Thursday, June 30, 2011

Update: Building a Coalition for Mars

In my last post, I talked about the challenges facing both ESA and NASA in building the political and budgetary framework for their joint Mars program.  This week, NASA's challenges are highlighted.  The U.S. agency was scheduled to deliver a letter of commitment to the program on June 28.  Uncertainties in the NASA budget outlook has meant that the U.S. cannot make that commitment now.  NASA hopes to be able to make that commitment by September 15 when it's budget outlook is clearer.

In the meantime, ESA has decided not to move forward on contracts for the 2016 orbiter and demonstration lander pending NASA's commitment.  ESA's managers are looking to work with their industrial partners to continue work on the most time critical elements of the 2016 mission to allow it to launch on time if the funding commitment comes through.

Additional Reading:

Space News: ESA Forced To Defer Full-scale Work on 2016 Mars Orbiter
BBC: Mars missions in summer slow lane 
AWST: NASA Funding Mired In Budget Politics

Editorial Thought:  I have great respect for the managers of NASA's Planetary Science program.  This budget uncertainty must be making what are already challenging jobs that much harder.  I wish them the best as they work through these issues.

Friday, June 24, 2011

Building a Coalition for a Mars Program

Space News has now published its third article this week on the problems that Europe is having creating a coalition behind the revamped Mars program.  To briefly recap, the European Space Agency (ESA) and NASA have agreed to combine budgets to enable joint 2016 orbiter and a 2018 rover missions.  (There will also be an ESA-only demonstration lander carried by the 2016 orbiter.)  The orbiter must fly before the rover to ensure that their is a satellite to relay the rover's data to Earth.  Budget pressures for both partners are requiring a major re-planning of the 2018 rover mission.

Originally France and now Britain (which are contributing 15% and 20%, respectively, of the costs for the European contribution to the missions) are asking for delays in proceeding with the 2016 mission until plans for the 2018 rover mission are firmed up.  The governments of these two nations reportedly are concerned that the overall program remains under funded and may seek to descope the 2016 mission to shore up funds for the 2018 mission.  Officials have raised concerns that the 2016 mission may experience cost overruns that would have to be met by taking funds from the 2018 mission.

Editorial Thoughts:  Planetary missions require years to scope, design, build, test, and then finally launch.  The plans for the 2016 mission have come together recently enough that it reportedly has a tight schedule.  Delays now to resolve the 2018 mission apparently could threaten the ability to launch in 2016.

From the Space News articles and other sources, it appears that building a coalition among the European nations and NASA faces three challenges:

Total available funds.  The 2016 orbiter and 2018 rover mission would be highly capable missions that are being combined with a budget (if I add figures together correctly) that is probably similar to the budget for the Mars Science Laboratory that will launch this year.  ESA's demonstration lander also requires funding from the ESA portion of this pot.  By reusing key pieces of NASA's Mars program technology such as the entry, descent, and landing system, there will be some key savings that will help reduce costs.

Merging goals: ESA and NASA came into this partnership with their own set of goals that need to be merged into flyable missions.  Here are the goals that originally came from each agency:

2016 mission
NASA - data relay, comprehensive measurements of trace gases in the atmosphere, continued high resolution surface imaging
ESA - data relay, demonstration lander

2018 mission
NASA - select, collect, and cache samples from the surface for future return to Earth
ESA - collect samples using a drill from below the surface and analyze them with a suite of highly capable instruments

Now that ESA and NASA have merged their Mars programs and agreed that the ultimate goal is a sample return, these goals have started to blur, and scientists on both sides of the Atlantic would like to see the full set of capabilities fly.  If budgets and schedules don't permit this, then the partners will have to find ways to agree on what to cut.

Internal politics: Both ESA and NASA get approval to start mission development and subsequent funding through political processes.  Both systems seem to have pluses and minuses.  ESA requires consent from its member nations that sometimes have conflicting goals based on their own scientific, technical, and industrial priorities.  Once an agreement is reached, future funding appears to be relatively stable.  NASA has a single government to respond to, but its budgets can fluctuate significantly from year to year as political moods at the White House and Congress change.  While ESA's political discussions are being highlighted now, NASA will effectively need to have its contribution to the program ratified through the inclusion of funding for it in next year's budget.  (The administration will propose the budget, but Congress can and probably will modify it.  Right now, budget politics within the U.S. are particularly volatile.)

