Friday, July 18, 2014

Mars and Europa: Contrasts in Mission Planning

The big news for future planetary exploration this month is likely to be the announcement of the instrument selection for NASA’s 2020 Mars rover that will define how it will fulfill its scientific goals.  In the meantime, there have been several announcements for proposed missions to Mars and on the planning for a NASA return to Europa that highlight the contrasts in planning missions for these two high priority destinations. 

China’s chief scientist for its lunar program has stated that China is planning a rover mission to Mars for 2020 and a sample return from that planet by 2030.  The Chinese space program tends to be tight lipped about its plans (especially those still several years out), and I’ve been unable to find any more information.  Is this mission a placeholder on the space agency’s roadmap – much like an eventual Martian sample return for NASA – or an approved and funded program?  Would the rover be delivered by a small lander and therefore be small itself, perhaps like NASA’s 1996 Sojourner rover?  Or perhaps it would be a medium sized rover like China’s Yutu lunar rover and NASA’s Opportunity rover.  Given China’s string of successes and careful build up to more complex missions, if a Martian rover is firmly in their plans, they seem likely to succeed. 

A Chinese rover would find itself part of a crowd on the Martian surface in 2020.  As mentioned above, NASA plans its own Curiosity-class rover for that year.  Europe’s ExoMars rover is likely to still be operating along with its Russian stationary lander.  I’m willing to bet that NASA’s 2016 InSight lander and Curiosity rover will still be functioning, and I have some hope that the Energizer bunny-Opportunity rover will still be alive (although perhaps as a stationary platform by then).

Mars exploration has reached the point where private organizations can promote credible plans for complex Mars missions on the web.  Credit: BodlyGo Institute and Mars One

If two private organizations have their way, the party at Mars will be more raucous still.  The BoldlyGo Institute would like to raise funds for its SCIM spacecraft that would dip briefly into the upper atmosphere during a high speed flyby to snag dust and atmosphere samples to return to Earth.  While we have some 130 rocks delivered as meteorites that are believed to be from Mars, this mission would return samples of the dust that ubiquitously blankets the planet.  If this idea seems familiar, it was proposed twice before in NASA’s Mars Scout and Discovery mission competitions.  Now its backers hope that this mission will have better success at securing private funders.

Another organization, Mars One has been planning to land humans on Mars in about a decade’s time.  Recently, it announced plans for a Martian lander for 2018 built on the same platform as NASA’s Phoenix and InSight landers.  Mars One is seeking proposals for instruments that would be useful to eventually colonization of Mars.  For example, the organization is requesting proposals to demonstrate water extraction from the soil.  It would also deliver one instrument developed by a university to the surface of Mars.

Both of these missions depend on finding funding from some combination of rich donors, corporate sponsors, and crowd sourcing from small donors. I’m never quite certain how much hope to hold out for missions that depend on private donations.  Given their scope, these two missions would likely costs of several hundred million dollars; each mission would either need a fantastic number of small contributors or one or more wealthy contributors.  While rich space enthusiasts exist (I’m thinking of  Elon Musk of SpaceX as an example), if you are very, very rich and have the slightest inkling towards philanthropy, then fund raisers from many worthy causes from universities to global health to saving species are already in touch with you. 

Rather than dividing potential support, having multiple organizations trying to raise funds may benefit private planetary exploration.  We can’t know beforehand which, if any, approaches will open check books and competition may help us learn what will work.  (The B612 Foundation is another player looking to finance a challenging mission, in their case a space telescope to search for near Earth asteroids.)

Jeff Foust at The Space Review had a story recently on the potential for private funding of space missions.   While raising hundreds of millions of dollars my prove too daunting, technology is on the cusp of enabling small planetary spacecraft based on CubeSat and SmallSat technologies that would cost just a few tens of millions of dollars.  The Planetary Society’s LightSail project is an example of such a mission (although it will test critical hardware in Earth orbit rather than fly to another world).

If planning for Mars missions is becoming commonplace, NASA is still trying to find a plan to for a dedicated mission to Europa.  In a step forward, the agency has released a request for proposals to the scientific community for instruments for a Europa mission.  It did so, however, in a rather odd fashion.

Reddish features in this colorized image of Europa's surface likely contain  water ice mixed with hydrated salts, potentially magnesium sulfate or sulfuric acid that may represent material from the interior ocean.  Full caption available at Credit: NASA/JPL-Caltech/SETI Institute

Usually when NASA requests instrument proposals, it has a solid mission concept in mind.   For this call, NASA said that the Europa mission might be an orbiter or might be a multi-flyby spacecraft.  The request document was vague as to the budget for instruments and just said that past studies assumed it would likely be around 15% of the total mission cost.  While many instruments by their nature have modest costs, some could be quite costly and it might help proposers to know whether the total instrument budget is closer to $150M (for the $1B total mission cost NASA would like) or to $300M (for the ~$2B that past studies have said is needed to achieve all the high priority scientific goals).

For some instruments, proposers will have to bet that NASA either selects a multi-flyby spacecraft or an orbiter.  For example, measuring Europan tides would help pin down the depth of the ice covering the ocean.  A laser altimeter could accurately measure the tides, but it requires an orbiting platform to pin down the size of the tides.  If NASA goes with a flyby spacecraft, any group that proposed an altimeter is likely to be out of luck.

Examples of instruments that the scientific community may propose to study Europa.  From the Europa instrument Announcement of Opportunity available here.

The request for proposals gives two roadmaps for how NASA will select the winning proposals.  Its managers expect that they will select up to 20 proposals in April 2015 for which they will fund further development towards a final selection of approximately eight instruments a year later.  NASA also reserves the right to simply select the final instrument suite in April 2015.  The document implies that the longer timeline assumes a launch no earlier than 2021, while the shorter timeline could either reflect a possible earlier launch date or the possibility that the proposals seem ready for selection without an additional year of maturation. 

