Monday, June 18, 2012

Mars Concepts and Approaches Workshop

NASA's Mars Concepts and Approaches Workshop was held last week to gather the best ideas for moving forward with Mars exploration from 2018 on.  In my last post, I described ideas for a new generation of small Mars rovers in the class of the Spirit and Opportunity missions.

Dozens of ideas were presented.  Travel prevented me from listening in to the sessions.  However, planetary geologist Philip Horzempa who has a long term interest in future mission planning was able to follow the workshop.  He was kind enough to gather his thoughts and views on the ideas that were presented:

Report on "Mars Concepts and Approaches" Workshop of June 2012
  This NASA-sponsored conference was a way to reach out to the larger Mars community for suggestions on re-planning the Mars Exploration Program (MEP) at the space agency.  During 3 days of discussion, an amazing variety of concepts were presented.  These ranged from discussions of entire missions to proposals of individual instruments.  I was not there in person, but was able to experience some of it virtually, through NASA's webcast.  The overall impression that I got was that there is a lot of interest in approaching Mars exploration in a smarter fashion.  The hope is that this will lead to missions that are affordable in the new, constricted budget environment.  One aspect of this workshop that may have been overlooked is the involvement of NASA's manned spaceflight division, formally called the Human Exploration and Operations Mission Directorate (HEOMD).   Much of this involvement may be traced to the MEPAG meeting in February of this year.  Perhaps to allay the shock and chagrin of scientists over White House plans to cut funding for the MEP, NASA formulated the P-SAG, the Precursor Science Analysis Group.  Its charter was to examine any overlap in goals between the manned and robotic Mars programs. Their report, completed at the end of May 2012, listed numerous Strategic Knowledge Gaps, or SKG's, that need to be filled before we launch manned missions to Mars.  It is interesting to note that Mars Sample Return (MSR) is one of the top priorities of both P-SAG and the recent Planetary Decadal Survey. 

Orlando Figueroa, the leader of NASA's Mars re-planning effort,  pointed out that one reason for this workshop was to see how manned and unmanned programs could cooperate.  It appears that an MSR mission, or series of missions, may be one of those areas of cooperation. 

  In addition to manned spaceflight, NASA's Office of the Chief Technologist, the OCT, will be part of the new cross-agency Mars effort.  This trio should make for an interesting partnership.

   One factor in this cooperation is funding.  With the MEP program heading for financially lean times, the manned program, and the OCT, may be contributing to the pool of funding for future Mars missions.  This additional funding may allow more ambitious missions, such as sample return.  So, a Mars mission in 2018, and those that follow, may be serving, in addition to their role as robotic explorer/scientist, as Precursors for future manned missions, as well as technology testbeds .  Science may need to share the ride in order to get to Mars at all.

    The Concepts workshop opened with reference to the manned Mars roadmap.  NASA has been "directed" by President Obama to send a manned mission to orbit Mars post-2030.  Doug McQuiston, of NASA Headquarters, reported that the agency is using this as guidance in developing plans for Mars exploration.  To give that plan a focus, NASA has chosen the April 2033 Mars launch window as the target for launching a manned mission to Mars orbit.  They will then track back from that date to gauge what needs to be done to prepare for it.  It was pointed out during this workshop that, because the first manned Mars mission is now an orbital mission, the crew will not benefit from the radiation protection afforded by Mars' atmosphere.  As a result, the emphasis is now on doing a fast mission - get to Mars, and get back quickly - in order to lower exposure time for the crew.  This will influence NASA's decisions on propulsion and trajectory for that mission. 

    Another note on the manned side of the ledger concerns the delay of the first manned landing mission.  While the Constellation program was in effect, a relatively near-term Mars landing meant that NASA engineers could not consider such enabling technologies as In-Situ Resource Utilization (ISRU).  They needed to stay with proven technology.  NASA's detailed plan for this, DRM (Design Reference Mission) version 5.0, was referenced at the meeting. With the landing put off to some indefinite time, they now have the liberty to consider technology options that are not yet mature. 