Politics and planning can be messy, and we may see more articles like the Space News stories.  The nations within the partnership appear committed to a capable joint Mars program, so I expect that only the details that will be in doubt.  In posts next week, I'll provide more information on the current status of plans for these missions.


Follow these links to read the full Space News articles (listed in reverse chronological order):
France, Britain Reluctant To Recommit To Revised but ‘Risky’ ExoMars MissionDespite French Objections, ESA Seeks To Press Ahead on ExoMars French Concerns Throw ExoMars Plan Into Doubt

MSL: Cool Videos

JPL has just released a new, high-definition animation of NASA's Mars Science Laboratory (MSL) mission that "combines real scenes of Mars with spacecraft events such as landing on Mars and drilling into rocks."  Check it out at:

The journal Nature's news site has an article stating the science team's recommendation for MSL's landing site will be Gale Crater.  The article says that the expectation is that NASA headquarters is likely to ratify the selection.  If Gale is the selected landing site, a video produced by Doug Ellison shows what the terrain at Gale looks like.  The green lines are possible rover traverses.  The video is at

Wednesday, June 22, 2011

Latest Evidence for Enceladus Ocean

A new paper in the journal Nature reports new evidence for an ocean within Enceladus.  You can read a press release on the paper from NASA.

Monday, June 20, 2011

Enceladus Mission Options

Enceladus' plumes.  Credit Cassini Imaging TeamSSIJPLESANASA

Enceladus is back in the news following a science conference dedicated to the latest results hosted by the Enceladus Focus Group at the end of last month.  The journals Nature and Science (subscription or library access required) summarized latest findings presented at the conference.  

Two results of the conference stand out: First, the evidence is mounting that Enceladus contains a liquid ocean beneath at least a portion of its icy crust, and second, that that ocean is in contact with the moon's rocky core.  The combination of liquid water and minerals from rocks could provide the ingredients that are believed to be needed to enable the formation of life.  

While the evidence is mounting (Science quotes scientists as believing the likelihood of a liquid ocean is, " 'pretty likely,' 'most likely,' or 'almost inescapable,'), it is still circumstantial in part because the Cassini spacecraft's instruments are not ideally suited to studying the composition of the plumes.  After all, no one expected in the 1990s when the mission was designed to find a moon ejecting plumes of its interior into space.  A return mission is needed to confirm these interpretations of Cassini's data and to examine whether the building blocks for life may have formed.

Several Enceladus mission concepts were considered by the Decadal Survey, and one was a runner up recommended for flight if more money than then planned became available for developing planetary missions.  We now find ourselves in the opposite situation where less money than expected was planned.  The $1.9 billion Enceladus orbiter described in the Survey's report now seems unlikely.  

At the Focus Group's meeting, Nathan Strange, a mission architect at JPL, presented a history of investigations into Enceladus missions and options for a new mission to this moon.  Since the discovery of the plumes, a number of teams have looked into follow-on missions:

2006 GSFC NASA Academy EAGLE Study
2006 NASA “Billion Dollar Box” Study
2007 NASA Enceladus Flagship Study
2007 ESA Titan and Enceladus Mission (TandEM)
2007 JPL Enceladus RMA Study
2008 NASA/ESA Titan Saturn System Mission (TSSM)
2010 PSDS Decadal Survey Enceladus Studies
2010 JPL “JET” Discovery Proposal (PI: Christophe Sotin)

The 2006 Billion Dollar Box study (goal: find compelling Enceladus or Titan missions at or less than $1B, it didn’t find any) and the Decadal Survey looked at the greatest number of options.  One set of missions identified would have a spacecraft orbit Saturn and perform multiple flybys of Enceladus:

  • Multi-flyby missions where the spacecraft's orbit crosses the orbits of Titan and Enceladus, resulting in 10-20 encounters with both moons.  At Enceladus, the encounters occur at the relatively high speed of 4 kilometers per second.  (The Cassini spacecraft uses orbits of this type for its Enceladus encounters as would the proposed JET mission.)  These are the cheapest missions, estimated in the neighborhood of $1.5B by both the Billion Dollar Box and Decadal Survey studies.
  • Early flybys of Titan followed by a leveraging tour in which many (20-50 of each moon) low-speed flybys of Rhea, Dione, and Tethys for gravity assists enable 50 or more Enceladus flybys per year at speeds ~1 km/s.  These missions incur greater mission operations costs from both the longer mission time and the larger staff needed to manage the many encounters.
  • Plume sample returns in which icy particles are captured during plume and E-ring (composed of material from the plumes) flybys in a manner similar to the Stardust comet sample returns.  These missions require technology to capture and preserve volatile material and to prevent release of the returned samples into Earth’s biosphere even in the event of a crash landing of the return vehicle.  The authors of Decadal Survey report found these issues to be significant impediments to flying this mission.