With this request, NASA appears to be showing its commitment to an eventual Europa mission, but it still hopes to find a cheaper alternative that will win the allegiance of the scientific community.  The large cost overruns on the Curiosity Mars rover and James Webb Space Telescope have made the White House’s budget managers and NASA’s senior managers wary of multi-billion dollar missions. reports that NASA has received a number of concepts for Europa missions that might cost no more than $1B.  The agency is currently assessing these ideas for their cost, technical, and scientific feasibility.  Comments by NASA’s chief scientist suggest that these missions likely would perform only a fraction of the science considered high priority by the scientific community (and that would be accomplished by the current ~$2B mission concept).

In the request for instrument proposals, NASA specifically asked for instruments that could study possible plumes of water erupting from Europa.  The recent possible discovery of plumes at Europa has raised the question of whether and how planning to explore this world should be changed.  If the plumes are verified, then they represent a chance to directly study material being ejected into space from beneath Europa’s surface as Cassini has been able to do for Saturn’s moon Enceladus. 

The request comes despite the recommendations a few weeks earlier of NASA’s Europa Science Definition Team.  They reviewed both the evidence for Europan plumes and the experience studying plumes erupting from Saturn’s moon Enceladus with the Cassini spacecraft.  Their recommendation was that a mission to Europa should be capable of exploring plumes if they exist, but that a dedicated focus on the plumes would not be appropriate. 

First of all, the team noted, only one observation made by the Hubble Space Telescope saw possible plumes.  Other searches for plumes by telescopes and by the Galileo spacecraft when it orbited Jupiter have not found unambiguous evidence for plumes.  (Some Galileo data is consistent with plumes but also have other possible explanations.)  Even if the Hubble did observe one or more plumes, they may occur at sporadic intervals separated by years or decades.  If so, they would be more like the sporadic eruptions of each volcano on Io than the so-far continuous eruptions seen at Saturn’s Enceladus.  A mission to Europa lasting a few years might entirely miss plumes if they sporadically erupt.

Second, Cassini’s observations of Enceladus’ plumes have shown the power of a diverse instrument set to characterize plumes.  Instruments already recommended for the ~$2B Europa mission concept could be used to search for and study any plumes.  A mass spectrometer, for example, could determine the composition of the gases expelled from the surface, while the thermal imager could look for warm spots that would be the source of the plumes.  A couple of instruments such as a UV spectrometer and a dust spectrometer that haven’t made the straw man list of instruments used for mission studies to date would enhance plume studies, but these instruments also would be useful for studying the rest of Europa.

The instrument request document acknowledges the science team’s assessment, but states that, “the scientific potential presented by the plumes is sufficiently high that NASA will continue to emphasize the importance of plume investigations and encourages instrument investigations focused on this area.”

Draft summary of findings by the Europa Science Definition Team regarding possible Europa plumes and planning for a mission to that moon.  Entire presentation available here.

While NASA’s management decides the scope of a Europa mission, engineers at JPL continue to refine the design of the current leading concept, the Europa Clipper that comes with an estimated cost of $2.1B.  The current concept would have the Clipper spacecraft make 45 dashes through the radiation fields surrounding Europa for close up looks at the surface and interior.  Building a spacecraft and instruments that can survive that radiation exposure is one of the factors that has driven the cost well above the $1B NASA’s senior managers would like to see.

A presentation made to the science team also provides more insight as to why a large number of encounters are required to study Europa.  The science team has carefully justified what measurements are needed at Europa to understand this world and to enable planning for a lander that would follow the Europa Clipper. 

As an example, the science team has stated a requirement that the composition of 70% of the surface be mapped at resolutions of  less than 10 kilometers by an instrument known as a short-wave infrared spectrometer.  With 45 encounters, this goal would be just missed with 68% of the surface mapped.  (Thirty flybys would map 50% at this resolution or better.)  Similarly, mapping 70% of the surface with an imaging camera at resolutions of 1 kilometer or better would require 38 flybys.  A global distribution of flybys to study the structure of the ice and ocean beneath the surface with an ice penetrating radar would not be met until 43 flybys. 

If the radiation belt did not exist, the next stage to exploring Europa would be to orbit it instead of frantically gathering data during numerous brief flybys.  (Europe, for example, will send the JUICE spacecraft to orbit Europa’s sister moon Ganymede, but that moon lies outside the harshest portions of the radiation belt.)  JPL’s studies suggest that a Europa orbiter would cost about the same as the Europa Clipper, but its lifetime would be so short that the Clipper with its many flybys would better study this moon.

We are left with contrasting opportunities for studying these two worlds.  Mars is close enough and benign enough that both China and private organizations can seriously consider challenging missions.  Europa’s location within harsh radiation belts leaves it as both a technical and a budget challenge.

Tuesday, June 17, 2014

Congress Weighs in on NASA 2015 Planetary Budget

The two houses of Congress have written their proposed 2015 budgets for NASA.  The House bill would add additional funding to almost every category of the Planetary Science budget and would greatly strengthen NASA’s program of planetary exploration.  The Senate bill would add substantial funds to the Mars program but pay for this by cuts to other portions of the planetary budget. 

In American politics, the President proposes federal budgets but it is Congress that decides federal budgets.  Last winter, the President’s budget office proposed a Fiscal Year 2015 planetary budget that was better than proposals for previous years but still well below the levels needed to enact the program laid out by the science community in the Decadal Survey.  Both houses of Congress have now proposed their alternative plans (although the Senate budget has not been approved by the entire body yet).  How has planetary exploration faired? 