   The workshop presentations were numerous and for the most part fascinating.  I will pick several that caught my attention.  These will be only a small sample of the plethora of ideas submitted to the conference.  There were a total of about 175 oral presentations, as well as approximately 150 print-only reports.  This collection of proposals is a valuable resource for NASA as it charts a new path forward for Mars exploration.  It is remarkable how far the technology needed for that exploration has advanced in the past 10 years.

    Van's previous post mentioned the modernized MER rover.  This design was referenced by several proposals, including a Mars Polar Rover.  As Van pointed out, this MER-class rover is being looked to as a caching rover, possibly for the 2018 launch window.  This would serve as the 1st step in an MSR campaign.   I think that I caught a bit of a pushback to this high priority for MSR.  This is reflected in the proposal, that Van referenced, for a multi-year MER caching campaign.  This would see 1 or 2 MER-class rovers sent to Mars in every launch window over a decade.  This would result in landing at 5 - 10 individual sites.  The MER-class rovers would serve 2 purposes - expanded exploration and caching in preparation for MSR.  At the end of the decade, there would be 5 - 10 caches waiting on the surface of Mars, waiting for a retrieval mission. 

  In addition to the MER-class rovers, there were proposals for many mobility options.  There were smaller, lighter, simpler rovers.  There were unmanned airplanes, helicopters, kites, hoppers, "tumbleweeds," "maple seeds" and balloons.  One of the "edgier" methods involved a dragonfly-like entomopter that looked like it came out of a Star Wars movie (1).  It would use a MER-class rover as a mobile base for the robot "insects."

   Other mobility concepts attacked the challenge of sites with steep slopes, such as caves and skylights.  One concept showed a video of a robotic hand that could grip rock surfaces, much as a free-climber does on the Earth. (2)  Amazing. 

  In connection with MSR, there were a variety of proposals that addressed ways of making sample return more feasible, both technically and fiscally.  One area of focus was the use of ISRU in providing propellant for a Mars Ascent Vehicle (MAV).  There have been many ISRU proposals over the years, but this workshop saw new twists on the story, including one in which Magnesium is burned to provide thrust for a MAV (Mars Ascent Vehicle) using Carbon Dioxide drawn from the atmosphere or water from ice deposits (3).  

    There were numerous other ISRU concepts set forth.  A near-term mission that would test ISRU on the surface of Mars seems to be of interest for both manned and unmanned programs.  The new thinking at NASA regarding manned Mars surface missions is that the agency would like to see supplies waiting for a crew.  Those expendables would need to be generated by automated ISRU.  This is one example where the delay in a manned Mars landing may allow the use of an enhancing technology. 

    Another popular area of interest was the use of Solar Electric Propulsion, SEP, in the Earth-return step of MSR.  Many sample return scenarios now seem to be concentrating on the "tough" part, i.e., collecting samples and getting them safely into orbit around Mars.  Once that is accomplished, many appear to assume that a SEP "tug" could collect the orbiting sample canister, then slowly spiral out of Mars orbit, returning to the Earth, or possibly Earth's L2 location. Sample return using SEP would take longer, but would allow the return of a greater mass of samples, as well as reducing the cost. 

In addition, the use of an SEP vehicle allows a wide dispersion of parking orbits for the sample canister.  This in turn, means that the guidance system of an MAV can be simple, even rudimentary, and therefore cheaper.     As with ISRU, SEP seems to have "turned the corner" in the minds of Mars mission planners.  At meetings such as this, some ideas seem to experience a wave of acceptance.   This seems to have occurred with ISRU and SEP. 

   One out-of-the-box proposal for a cheap method of getting samples from Mars orbit to the Earth's vicinity would utilize Interplanetary Cubesats (4).  This proposal would use a version of ion propulsion, Microfabricated Electrospray Propulsion, MEP.  This is a newly-developed technique, using Indium as propellant.  Like SEP, this concept would slowly transport samples from Mars orbit to the Earth's L2 location.  If NASA sets up a manned Waypoint Base at L2, then the robotic sample return vehicle need not include a heat shield and Earth-landing system.  If the samples are examined for life at this Waypoint, an Earth-based biological isolation laboratory need not be built. 

