperature and keep it there for the hundreds of millions of years it would have taken to carve the Martian river system. Others have suggested that phenomena like asteroid impacts or the tilting of Mars's poles could have produced shorter periods of near-freezing temperatures. The impact that created the huge crater called the Hellas basin, for example, would have hurled vast amounts of vaporized rock into the sky — leading to decades or centuries of hot rain and flash floods, said Brian Toon of the University of Colorado. It might have been followed perhaps by a lingering era of nearly freezing temperatures as clouds left over from the steam bath produced a mild greenhouse effect.Some geologists question whether the complicated river systems on Mars could have been created in such relatively short episodes, but they admit a serious flaw in their alternative view of a long-lasting greenhouse atmosphere of carbon dioxide. Namely, where did it go?"The holy grail of Mars," said Dr. Jakosky of the Maven team, is to find the carbonate deposits that should have formed from its atmosphere. "We haven't found them," he said.Which is where the new Maven mission comes in. One of the most striking clues that something has happened on Mars has come from atmospheric measurements from previous probes. They have shown that the lighter forms, or isotopes, of elements like hydrogen, nitrogen and argon are strangely depleted by contrast with their abundance on Earth.On Mars the ratio of heavy nitrogen, which has an extra neutron in its nucleus, to regular nitrogen is twice that of Earth. The same pattern goes for argon, which is Dr. Jakosky's favorite because it is chemically inert and can't disappear from the inventory except by being swept out of the atmosphere.All told, Dr. Jakosky said, the isotopic ratios on Mars suggest that about 60 to 90 percent of the atoms that were once in the Martian atmosphere might have been lost to space."We know the mechanism by which it was lost, but we can't quantify it yet," he said.The story goes something like this. Once upon a time, Mars had a magnetic field that, like Earth's, acted as an umbrella, deflecting the rain of energetic particles shed by the sun. Earth's field is generated by a dynamo, which in turn is powered by rising heat, convection in the planet's molten iron core. Once Mars cooled off, the dynamo and the magnetic field stopped and the solar wind began pecking away at Mars's atmosphere. Ultraviolet radiation from the sun would ionize atoms in the upper atmosphere, making them subject to forces from magnetic fields carried along in the solar wind, and they would slip away into space an atom or two at a time."A little bit every few hours," Dr. Brain of Colorado said, and "suddenly you can change an entire planet."Eventually — with no atmosphere, no rain and none of the tectonic churning that keeps Earth's oceans refreshed — the Martian rivers and oceans, if any, would have been absorbed into the ground and frozen, said James Kasting, a geoscientist at Penn State. Indeed, orbiting spectrometers have detected the signature of water in the form of ice under the wasted and lonely red sands.In September, after a 10-month trip from Earth and just in time to observe the effects of Comet Siding Spring pass by Mars, Maven began settling into a looping orbit around Mars, flying as close as 77 miles. Its instruments will observe the sun and solar wind; Mars's upper atmosphere, the pool from which escaping particles are drawn; and the particles themselves as they escape. By understanding how the atmosphere is reacting to the sun today, Dr. Jakosky said, scientists should be able to extrapolate and say how much of the Martian atmosphere has been removed to space over the eons.If the amount lost is substantial — "a couple of bars of CO2," he said, describing it in units of the atmospheric pressure on Earth — "would tell us that Mars must have been warmer in the past."If losses are trivial, he said, that would spell death for the early greenhouse theory, and the great Martian arguments would continue.ENDMore at www.spacetoday.net
No comments:
Post a Comment