It’s useful to start by looking at their changes to NASA’s entire science program.  Each of the science divisions – planetary, astrophysics, heliophysics, and Earth – are operating on budgets well below what’s needed to fulfill the visions in their Decadal Surveys.  However, the political parties have settled on a budget compromise that sets a limit on overall government spending.  Within that limit, the Congressional bills have been fairly generous in proposing increases for NASA’s science programs in lieu of spending on other government programs.  Both Congressional bills would increase funding for astrophysics, but the House favors a substantial increase for planetary exploration while the Senate proposes a modest increase for Earth science (most of which is simply the transfer of satellite programs and their funding from another government agency). 

Changes proposed to the President’s budget for NASA’s science programs.  Credit: V.R. Kane

Within the proposed budget for Planetary Science, both bills propose to increase funding to the Discovery program to enable these small missions to be flown more frequently.  The bills differ substantially though in whether they favor a substantial increase to the Mars program (the Senate) or for defining a Europa mission through increased Outer Planets funding (the House) and to the research and analysis and technology development programs (the House).  Both bills appear to provide funding sufficient to operate all missions already in flight, reversing the proposal in the President’s budget to shut down the Mars Opportunity rover and the Lunar Reconnaissance orbiter.  (The Senate bill does not directly address the latter but does appear to provide sufficient funds for the orbiter.)

Changes proposed to NASA’s Planetary Science Division budgets.  Credit: V.R.Kane

Both the House and the Senate bills propose to increase spending for the Mars program.  The House bill would add $22.7M, a bit more than is needed to continue operating the Opportunity rover as well as all other Mars missions in progress and continue the development of the 2020 Mars rover.  The Senate bill would be much more generous with an increase of $65.7M.  The Senate bill specifically states that it wants to see all current Mars missions continue operating (which would require approximately $15M over the President’s request) but does not specify what the remainder of the funding would go towards.  NASA could use the remaining increase for development of the 2020 Mars rover, which is on a tight budget.

Both the House and the Senate bills would provide increased funding for the Discovery program with the increase targeted to enabling selection of the 14th mission in the series to occur in approximately two years.  (The 12th missions, the Mars InSight geophysical rover is in development and is fully funded, and the selection process for the 13th mission is in progress.)  Both Congressional bills direct that Discovery missions are to be selected every two years in accordance with the recommendations of the Decadal Survey rather than the every five years of the past decade.

If the Discovery program receives funding in future years’ budgets for missions every two years, or five per decade, this is a tremendous boost to NASA’s program. 

Both Congressional bills state the importance of a mission to globally explore Europa, but take very different directions with recommended funding levels.  The House bill would add $85.3M to the Outer Planets budget, which on top of the President’s request would provide $100M to continue preparatory design for the mission.  The House bill directs NASA not to consider any Europa mission that would be substantially cheaper than the ~$2B Europa Clipper it is currently defining.  This is in response to the request of the President’s budget office and NASA senior management seeking ideas for a mission that would cost approximately half as much.  The House bill states that the committee that drafted its bill has not seen any “credible evidence” that a scientifically useful mission could be flown for $1B.

The Senate bill cuts the Outer Planets program by $16.7M, or a little more than $15M the President requested for Europa studies.  (The remaining funds would support the Cassini mission at Saturn and pay for development of US instruments on the European JUICE Jupiter-Ganymede mission.)  The Senate bill gives no explanation for the cut.  In fact, it states in the text that it support’s the President’s funding levels for the Planetary Science program except for increases the Discovery and Mars programs.  The cut to the Outer Planets funding appears in a table, but no explanation is given.

The Senate bill directs NASA to plan to use the Space Launch System (SLS) booster to launch a Europa mission, while the House directs NASA to consider using the booster.  The SLS has the ability to deliver a Europa mission to Jupiter in around 2.7 years compared to a 6.4 year transit if commercial boosters are used.  However an SLS launch would cost ~$1B compared to a few hundred million dollars for a commercial launch.  Congress plans to fund the development and building of several SLS boosters so their cost is already covered. 

While the House and Senate bills both would increase net spending to develop future missions with one favoring Mars and the other Europa, the Senate bill would cause harm elsewhere.  While the House bill supports small increases to the Planetary Science program’s research and technology programs, the Senate bill would impose significant cuts to these programs.  Cutting the research program likely would reduce grants to scientists.  At best, this would stall work to analyze data returned from NASA’s missions.  At worst, this would force a number of scientists and graduate students who depend on these grants to leave the field.

Eventually, the two bills will be reconciled into a single budget that will set NASA’s funding for current and future missions for 2015.  From my news reading, it’s widely expected that the final reconciliation of the House and Senate budgets won’t occur until late this year following the Congressional elections in early November.  

Thursday, June 5, 2014

A Checkup on Future Mars Missions

NASA’s Mars Exploration Analysis Group (MEPAG) recently reviewed plans by Europe, the Japanese, and the U.S. for future Mars exploration.  The prognosis is for another kick ass decade of Mars exploration.

We have enjoyed two decades of increasingly more focused exploration of Mars.  After a lull of twenty years, the 1996 Mars Pathfinder lander began what has became a flotilla of orbiters, landers, and rovers to examine the Red Planet in increasing detail.  Missions in flight or in development will explore the processes that are stripping away the atmosphere, measure its trace gases, and study the interior of another planet for the first time.  Two missions will land rovers to poke and prod two locations in detail.  This is in addition to the three orbiters and two rovers currently exploring this world.  Only for our moon do we have such a rich understanding of another world.