At the next level of complexity are Enceladus orbiters.  These missions would use the leveraging tour to lower the spacecraft's Saturn orbit to allow orbital insertion at Enceladus.  Orbital missions incur the cost of the longer, more complex tour with the cost of larger fuel tanks for the insertion burn.  Because Enceladus is a tiny gravity well deep in Saturn's much deeper gravity well, polar orbits would be unstable.  As a result, polar orbits would be unstable, making the study of the plumes, which are found at the south pole, difficult.  The plumes would either have to be studied in the low speed flybys prior to insertion or from brief excursions from stable orbits around Enceladus.  An orbiter would allow detailed studies of the surface and interior of Enceladus up to latitudes of ~65 degrees, providing the opportunity to study the extent of any interior oceans and study the surface history of this moon.  The Decadal Survey studies concluded that a simple orbiter would cost ~$1.9 billion, or about half again (with launch costs included) the costs of a New Frontiers mission.

Beyond these simpler missions would be an entire range of missions that include landers (hard to plan for with our current knowledge of the surface properties) and even missions in which the spacecraft would orbit both Titan and Enceladus.

Nathan Strange concluded his presentation with a list of the mission options that, in his opinion, might be possible to squeeze under the cost caps of the Discovery and New Frontiers programs:

Within the lower mission cost Discovery program:

  • Plume sample return
  • Titan-Enceladus flyby mission
  • Icy-moon leveraging tour (many moon flybys resulting in low speed Enceladus flybys)

Within the medium mission cost New Frontiers program:

  • Enceladus orbiter or orbilander (a spacecraft that first orbits and then lands on Enceladus)
  • Icy-moon leveraging tour
  • Plume sample return
  • Enceladus impactors

Strange emphasizes that these are ideas to explore and that these are concepts that might be "feasible with innovation and creativity."  However, "Currently, there is no obvious solution for a low-cost mission above the science floor [minimum requirements]. We must innovate to both lower the cost and increase the science value of concepts."

Editorial Thoughts: If you are a regular reader of this blog, you've probably noticed that I've spent quite a bit of time exploring options, post Decadal Survey and lower projected budgets, relating ideas for continuing exploration of the icy-ocean moons.  I believe that exploration of these moons should be a priority in the next decade if the science community and mission architects can develop feasible concepts.  I wish Strange and his colleagues the best of luck in finding missions that thread that intersection between costs, feasibility, and compelling science that will enable one or more of these missions to launch in the next decade.

Additional Resources:

Nathan Strange’s presentation to a Decadal Survey meeting 

The end of Nathan’s presentation has references for additional reading 

Two Decadal Survey Enceladus mission concept study reports can be found here

NASA Enceladus Flagship Study Report, NASA Goddard Space Flight Center, 2007

Titan Saturn System Mission Final Report on the NASA Contribution to a Joint Mission with ESA, Jet Propulsion Laboratory, 2009.

Thursday, June 16, 2011

A Preview of What OSIRIS-REx May Return

Origin and Evolution of Prebiotic Organic Matter As Inferred from the Tagish Lake Meteorite Christopher D. K. Herd, et al. Science 332, 1304 (2011); DOI: 10.1126/science.1203290

Chance has provided us with a preview of the types of scientific analysis the samples returned by the just approved OSIRIS-REx asteroid sample return mission may provide.  In early 2000, a fragment from a primitive asteroid entered the Earth's atmosphere.  It is rare for scientists to be able to examine fairly pristine samples of these asteroids.    In this case, the fragments landed on the frozen Tagish Lake in the Yukon region of Canada.  A local resident spotted the samples lying on the ice, carefully retrieved them, and kept them frozen until they could be delivered to scientists.  (Scientists also later retrieved additional samples in the spring before the ice had thawed.)   (See for more on this meteorite.)