   As for landing on Mars, this workshop saw the introduction of 2 new EDL (Entry, Descent and Landing) methods.  The first would be utilized by the ATHLETE rover (5).  This concept envisions using a MER-derived aeroshell and heat shield.  However, instead of MER's bouncing beach ball of airbags, ATHLETE would use an SRM to cancel out most residual velocity near the surface.  It would also use 3 MLE (Mars Landing Engine) thrusters developed for MSL, with the use of a single vented airbag for surface contact.

   The other new EDL system would use Space-X's Red Dragon design (6).  This would see the use of Dragon's Super Draco thrusters, originally designed for launch abort, to deliver a high-g retro-burn.  This would be a nail-biter, as the burn takes place supersonically, not far above the surface.  This method may need a demo mission, perhaps funded by Space-X to make people comfortable with using it. 
   The Red Dragon capsule design was referenced in several proposals, as people see this as a possibly FBC method of delivering instruments to the surface of Mars.  It has an interior volume of 3 cubic meters, and can transport 1,000 kg to the red planet, allowing a range of payloads. 

   One of my favorite mission concepts is the Ground Breaking MSR, or GBM.  Since the MEP's recent budget free-fall, this mission has made a comeback.  There were several proposals for just such a mission. The logic behind a GBM is that it is simple, thus cheaper.  It is noted that the more complex scenarios for MSR have not gotten approved over the past 2 decades, primarily because of sticker shock.  With the overruns in the MSL and JWST programs, Congress and the White House may be very reluctant to sign on to a multiyear, multi-spacecraft, multi-billion-dollar program.  The logic behind GBM is one that follows the model of the MoonRise New Frontiers proposal.  That mission was designed to collect local samples, encapsulate them, and launch them to the Earth.  No rovers, no multi-core cache.  The GBM's at this workshop envisioned using the Phoenix lander as a base for a sample arm and the MAV. 

   Several proposals were made regarding variations of an MAV.  One of these would test launch an MAV to Mars orbit, again using the Phoenix lander as a base. (7)  This may be one of the less expensive missions, and would satisfy NASA's requirement that the 2018 mission be on the path to MSR.   In the print-only reports, there is a presentation by John Whitehead that I believe summarizes the very real risks of any Mars Ascent Vehicle design (8).  He stresses that there should be no complacency when it comes to building and flying an MAV.  There has never been a launch from the surface of Mars, and there is no rocket system in existence that resembles the MAV.  He points out that there is no comprehensive MAV development program at NASA.  His warning should be read by all scientists involved in MSR.  I was concerned to hear comments by participants of this workshop that indicated that they thought building an MAV was "blue-collar" work, i.e., not all that difficult.   The truth is that they should be worried.  Launching a sample canister and putting it into Mars orbit is a formidable task.   

   One other area of concern for MSR is reliable detection of the sample canister in Martian orbit by the Earth-return spacecraft.  It is possible that several years will have elapsed between the injection of the canister into orbit around Mars and the arrival of the Earth-return vehicle.  Whether that return craft uses SEP or MEP or old-fashioned chemical propulsion, it will still need to find the canister.  A print-only paper proposes a test of a system that could do that (9). It would use MRO's Op Nav Camera, the ONC, to find the Mars Global Surveyor spacecraft that went silent a few years ago.  It is still in Mars orbit and serves as a stand-in for future sample canisters.  This would be a proof-of-concept and would "buy down" the risk for this step in the MSR train of key events.  As a bonus, the ONC could be used to track down other historic Mars Orbiters such as Mariner 9 and Viking Orbiters 1 and 2. 
  One of my impressions from these proposals is that sensor technology is advancing so rapidly that the science case for MSR may be eroding over time.   As a geologist, I am impressed that the age-dating Rover could pin down ages to a range of 60- 90 million years.  That may seem like a big error range, but really is not significant when one is dealing with rocks that have ages of 1,000 - 4,500 million years.  That is impressive accuracy for a remotely-measured age determination.  It is just one example of the impressive technology showcased at this conference.  Another is the proposal to fly a petrographic microscope to Mars.  This is one of the oldest and most valuable tools of a geologist.  It literally enables a scientist to see the minerals that make up a rock.  If it can be shown to work on another planet, I believe that yet another scientific justification for MSR would disappear. 