The MEPAG meeting last month included the usual program review, but it also coincided with the second workshop in the long selection process for the landing site for NASA’s 2020 rover mission.  In this post, I’ll share highlights from the two meetings. (You can read the presentations here.)

Credit: J. Green, NASA

The European Space Agency (ESA) has an active Mars program with the Mars Express orbiter currently at Mars, two ExoMars missions in development, and planning under way to select follow on missions.  It will jointly develop and fly the two ExoMars missions with the Russian space agency Roscosmos.  The first, set to launch in 2016, will have an orbiter that will focus on atmospheric chemistry and dynamics along with a small European technology demonstration lander.  The second, to launch in 2018, will deliver a highly capable rover and station that will search for signs of past or present life.

The current tensions between the US and Russia over the Ukraine have the potential for disrupting these missions.  NASA plans to deliver its Electra communications package for the 2016 orbiter that will allow it to relay data from surface landers and rovers back to Earth.  Both ESA’s 2018 ExoMars rover and NASA’s 2020 rover missions plan to use the ESA orbiter to relay data back to Earth.  Because Russia will launch the mission, shipping equipment to Russia with the current political tensions over Ukraine may prove difficult.  With launch just two years away, there’s little time to recover from any delays if they occur.  NASA also plans to deliver a key parts of one of the 2018 rover’s instruments, but there is more time to deal with that issue.

Other highlights from the ESA presentations:
  • Both the 2016 and 2018 missions are on track other than the potential export issue (although no mention was made of whether or not funding has been fully secured for the 2018 mission which has been an open question).
  • Russia is still scheduled to provide the key entry, descent, and landing system for the 2018 rover.  This will be a major project for a space agency that hasn’t had a successful planetary mission in decades.
  • Russia plans to host a surface station in the 2018 lander platform for long-term studies of the atmosphere and geophysics of Mars.  Instrument selection will begin this spring.
  • ESA is considering three missions to follow the 2018 rover.  The current favorite, Phootprint, which might launch in 2024, would be a possible third joint mission with Russia and would return a sample from the Martian moon Phobos.  Other options would be for three small geophysical landers to establish a network to study Mars interior or a small rover to explore a new region of Mars.
Japan’s space agency, JAXA, is considering several mission options for a future Mars mission, but has no currently approved Mars missions.  (It’s only previous attempt to reach Mars, the NOZOMI orbiter, failed.)  For its next try, JAXA’s managers are considering several small missions including an engineering demonstration to use the atmosphere to slow the spacecraft to enter orbit (aerocapture), an airplane to survey magnetic anomalies this will provide clues on Mars’ ancient but now defunct magnetic field, and a meteorological station or seismic station.  The presenter, however, spent the most time describing the most ambitious concept, a rover that would be smaller than the Opportunity rover at ~60 kilograms.  Two goals for the rover were described in some depth – an environmental package to study dust movement by the atmosphere (including dust devils) and a relatively simple microscope that would use fluorescence to detect biosignatures in the soil.  Launch would be sometime in the 2020s.

A presentation on the NASA MAVEN mission that will study loss of the atmosphere into space gave the good news that all is well with the craft.  It arrives at Mars on September 21st this year. 

The Europeans and Russians will not have the only mission to Mars in 2016.  NASA’s InSight geophysics station will launch that year to study the interior of Mars.  The lander also will carry a capable weather station to enable scientists to determine the influence of temperature and winds on its measurements.  The InSight mission has always planned to carry a camera to aid in instrument deployment, with one panorama planned early in the mission.  The project will attempt to replace the currently planned black and white camera with a color camera, but there are no promises.  The mission development is proceeding well and the team has received permission to start hardware development following an in-depth review of the design.

The InSight Mission will greatly enhance our understanding of the interior or Mars. Credit: M. Golombek, B. Banerdt, JPL/Caltech

The focus for the two meetings, though, was NASA’s 2020 rover.  Like the Curiosity rover currently on Mars, the 2020 rover will pursue the question of whether Mars could have hosted life in the past (or even in the present).   While the Curiosity rover does that only with the scientific instruments it carried to Mars, the 2020 rover also will select and cache 25+ rock and soil samples that could be returned to Earth for study with much more sensitive instruments in terrestrial laboratories. 

Credit: B. Ehlmann, JPL/Caltech

In addition to exploring a site in terms of its past habitability, a well chosen site could also allow studies related to the key questions for Mars identified by the Decadal Survey that set priorities for solar system exploration.  The 'Noachian' era was the earliest on Mars when abundant surface water may have created conditions suitable for life.  Credit: B. Ehlmann, JPL/Caltech
NASA plans to build and fly the 2020 mission for just half the cost of the Curiosity mission, adjusted for expected inflation.   The need to collect samples and control costs will ripple through portions of the mission plans.  (An additional new goal, to gather measurements and test hardware that would be useful to a future human mission will also drive some changes.)

One portion of the mission that will be familiar will be the design of the rover and the hardware that delivers it to Mars.  NASA believes that up to 90% of the Curiosity mission’s design (by mass) can be reused (which enables a highly capable mission at bargain price).  Some changes will fulfill the new mission requirements (for example, the caching hardware) and others will apply lessons gained in operating Curiosity (for example, beefier wheels after Curiosity’s showed unexpected early wear). 

The instrument suite the 2020 rover will carry is likely to be substantially different than Curiosity’s.  Curiosity carries instruments that both can make quick measurements to rapidly assess the geology of a location and a highly capable laboratory that can make detailed measurements.  The latter, though, is costly both in dollars and in the time needed to make the measurements.  In almost two years of operation, Curiosity has collected just three samples for its laboratory instruments.  In that same time for the 2020 mission, scientists want to fill most or all of their cache.  As a result, the 2020 rover may carry only rapid assessment instruments in addition to its caching system (although technology advances may mean that some will be much more capable than their Curiosity equivalents).   NASA is expected to announce the instrument selection this July. 