Last week, a paper in the journal Science published the latest findings from this meteorite (see the press release below).  The opening of the paper explains why carbonaceous chondrite samples -- the type of material in the Tagish Lake meteorite -- are so important to scientists wanting to understand the early solar system: these samples come from primitive asteroids that preserve the materials of the early solar nebula and results of the processes that occurred within those early building blocks.

The conditions for finding carbonaceous condrite meteorites in pristine condition are rare.  Instead of waiting for a random sample to come to us, the OSIRIS-REx asteroid sample return mission will go to the asteroid to carefully select its samples to return to Earth.  

Dante Lauretta, Deputy PI for the mission, has been kind enough to send me material on the mission over the past two years that have formed the basis for posts on this mission in this blog.  I asked him if the the Tagish Lake samples are representative of the type of material they hope to return and whether baking by the sun might degrade the sample.  He wrote back, "Tagish Lake is a good analog for the type of material that we are interested in. Our spectral analysis of 1999 RQ36 suggests it is most similar to the CM1 chondrites. 

"We are interested in the interaction of the organic material with solar radiation. Organic does not always mean volatile and it is likely that even a heavily space weathered surface would have interesting organic chemistry. One of our objectives is to understand the effect of this 'space weathering' on carbonaceous material. However, we have evidence that the surfaces of near-Earth objects may be refreshed during exceptionally close planetary encounters. Tidal forces are strong enough to turn small bodies inside out, especially if they are rubble piles. This is good news for us since 1999 RQ36 is likely to have had multiple close encounters with the Earth in its recent history. If these theories are correct, NEOs with Earth close approaches may be ideal material to sample relatively fresh, low-space-weathering material right on the surface. These are some of the hypotheses that our mission will be testing."

The following press release from NASA's Goddard Space Flight Center gives more background on the Tagish Lake meteorite has reveal and possibly previews the kinds of discoveries to be enabled by the OSIRIS-REx samples.

Some asteroids may have been like "molecular factories" cranking out life's ingredients and shipping them to Earth via meteorite impacts, according to scientists who've made discoveries of molecules essential for life in material from certain kinds of asteroids and comets. Now it appears that at least one may have been less like a rigid assembly line and more like a flexible diner that doesn't mind making changes to the menu. 

In January, 2000, a large meteoroid exploded in the atmosphere over northern British Columbia, Canada, and rained fragments across the frozen surface of Tagish Lake. Because many people witnessed the fireball, pieces were collected within days and kept preserved in their frozen state. This ensured that there was very little contamination from terrestrial life. 

A fragment from the Tagish Lake meteorite fallThis is one of the Tagish Lake meteorite fragments. Credit: Michael Holly, Creative Services, University of Alberta.
Full-resolution copy 
"The Tagish Lake meteorite fell on a frozen lake in the middle of winter and was collected in a way to make it the best preserved meteorite in the world," said Dr. Christopher Herd of the University of Alberta, Edmonton, Canada, lead author of a paper about the analysis of the meteorite fragments published June 10 in the journal Science. 

"The first Tagish Lake samples -- the ones we used in our study that were collected within days of the fall -- are the closest we have to an asteroid sample return mission in terms of cleanliness," adds Dr. Michael Callahan of NASA's Goddard Space Flight Center in Greenbelt, Md., a co-author on the paper. 

The Tagish Lake meteorites are rich in carbon and, like other meteorites of this type, the team discovered the fragments contained an assortment of organic matter including amino acids, which are the building blocks of proteins. Proteins are used by life to build structures like hair and nails, and to speed up or regulate chemical reactions. What's new is that the team found different pieces had greatly differing amounts of amino acids. 

"We see that some pieces have 10 to 100 times the amount of specific amino acids than other pieces," said Dr. Daniel Glavin of NASA Goddard, also a co-author on the Science paper. "We've never seen this kind of variability from a single parent asteroid before. Only one other meteorite fall, called Almahata Sitta, matches Tagish Lake in terms of diversity, but it came from an asteroid that appears to be a mash-up of many different asteroids." 

By identifying the different minerals present in each fragment, the team was able to see how much each had been altered by water. They found that various fragments had been exposed to different amounts of water, and suggest that water alteration may account for the diversity in amino acid production. 

"Our research provides new insights into the role that water plays in the modification of pre-biotic molecules on asteroids," said Herd. "Our results provide perhaps the first clear evidence that water percolating through the asteroid parent body caused some molecules to be formed and others destroyed. The Tagish Lake meteorite provides a unique window into what was happening to organic molecules on asteroids four-and-a-half billion years ago, and the pre-biotic chemistry involved." 

