Lots of Tidbits

This blog entry will be different than most with lots of tidbits covering a wide array of topics, primarily from recent meetings for the Decadal Survey in progress.

The first tidbits come from a SpaceNews article on the joint ESA-NASA exploration program that would the two agencies programs. On Oct. 7 and 8, ESA's ruling council will receive a formal recommendation from ESA's Director-General to merge the two programs. Approval of the joint program apparently is not assured because of objections to redefining ESA's ExoMars mission. However, if the merged program is not approved, it is not clear that ExoMars can fit within the budget the member states are willing to fund. If the joint program is not approved, then NASA will try to do the Trace Gas Orbiter (which will track down amounts and sources of ephemeral gases such as methane) within a ~$450M budget (which would make it Scout/Discovery mission class). Also see tidbits below for more on the ExoMars rover and the Trace Gas Orbiter. Source: U.S., Europe Making Progress on Joint Mars Exploration Plan

The rest of the tidbits come from the Decadal Survey in progress. Five panels have been formed that will set priorities for missions within their respective areas of outer planet Satellites, Giant Planets, Inner Planets (including Earth's moon but excluding Mars), Primitive Bodies (comets, asteroids, trans-Neptunian objects, etc.), and Mars. These panels met separately over the course of August and early September. All have posted extensive notes from the meetings (but no presentations) except the Primitive Bodies panel. The focus of the notes varies from minimal coverage of the presentations and extensive coverage of the discussions to the reverse. Often, the most interesting tidbits come from the discussions. The notes usually don't make it clear whether the discussion points represented the views of one person, the consensus of the room, or something in between. So take that into account in reading these tidbits. Also, the notes from the four meetings run to dozens of pages; I'm only pulling out highlights here.

All of the notes can be found at the Decadal Survey website. There are not unique URLs for the notes, but you can find them by scrolling down the page to 'Past Meetings.' The Decadal Survey website is: http://sites.nationalacademies.org/SSB/CurrentProjects/ssb_052412

Juicy Tidbit: "The [ExoMars] mission team is quite interested in using the MSL Sky Crane system, due to its small landing error ellipse (15km ellipse vs. 75km with older system) and ability to land a large payload. However, the current plan is to fit two rovers on a pallet (MAX-C [a NASA rover] type + ExoMars), and this has not been studied. Additionally, if two rovers are going to be delivered to the same place, then we need to make sure that (1) We have compelling reasons (can do rover-to-rover imaging, MAX-C can cache subsurface samples collected by ExoMars), (2) These rovers have complementary and not overlapping capabilities, (3) We do not compromise the science objectives of either rover." However, "We also need to consider what happens if only one rover can be landed in 2018. ESA interest is very strongly committed to Exo-Mars and collaboration with NASA on TGM is tied to assistance with Exo-Mars. Currently, we cannot accommodate two rovers in MSL-type heatshield envelope." Source: Mars Panel notes

Decadal Survey Process

This Decadal Survey will place a heavy emphasis on doing high quality cost assessments of 10-15 missions that address the highest priority science goals. Substantial money has been set aside (~$1.5M per panel to be divided between the highest priority concepts selected by each panel). A substantial portion of each meeting was devoted to presentations by JPL, John Hopkin's Advanced Physics Lab (APL, which has developed several successful planetary missions), and NASA's Goddard Spaceflight Center on the capabilities of those institutions to carry out the definition of the mission concepts. The formal cost assessments will come from an independent company.

The total budget for planetary missions in the coming decade will be ~$12B. However, the budget the Decadal Survey can prioritize will be less because already approved missions for the next decade are untouchable. The latter group would include the already approved Juno, Mars MAVEN, Lunar GRACE, and Mars Science Laboratory (Curiosity). By the time the process completes in a couple of years, the Mars Trace Gas Orbiter, the Jupiter Europa Orbiter, a new Discovery mission, and a new New Frontiers mission may also be on the already approved list. The Survey can, however, have influence into the following decade by prioritizing technology development for missions in the following decade. (Missions with ready to use technology have a much better chance of approval than missions that require substantial technology development as was witnessed in selection of Jupiter-Europa as the destination of the next outer planets mission over Saturn-Titan-Enceladus.) Source: Inner Planets panel.

Results of the Previous Decadal Survey

The previous Decadal Survey had identified a list of unprioritized candidate New Frontiers missions, and the list was expanded in a mid-decade review. "An overview of the New Frontiers mission selection process was provided, and it was noted that five more missions had been added to the New Frontiers list of possible missions, but that they were not prioritized. It was noted that the primary decision mechanism had become cost and Technical Readiness Level (TRL), rather than the underlying science goals." Source: Inner Planets panel. [I would not be surprised if the same held true for Discovery mission selection, also.]