The desire to cache samples also is leading scientists to prize the diversity in evaluating landing sites.  Scientists want its samples to represent the broadest range of ancient environments and processes as possible.  While almost half of the Martian crust is older than 3.7 billion years when life might have formed (compared to less than 1% for the Earth), many of those locations would provide limited diversity within the range a rover could explore.  (Many also would be unsafe to land at.)

The NE Syrtis Major site (second from the bottom) has a wide range of diversity.  This chart is a draft and may change as the diversity of other sites is further assessed.  Credit: B. Ehlmann, JPL/Caltech
At the end of the landing site workshop, the participants held a straw vote to indicate which sites they found most compelling.  The winner, located on the northeast edge of the plains of Syrtis Major, illustrates the diversity they would like to find.   Within a few kilometers, this site provides access to samples that record key stages of Mars’ early evolution:
  • Blocks of rocks hurled from nearby massive impacts record the early bombardment of the terrestrial planets by comets and asteroids.  These are also convenient samples of the ancient crust delivered from outside the landing zone.
  • Ancient crust with minerals preserving the record of the early wet environments of Mars that may have provided conditions for life to develop or at least that record biotic precursors.  The NE Syrtis Major site has an unusually wide range of aqueous minerals that suggest a diversity of environments that came and went across millions of years as the climate dried out.
  • A nearby volcanic flow represents the massive volcanism that covered large areas of the planet in its early history.  These rocks could record the chemistry of Mars’ ancient mantle, provide clues on when Mars’ ancient magnetic field shut down, and in terrestrial laboratories provide unambiguous dating of a wide-scale event to calibrate dating of Mars’ early history.

Location of the proposed NE Syrtis Major landing site.  Credit: J. Mustard, Brown University

The proposed NE Syrtis Major landing site includes geologic formations from the two most ancient eras on Mars, the Noachian and the Hesperian.  The site has remnants from ancient impacts, several types of aqueous minerals, and access to volcanic rock formations.  Credit: J. Mustard, Brown University
At this point, NASA is not looking to rule out any of the nearly thirty sites that have been proposed.  While the NE Syrtis Major site won the initial beauty contest, other sites may prove to be more desirable with further analysis.

While NASA doesn’t need to select the 2002 mission’s landing site until 2019, two factors are pushing it to evaluate sites early.  One is that high resolution mapping of the sites for geologic sites and landing hazards requires the sharp-eyed cameras of the Mars Reconnaissance orbiter.   That spacecraft reached Mars in 2006, and NASA wants to make maximum use of it while it remains healthy and has an adequate fuel supply.

The mission’s engineers also want an early look at the most desirable landing sites to determine whether the 2020 rover will need a significant upgrade in its landing system.  The closest the mission’s operators currently can target the lander is to an ellipse 25 by 20 kilometers.  A simple design change can reduce that ellipse area by 40%.  Unfortunately, the richest sites for exploration often don’t have the smooth surfaces needed to ensure a safe landing within their landing ellipses.  The Curiosity rover, for example, will spend more than two years getting from its safe landing site to the starting point for its actual target area.  (Fortunately, there’s been great science along the way.)

For the 2020 mission, NASA would like to avoid another long road trip at the start of the mission.  If the sites of greatest interest turn out to turn out to have hazards, then NASA will consider a technology called Terrain Relative Navigation (TRN).  With TRN, the landing system will compare images taken during the final descent against a stored map of safe landing zones.  It will then steer the landing to one of those safe harbors.  Without TRN, a mission to the NE Syrtis Major site, for example, has an 87% chance of a safe landing; with TRN the chance of safe landing increases to over 98%.  However, the TRN technology would be expensive to develop and test.  NASA wants to know that it is likely to be needed before committing to it for a mission that’s already being done on a bargain budget.

The two meetings showed that despite an incredible run over the last couple of decades, for Mars the best may still be to come.

Note: All the presentations promoting landing sites from the landing site workshop are available on-line.  If you’re not a geologist, you may want to read Emily Lakdawalla’s posts on Mars’ geologic eras and on key minerals that suggest past aqueous environments.  Wikipedia also has articles on the Noachian era and  its successor the Hesperian era during which Mars’ surface transitioned from an impact ridden world, to one with possible abundant surface water, and then progressively dried out.  The 2020 mission is likely to focus on sites that contain remnants from one or both of these eras (as the NE Syrtis Major site does).

Saturday, May 10, 2014

A Reluctant Dance Towards Europa or Why A Credible Europa Mission is Likely to Cost ~$2B

For the last two years, NASA has been the shy partner refusing to get on the dance floor, and Congress has been the aggressive partner insisting on a dance now.  Recently, NASA has said maybe on another night but only if it’s a cheap date.  While NASA says no for now, Congress looks to be willing to slip the band a cool $100M – on top of $150M already paid – to keep the music playing, but (to keep the metaphor going) has not been willing to fully commit itself to paying the bigger bill to rent the dance hall.

The dance, of course, is the continuing attempt by Congress to have NASA commit to a mission to explore Europa, and NASA’s attempts to delay a mission well into the 2020s.  NASA is also seeking ideas for alternatives to the current $2B Europa Clipper concept that would cost no more than $1B but that also would presumably be less capable.