If the variability in Tagish Lake turns out to be common, it shows researchers have to be careful in deciding whether meteorites delivered enough bio-molecules to help jump-start life, according to the team. 

"Biochemical reactions are concentration dependent," says Callahan. "If you're below the limit, you're toast, but if you're above it, you're OK. One meteorite might have levels below the limit, but the diversity in Tagish Lake shows that collecting just one fragment might not be enough to get the whole story." 

Although the meteorites were the most pristine ever recovered, there is still some chance of contamination though contact with the air and surface. However, in one fragment, the amino acid abundances were high enough to show they were made in space by analyzing their isotopes. 

Isotopes are versions of an element with different masses; for example, carbon 13 is a heavier, and less common, variety of carbon. Since the chemistry of life prefers lighter isotopes, amino acids enriched in the heavier carbon 13 were likely created in space. 

"We found that the amino acids in a fragment of Tagish Lake were enriched in carbon 13, indicating they were probably created by non-biological processes in the parent asteroid," said Dr. Jamie Elsila of NASA Goddard, a co-author on the paper who performed the isotopic analysis. 

The team consulted researchers at the Goddard Astrobiology Analytical Lab for their expertise with the difficult analysis. "We specialize in extraterrestrial amino acid and organic matter analysis," said Dr. Jason Dworkin, a co-author on the paper who leads the Goddard laboratory. "We have top-flight, extremely sensitive equipment and the meticulous techniques necessary to make such precise measurements. We plan to refine our techniques with additional challenging assignments so we can apply them to the OSIRIS-REx asteroid sample return mission." 

OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security -- Regolith Explorer) is a Goddard-managed mission, led by the University of Arizona, that will be launched toward asteroid "1999 RQ36" in 2016 and return a sample to Earth in 2023. The OSIRIS-REx team is led by Dr. Michael Drake, Director of the University of Arizona's Lunar and Planetary Laboratory. 

The Tagish Lake research was funded by the Natural Sciences and Engineering Research Council of Canada, the Alberta Ingenuity Fund, and NASA. 

Tuesday, June 14, 2011

Goals of ESA's Mars Demonstration Lander

In the previous post, I reported on the instruments planned for ESA's 2016 demonstration Mars lander.  Questions have been asked as to why this lander will be purely battery powered with a life on the surface of a day or two.  I wrote to Giacinto Gianfiglio, ExoMars System Engineering Manager, and asked him why solar panels allowing longer life had not been included.  He replied,

"In a larger Lander configuration indeed there were deployable solar array panels foreseen, but this solution would have implied:

-     soft landing with air bags (that we have now discarded for volume-mass-cost reasons)
-     deployable panels of the landed structures (that we have now discarded for volume-mass-cost reasons)

We have also changed the mission objectives from a relatively long life lander (one to two months) to a "demo" lander of only about two days of surface life time ... this enables to survive with just batteries .... and gain all this is to save volume-mass-cost."

This lander is part of a larger effort by ESA to develop technologies to explore Mars that also includes development of the capabilities needed to design and operate a rover on Mars.  ESA's website states:

"The task of MREP [Mars Robotic Exploration Preparation Programme] is to define and prepare for the next steps that Europe will take after these [the 2016 mission]... ESA has a distinguished history of space science missions, but the demands of Mars Sample Return (MSR) mission mean moving the Agency far out of its technological comfort zone. ESA does not currently have expertise in precision soft-landing probes and operating them on planetary surfaces, identifying and retrieving samples and then – as is a requirement for MSR – having them take off again to dock remotely in Mars orbit. Then there is the difficulty of preserving the samples in pristine condition and getting them safely through re-entry back to the surface of the Earth... MREP sets up a framework for more systematic and structured international cooperation with the United States and other exploration partners in the decades to come, enabling an increased number of missions than either partner could achieve alone. The target is to have Europe present on each mission slot to Mars - which is every two years - as mission leader or important contributor."

Editorial Thoughts: Why create program focused technology development? The U.S. Decadal Survey report had this to say about the importance of technology development in enabling planetary missions: "Continued success of the NASA planetary exploration program depends upon two major elements. It is axiomatic that the sequence of flight projects must be carefully selected so that the highest priority questions in solar system science are addressed. But it is equally important that there be an ongoing, robust, stable technology development program that is aimed at the missions of the future, especially those missions that have great potential for discovery and are not within existing technology capabilities. Early investment in key technologies reduces the cost risk of complex projects, allowing them to be initiated with reduced uncertainty regarding their eventual total costs." 

