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NASA announces five Discovery proposals selected for further study

Posted by Casey Dreier and Emily Lakdawalla

30-09-2015 15:39 CDT

Topics: mission status, Future Mission Concepts

Update 2015-10-01: NASA may select two of the five Discovery proposals undergoing further study listed in this post. It was suggested that NASA may stagger the development of the two missions so one ramps up in funding needs as the other ramps down, but so far no further details have been provided. The thinking behind this could be to jumpstart the Discovery mission frequency back to a healthier rate. Any announcement of final selections will come in September of 2016. --cjd

NASA announced the first-round selections for its next Discovery mission today. A total of five planetary mission concepts -- three targeted at asteroids, two at Venus -- will move to the next stage of the competition: a year-long process of detailed hardware design, cost analysis, and science planning. Next year, NASA will choose one of these mission concepts to launch no later than 2021.

Discovery is the low-cost planetary mission program managed by NASA’s Planetary Science Division. Every few years, NASA puts up a pot of money (capped at around $500 million, not including the costs of launch or operation) and the scientific community proposes missions to anywhere in the solar system that can fit within this cost cap. Proposals are led by a single Principal Investigator, or PI, that assembles a hand-picked team to attack a specific scientific unknown. Past Discovery missions include Dawn at Vesta and Ceres, the exoplanet hunter Kepler, and MESSENGER at Mercury. InSight, a geological field station on Mars, is the current Discovery mission and will launch in March of 2016.

This year, 28 proposals were submitted for destinations around the solar system. Of the five selected today for further study, only one perhaps two will actually fly. If that seems dispiriting, you’re not alone. The Discovery program was supposed provide a flight opportunity every two years, but ongoing budget cuts to NASA’s Planetary Science Division has slowed this to roughly one opportunity every five years. At this rate, a lot of great missions will never make it to space.

But let’s focus on the five finalists, all of which would deliver exciting science.

Psyche: Proposed Discovery-class mission to a metallic asteroid

Psyche: Proposed Discovery-class mission to a metallic asteroid

Three of the downselected missions aim for asteroids, but the missions are quite different:

Psyche, led by Lindy Elkins-Tanton of Arizona State University, would rendezvous with a single asteroid, (16) Psyche, a 213-kilometer-diameter object located in the outer part of the main asteroid belt. Astronomers think that Psyche is a metal asteroid based on its high radar reflectivity and high density. Did Psyche form with its metal surface, or did an ancient hit-and-run collision strip it of its mantle? If the former, we'd see a completely different kind of puzzle piece from the formation of the solar system; if the latter, we'd get to peer into the core of a planetary body. Either way, it'd be a new kind of world.

NEOCam, led by Amy Mainzer of the Jet Propulsion Laboratory, would hunt for undiscovered asteroids in the space close to Earth. Building on the success of Mainzer's NeoWISE asteroid survey mission, it would survey the sky in infrared wavelengths from a position between the Sun and Earth (the Sun-Earth L1 point). Earth-based surveys have successfully reduced our risk from near-Earth asteroids by discovering most of the larger potentially hazardous asteroids, but there is still a fair amount of space that's difficult to survey, where asteroids lurk in sky positions close to the Sun as seen from Earth. If NEOCam lasts long enough, it could find almost all of the remaining potentially hazardous objects. Not to mention that its surveys would catch approximately one million main-belt asteroids and discover potential future targets for in-situ exploration -- maybe even human exploration. NEOCam would be popular in the amateur community, promising extremely rapid archival data release, within two weeks of receipt on Earth, with no proprietary period (p. 16 of this presentation).

Lucy, led by Hal Levison of the Southwest Research Institute, would perform a reconnaissance mission to three Trojan asteroids, at least one of which is binary, using versions of instruments developed for New Horizons. The likely asteroids would be (3548) Eurybates, (21900) 1999 VQ10, (11351) 1997 TS25, and the binary (617) Patroclus | Menoetius. It would also visit a main-belt asteroid (1981 EQ5) on the way. The Trojan asteroids are a very large population -- there may be as many Trojans as there are main-belt asteroids! -- which swarm along Jupiter's orbit in the leading and trailing Lagrangian points. Models of the solar system's formation suggest that many Trojans originated in the Kuiper belt; their very dark surfaces hint at compositions rich in the organic materials that coat Kuiper belt worlds. So a mission to Trojans could tell us about a much more distant region of the solar system.