Compared to the budget waltz, the scientific case for a mission to Europa is compellingly simple.  After the Earth, Europa is considered by many scientists to be the most likely location in the solar system as a home to present life.  It has the key ingredients: an outer layer with lots of water (more than in the oceans of Earth) in contact with the rocky core (source of key elements needed to build the molecules essential for life) and energy (from the tidal heating supplied by Jupiter).  And Europa has had a lot of time for life to evolve.  Its oceans should have been present for most of the life of the solar system.  (This distinguishes it from Enceladus where the weaker tidal flexing of Saturn may allow its internal ocean to freeze for long periods of time.)  The recent observation of possible plumes spewing water into space where Europa’s ocean could be easily sampled has just raised the desire for a dedicated Europa mission.

The Europa Clipper would replace a short-lived Europa orbiter concept with a spacecraft that would fly past the moon several dozen times with a highly capable instrument payload.  At each encounter, the instruments would do low- to medium-resolution studies before and after closest encounter, but would do high resolution studies during the brief period when the spacecraft is less than 1000 km from the surface .  Credit: NASA/JPL.

The Science Goals

In the 1990s and early 2000s, the Galileo orbiter made eleven of flybys past Europa.  That mission all but proved the existence of a liquid ocean beneath the moon’s icy shell and globally mapped the surface features and composition.  Galileo, however, had a crippled main antenna that reduced the returned data to a tiny trickle of what had been planned, so medium and high resolution mapping of the moon covers only small areas.  The spacecraft’s vintage 1970’s technology instruments also lacked the sophistication to identify important substances in the icy surface.  It also did not carry instruments that could probe the structure of the icy shell to look for lakes within the shell or study the shell’s interface with the ocean. 

The standard progression for exploring a world is first flyby it (which Galileo did), then orbit it for globally studies, and then land on it for intensive studies in a single location.  Unfortunately, Europa sits well within Jupiter’s harsh radiation belts, and any affordable orbiter would have weeks to a handful of months to complete its studies and would carry a minimal instrument compliment.

JPL’s engineers and scientists have developed an alternative strategy for the proposed Europa Clipper mission: Fly a highly capable spacecraft that orbits Jupiter, but that toe dips into the radiation belt and conducts its science during several dozen flybys.  The radiation challenges are still significant, but the science that would have carried a cost of >$4B as an orbiter can now be done for ~$2B.

The several dozen flybys is key to the Europa Clipper’s ability to replace an orbiter mission with a multiple-flyby mission.

During the few minutes around closest encounter, high resolution studies are done only for a narrow swath along the ground track immediately below the spacecraft's flight.  Credit: NASA/JPL.

Over several dozen flybys, the high resolution measurements build up into regional studies.  Credit: NASA/JPL.

The combination of low, medium, and high resolution measurements add up to an understanding of Europa as a world over several dozen orbits.  (Acronyms: 13F7 - name for a specific concept for a set of flybys; COT-4 - name for the final campaign (of four) for the Europa Clipper mission; SWIRS - Short-wave infrared spectrometer that would map the composition of the surface.)  Credit: NASA/JPL.
I’ll focus on just one set of requirements and how they link to several key investigations.  To ensure that proposed mission achieves global coverage, the science team has divided Europa’s map into 14 panels.  The science goals require that the spacecraft fly over at least 8 of these panels at altitudes of less than 400 kilometers with a desired goal of 11 panels.  Within each panel, the requirements specify that at least two close flybys occur in each on the Jupiter-facing hemisphere of Jupiter and three on the anti-Jupiter face.  If the minimum 8 panels are evenly distributed between the pro- and anti-Jupiter hemispheres, then 20 flybys are needed to meet the minimum science goals.

This one set of requirements for regional measurements within a panel and a distribution of regional studies across the Europan globe enables several key studies:

“Characterize the ice shell and any subsurface water, including their heterogeneity, ocean properties, and the nature of surface-ice-ocean exchange.
·         “Characterize the distribution of any shallow subsurface water and the structure of the icy shell.
·         “Search for an ice-ocean interface.
·         “Correlate surface features and subsurface structure to investigate processes governing material exchange among the surface, ice shell, and ocean.
·         “Characterize regional and global heat flow variations.
“Understand the habitability of Europa's ocean through composition and chemistry.
·         “Characterize the composition and chemistry of the Europa ocean as expressed on the surface and in the atmosphere
·         “Determine the role of Jupiter's radiation environment in processing materials on Europa
·         “Characterize the chemical and compositional pathways in Europa's ocean.
“Understand the formation of surface features, including sites of recent or current activity, and characterize high science interest localities.”

The science goals similarly require a number of well distributed flybys to study the interaction of Europa’s ocean with Jupiter’s intense magnetosphere to estimate the depth and salinity of the ocean and to study tides to estimate the ice shell’s thickness. 

The current Europa Clipper mission concept goes well beyond the minimum science goals to deliver on almost all the extended goals that the science community has set.  However, cutting the current mission concept from its 45 Europa flybys to a minimum of 20 or fewer flybys seems unlikely to cut the mission costs in half.  Once you build and fly a spacecraft to Europa that can withstand 20 encounters, operate a suite of instruments, and return a large volume of data between encounters, I suspect that you've already incurred most of $2B cost (but remember that I am neither an engineer nor a planetary scientist). 

Is Cheaper Credible?

NASA managers have formally asked if a credible Europa mission could be done for half the Clipper cost estimate, or around $1B.  This is a good news/bad news scenario.  NASA took the initiative to propose an in-depth study by suggesting spending $15M next year ($85M less than the House of Representatives appears ready to approve for next year, see below).  However, next year’s study would be followed by several years before any mission conceived would actually begin development and a decade or more before it might launch.