The Decadal Survey report included two examples of how focused technology development programs enabled subsequent planetary missions. The Solar electric propulsion (SEP) had been proposed for many solar system exploration missions, but none of those proposals had been implemented.  In 1998, NASA launched the Deep Space One mission to demonstrate the use of SEP and a number of other technologies.  While the spacecraft carried out limited science goals during encounters with the asteroid Braille and the comet comet Borrelly, the focus was on technology development and gaining experience operating a SEP spacecraft.  The demonstration of this technology led to NASA accepting the use of SEP in the Discovery Dawn mission to the large asteroids Vesta and Ceres.  (And allowing us to enjoy the in depth mission updates of JPL's Marc Rayman, who has participated in both missions.)  The second example was the development and operation (on Earth) of a series of rovers and the Mars Pathfinder landing system that enabled the Mars Spirit and Opportunity missions at Mars.

Today's ExoMars program is part of a joint ESA-NASA Mars exploration program that allows the two agencies to share costs.  As a result, the ExoMars program has had to be significantly modified and delayed to match NASA's technical and budget requirements.  Through the replans, ESA has continued its focus of using the ExoMars program to develop its technical capabilities so that it can be an equal player in the joint Mars program with NASA.  The decision to fly a demonstration lander with a focus on technology development with minimum science goals appears to come from that continued focus.

There has been a lively debate at the Unmanned Spaceflight forum as to whether this demonstration lander is a good investment for ESA.  I generally don't care to comment on political issues (and where to allocate investments is a political decision; my opinion is no more valid than those of my readers).  I will point out that right now the future of landed missions on Mars is subject to the whims of the U.S. political system as only NASA possesses developed Mars entry and landing technology.  Having a second space agency invest in these capabilities does not seem unreasonable.  What kinds of missions might make use of this technology?  If the joint NASA-ESA sample return program doesn't move forward (and likely won't past 2018 without a higher projected planetary budget for NASA), ESA could use this technology for post 2018 rovers, polar landers, or geophysical stations.  Once the technology is developed, it will be much easier to approve missions that use it, just as it was to approve the Dawn and Mars Exploration Rover missions once their underlying technologies were proven entities.

Saturday, June 11, 2011

Instruments for ESA's Mars Landing Demonstrator

The European Space Agency posted the press release below on its website.  The science goals are quite limited -- this is a technical demonstration project and the lander will function for just two to four days on the surface.  The landing site is Meridiani Planum, for which we already have many images from the Opportunity Mars rover.  You can read about the goals and technology of the demonstrator at  

Entry, descent and surface science for 2016 Mars mission
10 June 2011
ESA and NASA have announced the scientific investigations selected for their 2016 ExoMars lander demonstrator. They will probe the atmosphere during the descent, and return the first ever data on electrical fields at the surface of Mars.

The demonstration lander on the surface.   Click on image to see full illustration of the landing process.  Credit: ESA

The EDM Entry, descent, and landing Demonstrator Module is part of the joint ESA/NASA ExoMars Trace Gas Orbiter mission to be launched in 2016 for arrival at Mars nine months later.

Although its main goal is to demonstrate European entry, descent and landing technologies for future visits to Mars, it will also offer some limited, but useful, scientific opportunities.
“The EDM will be landing during the dust storm season,” says Jorge Vago, ExoMars Project Scientist. “This will provide a unique chance to characterise a dust-loaded atmosphere during entry and descent, and to conduct interesting surface measurements associated with a dust-rich environment.”  

“Although its main goal is to demonstrate European entry, descent and landing technologies for future visits to Mars, it will also offer some limited, but useful, scientific opportunities.”
For the descent phase, two proposed investigations called Entry, Descent and Landing (EDL) Science and IDEAS (Investigations During Entry and Atmospheric Science) were selected and combined into one Entry and Descent Science programme.
The joint team will use the module’s entry, descent and landing engineering data to reconstruct its trajectory and determine the atmospheric conditions.
Once on the surface, the DREAMS (Dust characterisation, Risk assessment, and Environment Analyser on the Martian Surface) scientific payload will function as an environmental station for the two to four days of the surface mission.