The other two missions would travel to Venus, a planet that has not seen a NASA spacecraft since Magellan entered its atmosphere in 1994. Venus has been a difficult planet to study; its opaque clouds and corrosive, hot, high-pressure atmosphere act like a force field to keep spacecraft away from its intriguing surface. Magellan gave us a radar image map of the globe at 75-meter resolution and topography at 4-kilometer resolution, but that data set left us with more questions than we had when Magellan arrived.

VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy), led by Sue Smrekar of the Jet Propulsion Laboratory, would fly a modern, shorter-wavelength radar instrument to map Venus again at much higher resolution over the course of three Venus years. VERITAS would produce a global digital elevation model for Venus, with spatial resolution of 250 meters and elevation accuracy of 5 meters.

DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging), led by Lori Glaze of the Goddard Spaceflight Center, is a Venus descent craft about which there is very little information on the Internet. According to the NASA release, "DAVINCI would study the chemical composition of Venus’ atmosphere during a 63-minute descent. It would answer scientific questions that have been considered high priorities for many years, such as whether there are volcanoes active today on the surface of Venus and how the surface interacts with the atmosphere of the planet."

With so many great missions to choose from, the question naturally arises: can’t NASA build more than one? The answer, as with many questions about NASA, comes down to money. There are no physical restrictions preventing NASA from building two Discovery missions at the same time, but that effectively doubles the money needed during the late 2010s—a time when the Mars 2020 rover project will peak in its funding needs and when the Europa Clipper will be ramping up its development. Assuming NASA wants to start another New Frontiers mission in the meantime (a beefier version of the Discovery mission program), it’s hard to see any realistic scenario that could encompass the addition of an extra Discovery mission.

That said, you never know what can happen with a supportive Congress and a new Presidential Administration. It never hurts to keep reminding them that their constituents love exploring the solar system.

See other posts from September 2015


Or read more blog entries about: mission status, Future Mission Concepts


Gregk: 09/30/2015 03:50 CDT

I'm not in love with any of these to be honest, but I'm sure I'll come around.

ethanol: 09/30/2015 04:59 CDT

For me it's between Psyche and Lucy, when possible Discovery class missions are well suited for initial characterization of unknown bodies, and we've never seen metallic asteroids or trojans close up.

Mewo: 09/30/2015 05:10 CDT

The Psyche mission, to me, has stood head and shoulders above any of the others since the beginning. I'm glad to see it's made the shortlist. I will be as excited to see this metal world as I was to see Pluto and Ceres.

Atom: 09/30/2015 06:06 CDT

I would hope a mission gets approved for Venus in the next two rounds of competition, the current Discovery and the next New Frontiers. I would like to see Vertias since it would deliver a needed improvement in the available resolution for Venus, much as MRO has done for Mars. Divinci science could be achieved with the Sage New Frontiers proposal, if chosen. I also like Psyche but am disappointed it will only visit a single asteroid. My guess is that NASA will choose Neo Cam since the political pressure to find every threatening asteroid is paramount, and it will not miss this opportunity.

Arbitrary: 09/30/2015 07:34 CDT

A stripped of core of a planetoid would be a fantastic target! And there might be one out there. It is easier to travel to other stars than to dig down to the core of what we have between our feet. And the planetary core is scientifically highly interesting for understanding planet formation and the magnetic field and what not. But why is 16 Psyche popularly believed to be such a thing? According to Wikipedia its density is 6.73 ± 3.05 g/cm³. That of Earth is 5.5. Psyche has a huge error bar there. I don't think it is worth to bet a mission on it until it has been established that it truly is a very high density asteroid.

Arbitrary: 09/30/2015 07:47 CDT

Is topography really the priority for Venus science? Shouldn't seismic or atmospheric science be on the top of the list instead? (And I hate it when I see "of" instead of "off" as in my own comment above. I blame my typing fingertips for being faster than my brain.)

ReaperX: 09/30/2015 07:58 CDT

One of the basic rules of political lobbying is that you have to ask for the full loaf to get half a loaf - or perhaps even a quarter. I don't understand why the Society's lobbying demands are so modest and pre-compromised. It's a recipe for failure. The society wants planetary exploration to be restored to $1.5b per year, the bare minimum for a viable program. Asking for the minimum means that we'll get less than the minimum, and that's what we've been getting. I don't want $1.5b per year spent on planetary exploration. I want $3b per year. I want enough to launch a new Flagship class mission every 2 years, with enough left to have a fleet of Discovery and New Frontiers missions at any given time. The money for that exists. An extra $1.5b is a drop in the bucket, a mere rounding error in the federal discretionary budget, and in any event, that investment would more than pay for itself in jobs created. If we really believe that planetary exploration is such an amazing value, then we need to make that case, and ask for what we REALLY want, not for what we think we might just barely get. Politely asking for scraps from the table is a self-defeating lobbying strategy.

lukemeister: 09/30/2015 10:45 CDT

Arbitrary: Psyche is believed to be metal from radar observations and spectra more than from density. Most recent density I could find is 3.36 ± 1.16 g cm^3.