NASA issued a Request For Information on concepts for a $1B mission.  It has required that proposers, “meet the majority of the five science goals set forth in the Decadal Survey [priorities set by the scientific community], including the goal to characterize scientifically compelling sites to prepare for a potential future lander mission to Europa.”  Those scientific goals are, in priority order, to:

” Characterize the extent of the ocean and its relation to the deeper interior;
“Characterize the ice shell and any subsurface water, including their heterogeneity, and the nature of surface-ice-ocean exchange;
” Determine global surface compositions and chemistry, especially as related to habitability;
 “Understand the formation of surface features, including sites of recent or current activity, and identify and characterize candidate sites for future in situ exploration;
” Understand Europa’s space environment and interaction with the magnetosphere.

“While characterizing landing sites for future in situ exploration is the fourth scientific priority in the Planetary Decadal Survey, NASA places high programmatic priority on this goal to enable a potential future lander mission to Europa.” (From the Request for Information.)

The request goes on to list the challenges of implementing the mission.  “The primary challenges facing any mission to Europa involve the harsh radiation environment and planetary protection requirements… Planetary Protection requirements for Europa are very strict and involve ensuring that the probability of introducing a viable Earth organism into Europa is [less than one in 10,000].”

The request's details make it clear that proposers must do a solid amount of science and engineering analysis to show that they have a credible concept that could cost less than $1B (not including the launch costs) and make their case in 15 pages

It is common for government agencies to issue these “Requests for Information” to learn whether an idea is credible and worth pursuing.  This request doesn’t commit NASA to any follow up studies, but if its managers judge any of the proposals to be credible, it presumably would follow through with more detailed analyses.

Is a $1B mission idea credible?  I did a thought experiment in a previous post and concluded that technically it likely is.  The Juno spacecraft that will orbit and study Jupiter cost ~$700M.  A mission to fly by Jupiter’s moon Io, deeper in Jupiter’s radiation field, six or so times has been estimated to cost ~$1B.  The European’s JUICE mission will reach Jupiter next decade, flyby Europa twice, and then orbit the moon Ganymede for ~$1.2B.  

If the goal simply is to fly by Europa a few times with a spacecraft with a small number of instruments, then by analogy with these other Jupiter missions, it likely can be done for ~$1B.  The bar, though, for a scientifically credible mission is higher.  A follow-on mission has to substantially enhance our scientific understanding of Europa to justify a cost of $1B to $2B.  Most of the key studies identified by the science team require numerous flybys distributed across the globe.

However, Europe’s JUICE 2020’s JUICE mission to the Europa system is committed to two flyby of Europa with a highly capable spacecraft and instrument suite.  To be justified, a NASA mission must produce significantly better science than the already funded JUICE mission will.  (While the JUICE mission, which is still in design, it has committed to just two flybys of Europa. I suspect that if the engineers conclude it is safe, the mission’s managers will consider one or two additional flybys closer to launch.)

So is there hope for a $1B mission that is scientifically compelling?  Color me skeptical (and several of NASA’s managers are reported to have said they  are skeptical, too), but if there is, I suspect that it will come in one of two forms:
  • A proposal suggests a clever way to redefine the science goals in a way that returns the core science with a simpler and cheaper spacecraft.  The team that proposed the Juno mission on its way to Jupiter did this for studies of Jupiter’s deep atmosphere and interior.  The current Europa Clipper multi-flyby proposal redefines the science goals from previous orbiter proposals to substantially cut costs.  Is there another option that can cut costs substantially again?
  • A proposal combines limited regional studies with flights through the possible plumes of Europa to directly measure water, and possibly life, expelled either from a lake within the shell or directly from the ocean.  (However, remember that only one of several studies saw data that suggested plumes were present and those measurements were near the limit of detection.  The plumes may be ephemeral or not even exist.  Justifying a mission on the current plume data seems risky to me; a better strategy would seem to be to have a viable mission without the plumes but carry the already planned instruments that would also be useful to study the plumes.  The JUICE mission team is already planning this.)

In a few months, we are likely to learn whether NASA received any proposals it considers worthy of further study.  They key, though, will be whether the science community agrees that the mission meets the core requirements for understanding Europa.  If it doesn't, then the community seems likely to recommend waiting until budgets allow the right mission to be flown.  Missions to each outer planet or their moons occur only every couple of decades.  Why do a sub-par job on the next mission to Europa and then have to do it over a decade or two later to get it right?

The Politics

In the introduction to this post, I said that NASA (and the President’s budget office that writes NASA’s budget requests) and Congress disagree on whether a Europa mission should begin now or wait to begin development several years from now.

The root of the disagreement, as in so many relationships, is money.  Jupiter’s harsh, electronics-frying radiation belts, make any mission that does more than a handful of flybys a technically challenging – read expensive – proposition.  More than a decade’s worth of technology development and mission studies has provided the solutions to most of the technical challenges.  JPL’s scientists and engineers have developed a killer proposal for a dedicated multi-flyby Europa Clipper mission.  At ~$2B, this mission would be cheaper than the Curiosity rover mission currently exploring Gale crater on Mars.

Unfortunately, NASA’s budget is oversubscribed.  The only way to fit the Clipper mission into the budget is to either increase NASA’s budget by several hundred million dollars a year for several years (which I would support as a US taxpayer!) or take the funding from other NASA programs. 

We are left with this strange waltz in which Congress, which ultimately sets NASA’s budget, has not increased the overall budget enough to fully fund the Clipper mission, but over the last two years provided $150M for advanced development work.  This year, the House of Representatives is proposing to put another $100M in the pot for next year.  If the Senate continues its previous support, it is likely to substantially match this funding. 