  There was an update on the ExoMars program from an ESA representative.  After the joint Roscosmos / ESA missions of 2016 and 2018, there are 2 proposed missions.  One is PHOOTPRINT, a sample return mission to Phobos.  It is unknown how much of the Phobos-Grunt heritage would be used in this mission.  The other concept is INSPIRE, a geophysical network mission that would utilize 3 landers.  It has not been decided which mission will launch in 2022, with the other to follow in 2024.

  There were several personalities of note at this workshop.  One was Rob Manning, an engaging EDL engineer with experience that reaches back to the Mars Pathfinder mission.  He was advocating one of the Ground Breaking MSR options (10).  He commented that he has witnessed why Pathfinder cost so little, and why the MSL rover costs so much.  It comes down to complexity.  As that increases, the cost expands "fractally."  Mr. Manning emphasized simplicity and taking small steps in the effort to achieve MSR.  He pointed out that MER could not have succeeded without Pathfinder, and MSL could not have gone forward without MER. 

 Another personality of note was Robert Zubrin.  For many years he has been an advocate for a vigorous program of Mars exploration.  At this meeting, his presentations and comments were sharp and insightful.  One of the cases that he argued concerned the planetary protection guidelines that are imposed on Mars surface missions.  He pointed out that these were putting excessive, and perhaps unnecessary, burdens and expenses on Mars missions.  There seemed to be a lot of agreement with his logic.

 It was inspiring to see that astronaut Buzz Aldrin was in attendance.  He is an engineer and, even though he knows that he will never get to Mars in person, he was giving his time and energy so that future generations will fulfill that dream. 

  Gathering these, and many other, key people at one place, at one time, was one of the prime achievements of this workshop.   Perhaps, NASA should hold meetings like this every 2 - 4 years to serve as a way to encourage, and gauge, new developments in Mars exploration technology. 

  There was a suggestion at the workshop that NASA issue an AO (Announcement of Opportunity) for the 2018 Mars launch window.  It would have a cost ceiling of $700 million.  Since this may include the cost of launch, the chosen mission will need to be minimal in nature.  My vote would go for the MAV launch demo of Chandler, as this has a good chance of staying within budget, while at the same time demonstrating technology crucial to MSR. 

Philip Horzempa

- - - -

5.  "Low-CostAthlete-Based Mars Lander/Rover," by C. McQuin and B. Wilcox 
8.  "A Perspective onMars Ascent for Scientists," by John Whitehead
10. "Toxicity Sample Return Tech Demo," by Brian Muirhead et al.

Monday, June 11, 2012

Next Generation MERs for Mars?

Example of proposed upgrades to the basic Mars Exploration Rover design for missions to Mars in 2018 and beyond.  This particular upgrade would enhance the rover with next generation instruments and add capabilities to collect and cache samples for eventual return to Earth.  The full abstract is available here.

This week NASA will hold its conference on Concepts and Approaches forMars Exploration.   The space agency will use this meeting to hear new ideas for exploring the Red Planet.   The planetary science community responded with a wide range of ideas for both future robotic and manned missions.   The best ideas presumably will be incorporated into NASA’s new Mars exploration plan for 2018 through 2033 to be released this summer.

Extended two page abstracts for most of the talks have been posted at the website, and I use them for the information in this and probably the next several posts.

A wide range of robotic missions will be proposed from orbiters to explore the subsurface with ground penetrating radars to rovers that would be blown like tumbleweeds by the winds across the surface. 

A number of the talks will propose new rover missions that would reuse the basic design of the Mars Exploration Rovers (MER) (see, for example, this abstract).  This is the design used by the highly successful Spirit and Opportunity rovers currently on Mars.  By reusing a proven design for entry, descent, mobility, and science operations, costs of future missions would be substantially reduced.  One talk will propose that five to ten rovers be delivered in the 2020s to both explore different regions of Mars as well as to possibly carry different instrument compliments. 

In terms of size, the MER design is much smaller than the Curiosity rover en route to Mars for a landing this August or the planned ExoMars rover.  The MER design is roughly the size of golf cart while the Curiosity rover is the size of sports utility vehicle.  In terms of capabilities, size matters.  Future rovers based on the MER design cannot replicate the full range of measurements the Curiosity and ExoMars rovers will.