The Juno Jupiter orbiter was specified in the previous Decadal Survey as an orbiter and an atmospheric probe. The reason for the dropping of the probe illustrates the importance of technology development: "- The “P” in JPOP (the concept mission that is planned to fly as Juno) is for probe; probe is not in the technology list because the technology to make the proposed probes was assumed to be available. In reality the technology was “lost” when the heat shield company that made the Galileo probe heat shield closed. Had probe technology been explicitly prioritized, perhaps Juno would still have probes. The lesson is: for every mission proposed, the technology should be known or in the prioritized list of new technology. Otherwise the technology may not be developed and the mission will not fly. Considerations should also be made for technologies necessary for future missions, even if they are further in the future than the next 10 years." Source: Giant Planets Panel

Mars Panel

The specificity of the proposed Mars program after MSL (2011) and MAVEN (2013) is much more mature than for the other panels. The proposed missions and costs quoted in the notes are:
2016: Trace Gas Orbiter (TGO) with costs ranging from ~$450M (per the SpaceNews article) to $750M with an instrument suite consisting of a "solar occultation spectrometer, sub-millimeter spectrometer, WA camera, thermal-IR spectrometer, and high-res camera." Adding data relay capabilities to TGO to support rovers takes the mission out of the New Frontiers class (~$650M). [It's not clear from the notes whether the $750M includes relay capabilities (my understanding from past presentations) or if relay capabilities pushes costs further toward $1B.]
2018: ESA Exo-Mars
2018: NASA Mars Astrobiology Explorer-Cacher ($1.5 - 2.0B) that would both carry out scientific studies of surface material and collect and store samples for possible return to Earth by a future sample return mission.
2020: A network of geophysical landers with prices for a single station in the $450M range, three stations in the $650M range, and four is "substantially harder" [I've seen $1-1.2B in previous presentations for a four lander mission]. A single mission can prove the technology and set bounds on Mars' seismology, but at least 2 and really 3 are needed to determine the source location and four stations (three on one side of the planet and the fourth on the opposite side) to really explore the internals of the planet.
2020's: Sample return (assuming substantial investments in technology development in the 2010s).

Put together, the 2010's Mars program, excluding MSL and MAVEN is in the range of $3.5 - $4B.


Giant Planets Panel

Except for the Jupiter-Europa orbiter (for which the study of Jupiter itself will not be a priority for instrument selection), the priorities for this panel are still to be set. Concepts for a Neptune flyby (the Argo mission, which would also fly by a number of other worlds), a Uranus orbiter, and atmospheric probes of the outer planets were presented. The order of priority for atmospheric probe targets is Saturn, Neptune, Jupiter, and finally Uranus. Existing heat shield materials for Mars and Saturn are too weak to be used for entry into a giant planet's atmosphere. [The notes did not address the question of whether the shield material used for the StarDust Earth re-entry would work for some of the gas giants.] Their remains sufficient material from the Galileo mission for two Galileo class probes, but the facilities to test heat shields has been disassembled.


Satellites Panel

"There was consensus to give more attention to flyby missions gathering valuable science while also fitting within a New Frontiers (NF) cost cap. The 2003 Survey gave little attention to flybys due to the impression that the “era of flybys” was over. MESSENGER has shown that new technology makes flybys effective at gathering large amounts of high-quality data." [The notes don't say whether these would be flybys from a flyby craft a la New Horizons and Argo or flybys of moons by an craft in orbit around a gas giant.]

"In their deliberations, OPAG has found that limiting mission classes to Discovery, NF and Flagship handicaps outer solar system exploration. Opportunities to advance science on a NF budget are limited in the outer solar system and Flagship missions are rare. They encouraged NASA to develop a “small Flagship” or enhanced NF class of mission that would fly more frequently than current Flagship missions. An approximate budget of $1.2B per mission would be expected."

"Several questions probed the possibility of breaking up a Flagship mission of three components into a mix of NF missions or a NF mission and a Flagship mission. This would reduce and amortize the cost over time and simplify the mission. The lake lander and orbiter could both fly independently, but the balloon needs the orbiter for data relay. The imager and radar subsurface profiler have such high data rates that direct-to-Earth communications are unrealistic. It would be desirable for the orbiter and lander to work in concert to provide critical context, but is not necessary, particularly for seasonally unchanging areas."

"During the nominal mission, TiME (a probe that would float on a Titan sea) should drift close enough to shore to be able to image the surrounding land. Cassini radar imagery indicates very low wave activity, but prevailing winds should push the spacecraft a long distance."

In addition to the missions mentioned above, there were presentations on the Jupiter Europa Orbiter, the Io Volcanic Observer Mission, a Uranus orbiter, and the Argo Triton flyby.


Inner Planets Panel

"The International Lunar Network (ILN) is an initiative by nine space agencies to achieve network science at the Moon. NASA involvement in lunar network science has been remanded to the decadal survey for prioritization. Passive and active geophysical experiments from 2 or 4 landers (to act as “anchor nodes” for the ILN) are proposed to determine the interior structure and composition of the Moon. Current plans are for a 2018 launch and 6 years of continuous operation. The spacecraft architecture concept is mature, and the same design could be morphed into another mission. The current design falls in to the New Frontiers cost bracket."

"The three most important Venus missions in order of priority are: Venus In-Situ Explorer [an atmospheric probe and lander], Venus Atmospheric Explorer [a balloon] and Venus Geophysical Satellite [that would enhance mapping of the surface from orbit]"
There were also presentations on a 2020s Venus flagship mission (technology development is needed in the 2010s to meet this launch date) and on Mercury exploration beyond MESSENGER where an extended MESSENGER mission will be asked for and ESA will launch a sophisticated orbiter to arrive late in the decade.