The ExoMars Trace Gas Orbiter
To achieve this, teams of scientists and engineers from nine countries around the world will develop a dedicated suite of sensors to measure the wind speed and direction (MetWind), humidity (MetHumi), pressure (MetBaro) and surface temperature (MarsTem), and to determine the transparency of the atmosphere (ODS).
DREAMS will also make the first measurements of electrical fields at the planet’s surface with its MicroARES detector. Electrical fields are likely to be generated when grains rub against each other in the dust-rich atmosphere, so landing during the dust storm season increases the chance of being able to study this charging and its consequences.
In addition to the surface payload, a colour camera system on the EDM will deliver valuable additional scientific data, as well as spectacular images. No design has yet been chosen for the camera, but a decision is expected before the end of this year.
“The selection of these science investigations complements the technological goals of the EDM,” says Dr Vago. “This has been an important step that will allow our team to move on to the development of this important mission element.”

Wednesday, June 8, 2011

This is rocket science

Because NASA's planetary missions on the whole have been so incredibly successful, many of us outside the process can forget how incredibly complicated it can be.  A just released audit (see post on the journal Nature's blogSpace News, and Space Ref) gives examples of the issues still to be addressed on the Mars Science Laboratory as it prepares to launch.  From what I've read, this seems normal at this stage (read Steven Squyres' book on the Mars Exploration Rovers for more examples of pre-launch issues).

I once had lunch with a planetary scientist who began his career in the 1950s.  He told me that in the late 1950s, he came to believe we would never send probes to other planets because statisticians had shown that you could never achieve the reliability necessary for the missions to succeed.  Of course, the various space agencies proved him wrong (often with dramatic failures that served as learning opportunities).  When I think of the great advances brought by the space age, I am less impressed by the technical wonders and more impressed by the management systems that can deal with these levels of complexity, especially for missions such as MSL that expand the technical capabilities on so many fronts.  This audit is part of the management system, in this case providing an outside review of issues.

Tuesday, June 7, 2011

Enabling the 2018 ESA-NASA Mars Rover

Aviation Week and Space Technology has an article on the on-going challenges of combining the ESA and NASA rovers into a single rover for the 2018 mission.  It doesn't sound as if there are fundamental problems, but rather the proverbial problem of trying to fit a lot of capability into a fixed (and smaller budget).

We may get more detail at the international Mars Exploration Analysis Group (MEPAG) meeting next week.

Monday, June 6, 2011

OSIRIS-REx: More than a Sample Return Mission

The Martian moon Phobos, which may be a captured asteroid.  This image shows the complexity of the surfaces of small, primitive bodies.  Phobos, with a mean diameter of 11.1 km is many times larger than the OSIRIS-REx target, asteroid 1999 RQ36.  Credit: HiRISEMROLPL (U. Arizona)NASA

"The Near-Earth Asteroid Rendevous (NEAR) mission to 433 Eros demonstrated that even small asteroids are covered with complex and substantial regoliths, which are heterogeneous in texture and detailed in composition.  To understand the geologic evolution of asteroids, regoliths must be studied in detail, and their variability must be characterized both vertically and horizontally... To maximize the science return from such a mission, it is essential to select the most interesting locales on the asteroid, a goal that implies a global reconnaissance of the target body."
-- New Frontiers in the Solar System An Integrated Exploration Strategy [2003 Planetary Decadal Survey]

[An asteroid sample return mission] "should have the following science objectives...":
  • "Map the surface texture, spectral properties (e.g., color, albedo), and geochemistry of the surface of an asteroid at sufficient spatial resolution to resolve geologic features (e.g., craters, fractures, lithologic units) necessary to decipher the geologic history of the asteroid and provide context for returned samples.
  • "Document the regolith at the sampling site in situ with emphasis on, e.g., lateral and vertical textural, mineralogical, and geochemical heterogeneity at scales down to the submillimeter.
  • "Return a sample to Earth in an amount sufficient for molecular (or organic) and mineralogical analyses, including documentation of possible sources of contamination throughout the collection, return, and curation phases of the mission."
-- Opening New Frontiers in Space: Choices for the Next New Frontiers Announcement of Opportunity [2008]