At the other side of the dance floor, the President’s budget managers and NASA’s managers have made it clear that they don’t want to commit to any Europa mission this decade because of the funding constraints.  They also seem reluctant to commit to any $2B-class science mission because the last two large science missions (the James Webb Space Telescope and the Curiosity rover) went well over budget, which caused substantial harm to the overall science program. 

As a result, today NASA is spending $150M because it’s legally required to (Federal budgets in the US are laws) to advance a mission its senior managers don’t want to do, at least for this decade. 

The House of Representatives has released details of its proposed budget for next year.  Where NASA proposed to spend $15M to study $1B mission concepts, the  House is proposing to spend $100M.  Under the House’s bill none of the funding could go towards a $1B mission (which it doesn't see as credible) but only towards the full Europa Clipper mission. 

We will have to wait for several weeks to see what the Senate proposes.  It will be several months before we learn what the two houses of Congress ultimately compromise on for next year.

Wednesday, May 7, 2014

2015 Budget Micro-management of the Best Kind

The US House of Representatives has just released the details of its draft proposed NASA budget for Fiscal Year 2015 (starting October 1 of this year).  For planetary science it is good news all around.  In fact, it’s great news because the proposed spending bill micro-manages NASA’s budget to bring NASA’s planetary program closer to the plan laid out in the scientific community’s Decadal Report outlining goals for the coming decade. 

While it is easy to become cynical about politics, it is clear that in this case the politicians and their staffs from both parties on the subcommittee that wrote this draft budget are familiar with the details of the planetary program and are following the scientific community’s lead.  Instead of giving unfunded mandates, all the changes they request are accompanied by proposed increases above the President’s budget proposal.

Missions to Europa would be the big winners in the draft budget bill.  Credit: NASA/JPL/Ted Stryk

President's Budget
House Draft Budget
Planetary Science Research and Analysis
New Frontiers
Mars Exploration
Outer Planets
Total Budget

Changes to the President’s budget request in the draft House budget bill in millions of dollars.  Courtesy of Casey Drier at the Planetary Society

In this post, I’ll let the House subcommittee speak for itself through key quotes from the proposed budget bill (starting on page 67).  For the larger context of the budget in Washington’s politics, I encourage you to read Casey Drier’s post at the Planetary Society blog.

“NASA’s request for Planetary Science once again represents a substantial decrease below appropriated levels and would have a negative impact on both planned and existing missions. The recommended funding levels [in this bill] attempt to rectify this problem by supporting both the formulation and development of new Planetary Science missions and the extension of all healthy operating missions that continue to generate good scientific output.”
- The budget provides the funds to continue operating all NASA missions that are currently operating.  The President’s proposed budget did not have funds for either the Mars Opportunity rover or the Lunar Reconnaissance Orbiter.  Money is also provided to continue the Cassini mission at Saturn, which was also included in the President’s budget request.

…”$302,000,000 for Mars Exploration, of which not less than $100,000,000 is for a Mars Rover 2020 that meets scientific objectives laid out in the most recent Planetary Science decadal survey.”
 – This is a modest $8M increase over the President’s budget.  The key requirement is that the rover must meet the requirements laid out in the Decadal Survey, which means that that it must be capable of selecting and caching samples for a possible return to Earth for studies in terrestrial laboratories.  This has been NASA’s plan, but the final payload – the ultimate expression of the mission’s goals – hasn’t been announced, and this is the House’s way of ensuring that NASA follows through.

“The recommendation also provides $266,000,000 for Discovery, of which not less than $30,000,000 is for Future Discovery Missions. The Committee notes that NASA allowed a four year gap to develop between the release of the last Discovery Announcement of Opportunity (AO) in fiscal year 2010 and the expected release of the next AO in fiscal year 2014 (a gap which would have been worse were it not for additional resources provided by the Congress). In order to prevent the recurrence of such a gap in the future and to firmly establish the 24 month mission cadence recommended by the Planetary Science decadal survey, NASA shall ensure that the planned 2017 Discovery AO is issued instead during fiscal year 2016.”
- Selecting Discovery missions every two years instead of every five would significantly enhance the number of planetary missions NASA flies.  The bill adds $30M to the Discovery budget to accelerate the rate at which missions are flown.  This will be big news if the Senate follows suite and this is part of the final budget law.

“For Outer Planets, the recommendation provides $181,000,000, of which not less than $100,000,000 is for a Europa Clipper or comparable mission that meets the scientific objectives laid out in the most recent Planetary Science decadal survey and can be launched in 2021. This funding shall support the completion of science definition, the selection of a mission concept, the release of an instrument AO and other necessary pre-formulation and formulation activities for the Europa mission. While NASA has dedicated some fiscal year 2014 Europa funding to studying the possibility of conducting this mission within a $1,000,000,000 cost cap, the Committee has not seen any credible evidence that such a cost cap is feasible and directs NASA not to use further project resources in pursuit of such an unlikely outcome.”
- The House subcommittee that wrote this budget language continues to strongly support a highly capable mission to Europa.  NASA has formally requested proposals for a mission that would cost half as much as the proposed $2B Europa Clipper mission, but that likely would do much less science that specified in the Decadal Survey.  It will be interesting to see if the Senate includes similar language in its version of NASA’s budget.  If this language survives into the final budget, this will be a strong directive to NASA to plan for a highly capable Europa mission.

“For Planetary Science Technology, …$18,000,000 shall be for assessments and development of promising technologies and techniques for the study and characterization of the surface and subsurface of Europa, including such technologies as landers, rovers, penetrators, submersibles, seismometers and sample analyzers.”

- The House subcommittee really likes Europa.  A mission to land on Europa would have to follow the Europa Clipper mission that would scout possible landings sites.  This is an investment in technology for a mission that isn’t likely to fly until the 2030s.