Examples of a mineralogical map of a rock sample create from a prototype next generation multispectral microscopic imager proposed for future rovers (see this abstract).  Other instruments could measure the composition of each mineral assemblage in this sample (see this abstract).

In reading over the abstracts for the talks, however, I was surprised at the range of possibilities for upgrading the basic MER design to carry out sophisticated new investigations.  For example, a major upgrade discussed in two talks would be to the contact instruments that are placed against rocks by the robotic arm.  Where the current rovers carry a panchromatic (black and white) microscopic imager, future rovers could carry multispectral microscopic imagers that would take spectra of individual grains for composition analysis.  Where the current MER instruments record average composition across each measurement location (a few centimeters across if I remember correctly), the next generation of instruments would measure the composition of individual grains within rocks.  (In techno-speak, the instrument would use a microscopic laser to enable Raman spectroscopy, Laser Induced Breakdown Spectroscopy (LIBS) and fluorescence spectroscopy with measurements at the scale of 1-5 microns. The combination will provide both elemental and mineralogic composition.  While the abstract doesn’t mention one way or another about detecting organic molecules, other Raman spectrometers I’ve seen discussed would.  See this abstract for details.)  To use a crude analogy, these instruments compared to those on Spirit and Opportunity would be like going from black and white analog television to full color, 3D, 1080p high definition television.

The big upgrades to the MER design, though, would come from attaching new packages to the exterior of the rover.   The Curiosity rover in route to Mars for a landing this August also has cameras and contact instruments, but its major instrument advancements comes from sophisticated chemistry laboratories within the rover.  The MER design lacks room for instruments inside its body, but two talks will discuss packages attached to the exterior. 

One talk will propose a mission (see this abstract) that would carry an advanced laboratory that would conduct sophisticated compositional analysis and organic characterization using a combined a high-resolution mass spectrometer (HRMS) to analyze biotic and abiotic chemistry as well as Raman spectroscopy and Laser Induced Breakdown Spectroscopy for mineralogical and elemental composition measurements.  These capabilities would be similar to some of those that will be done by the Curiosity and ExoMars rovers (although sometimes with different combinations of instruments than these). 

A completely new capability in this instrument package not found in the Curiosity or ExoMars instruments suites would date samples to ~±50 million years (specifically by measuring ratios of the elements rubidium-strontium and potassium-argon.)  A major goal for returning samples to Earth is to establish firm dates (plus or minus a few tens of millions of years) for key events in Martian history.  If this could be done with a future rover, this would be a huge advance for the scientific understanding of Mars at a tiny fraction of the cost of returning samples to Earth

Sample return isn’t forgotten for the proposed MER class rovers.  Two talks will focus on bolting a sample return caching system to the exterior of the rover.  A coring drill would collect around 35 sample cores that would be deposited in a canister ready for collection by a subsequent mission for return to Earth.  The rover would also carry multispectral cameras, a remote sensing spectrometer, and sophisticated contact composition instruments to aid in sample selection.

While these talks will propose reusing the basic MER design, at least one key upgrade will be done.  The Spirit and Opportunity rovers used ballistic, unguided entry and descent that resulted in large landing ellipses.  As a result, many interesting sites, such as Curiosity’s Gale Crater site, had to be ruled out because the large ellipses contained rough terrain.  Curiosity will use guided entry and descent to substantially reduce the size of the landing ellipse.  Future MER-class missions would be upgraded to also use guided entry and descent allowing them to land at many more geologically interesting sites than were available for Spirit and Opportunity.

Beyond this upgrade, the rover design could also be upgraded in many small ways.  One talk mentions options for upgrades including advanced electronics to increase computational capabilities, higher efficiency solar cells, and upgraded telecommunications components.

While the instrument, entry and descent, and other upgrades promise exciting new capabilities, it’s important to remember that these would still be small, solar powered rovers that use airbags for landing.  They will lack the range of capabilities and driving distance of the Curiosity rover.  There are no free lunches in planetary exploration.  MER-class missions with price tags around $700M will not replace Curiosity with its price tag around $2.5B.  What is exciting is that so much could be done with upgrades to the basic design of a proven small rover   Imagine even two to three upgraded MER missions in the 2020s.