The selection of the OSIRIS-REx New Frontiers mission to return a sample from a near-Earth asteroid has been widely reported.  As the quotes that open this post state, simply returning a sample of an asteroid is only part of a robust sample return mission.  It is also important to try to understand the history of the asteroid.  While OSIRIS-REx's target asteroid, 1999 RQ36, is believed to represent a primitive composition that will likely tell us much about conditions in the early, pre-planet solar system, the body has experienced over four billions years' worth of events.  This tiny body, 575 m in diameter, is likely a fragment of a larger asteroid.  Since its separation from its original parent body, this asteroid will have been pounded by numerous collisions and may well be a pile of rubble with materials from various depths of its parent body jumbled together and exposed on the surface.  That material on the surface from which the sample will be taken has been exposed for an unknown period of time to the baking and irradiation of the sun, which may have modified its composition.

All of these factors require that a robust sample return mission also be able to fully characterize the surface and interior of its target asteroid.  Earlier versions of this mission, then called only OSIRIS, focused only on the sample return.  The recently approved version of the mission includes a suite of instruments to remotely study this body:

  • Camera Suite (OCAMS) Provides long-range acquisition of 1999 RQ36, along with global mapping, sample-site characterization, sample acquisition documentation, and sub-mm imaging
  • Visible and IR Spectrometer (OVIRS) Provides mineral and organic spectral maps and local spectral information of candidate sample sites from 0.4 - 4.3 μm
  • Thermal Emission Spectrometer (OTES) Provides mineral and thermal emission spectral maps and local spectral information of candidate sample sites from 4 - 50 μm
  • X-ray Imaging Spectrometer (REXIS) instrument as a student collaboration experiment. This instrument will be built by MIT and Harvard students and is designed to map the abundances of major elements on the surface of the asteroid
  • Laser Altimeter (OLA) Provides ranging data; global topographic mapping; and local topographic maps of candidate sample sites
  • Spacecraft Telecom Radio science provides RQ36 mass and gravity field maps
OSIRIS-REx Spacecraft and Instruments

The suite of instruments are synergistic.  The cameras, for example, will document the physical structure of the surface, providing clues to past events.  The OVIRS and OTES instruments will measure different portions of the visible and infrared spectra to understand the composition of the surface minerals.  The REXIS instrument, by contrast, will look at the elemental composition of the surface.  (A simple analogy of the difference between elemental and mineralogical composition: Bread and cake have similar 'elemental' compositions based on flour, water, and sugar, but the combination of those elements result in distinct 'mineralogies'.)  The laser altimeter and radio science together will map the shape of the surface and distribution of mass inside RQ36, which together will provide clues to the interior structure.

The instruments on OSIRIS-REx will have dual purposes.  While they will help us understand the composition and history of this body, they will also help mission planners to plan the sample acquisition.  The cameras and laser altimeter will reveal the physical geography of potential sample sites, while the spectrometers will reveal the composition.  (My guess: Mission controllers will select a site that has the best mixture of materials on the surface to sample the greatest heterogeneity.)

The OSIRIS-REx spacecraft will spend more than a year studying 1999 RQ36.  By the end of this period, it will probably be, square-meter-for-square-meter,  the most intensively studied body in the solar system.

OSIRIS-REx is not the only mission that aims to return a sample of a likely primitive small body.  Russia's Phobos-Grunt mission will leave this year on a round trip to the Martian moon Phobos, which may be a captured asteroid.  (RQ36 is a B-type asteroid, while Phobos is a likely C-type body, which are both believed to represent relatively unaltered samples of the non-volatile early solar system.)  Russia's mission will carry a number instruments to characterize its target moon.  In fact, it's instrument suite is more wide ranging than OSIRIS-REx's, with both remote sensing and surface instruments.  

OSIRIS-REx and Phobos-Grunt will be joined this decade by the Hayabusa 2 mission, which will also sample a primitive, C-type asteroid.  It appears that Hayabusa 2 will, like Hayabusa 1, carry a number of remote sensing instruments to characterize its target and plan for the sample acquisition.  The European Space Agency is also considering a primitive asteroid sample return mission, Marco Polo-R, for the 2020s that will likely carry several remote sensing instruments. 

The OSIRIS-REx mission will also carry a sampling mechanism.


The OSIRIS-REx team has posted a fact sheet on the mission:  All images in this post, except the image of Phobos, are from the fact sheet and are reused with permission.

Several articles in Wikipedia provide background on the types of asteroids:

B-type asteroids (which are considered a sub-type of C-type asteroids):