Paul McCarthy: 09/30/2015 11:32 CDT

Disappointing. The searches for life and earth-like planets are the obvious, screaming, elephants in the room these days. $500 million is a huge amount out of a very constrained budget, to answer the much lesser questions proposed by these missions. If I recall correctly, Van Kane mentioned some other Discovery-class candidates that would have contributed to addressing the bigger questions. Honestly, how will the most ardent fan of these five candidates rate their potential yield compared to, say, Kepler??? 1/100? Be honest. No doubt the clue is in Casey and Emily's "... discover potential future targets for in-situ exploration -- maybe even human exploration", re one of the asteroid missions. This is the one that will be selected -- NASA desperately scrambling for any shred of a toehold that can potentially push the human spaceflight agenda (make some use of all those underemployed assets), even as technological and budgetary trends make these fantasies more redundant. It seems that ESA (eg the chirality experiment on Philae), India (the methane experiment on MOM) and China (eg funding the SKA telescope) have more perceptive views on where the big prize(s) are now (considering their rapid ascents from nowhere in this race). So it may well be that the US has the gleaming prizes snatched from it, as its scientists are trumped by fantasies of human exploration, due to its more media-dominant, human-celebrity-focused culture!

Goldor0ck: 10/01/2015 03:13 CDT

Frankly, these denote a lack of ambition. Now, considering the worldwide interest raised by New Horizons discovering a set of new worlds, I'd say that only Psyche could have some interest for the layperson, maybe also NeoCam by finding a target for Bruce Willis...

Anonymous: 10/01/2015 04:24 CDT

The NeoCam proposal seems very like that of the B612 sentinel proposal - I wonder why the sentinel team didn't apply. As science its not the most interesting proposal, but in terms of cost effectiveness for mitigating a disaster (city wipeout) this seems a no brainer.

Enzo: 10/01/2015 05:54 CDT

@Anonymous NASA had a partnership with the Sentinel team and they just dropped it : Maybe NeoCam is the potential winner.

Jonathan Ursin: 10/01/2015 11:39 CDT

I'm a fan of Davinci, that would be my pick of the litter. However, I'd rather see more missions looking for life in the solar system, maybe a mission to Enceladus?

spekny: 10/01/2015 12:58 CDT

I was most excited for the Enceladus Life Finder proposal. But I can't say that its exclusion was a mistake because I am not privy to the technical details of the review. (Maybe its science objectives were too ambitious for the proposed budget and instruments, or maybe it wasn't ready from an engineering standpoint.) Question for Casey: How transparent is this selection process? What else can we learn -- possibly through FOIA requests -- about the scores awarded by the panel?

Rikaishi: 10/02/2015 01:04 CDT

I would love to see an airborne rover for Venus that can take measurements from within its atmosphere. Probably from a small blimp-type platform.

Rei: 10/02/2015 08:40 CDT

"There are no physical restrictions preventing NASA from building two Discovery missions at the same time, but that effectively doubles the money needed during the late 2010s—a time when the Mars 2020 rover project will peak in its funding needs and when the Europa Clipper will be ramping up its development." As usual, NASA's Mars obsession strips the life out of the potential to explore the rest of our solar system. But hey, we just found the shocking discovery of "water" (*cough*mildly damp rocket fuel*cough*) on Mars for something like the 23rd time now.... All of these are fascinating missions, each one IMHO at least as worthy as the entire Mars 2020 Budget-Eater. It's a shame we'll only get to see one. But then again, at least I'll be happy with whichever one gets chosen. :)

Rei: 10/02/2015 09:03 CDT

That said, I do think I'd be a bit disappointed if NeoCam was chosen. There's lots of upcoming survey projects and I'm not sure why exactly NeoCam is needed in particular. For example, LSST should hit first light in 2019, first science in 2021, and full operations in 2022. NeoCam says that they'll pick up 2/3rds of the >140m NEOs, but LSST is supposed to pick up 80-90% of them as its baseline and they think they should be able to get to well over 90% after process optimization. And there's lots of other reasons to go with LSST over NeoCam... not just because it's already under construction, either. It's supposed to, for example, find practically all of the 100km+ KBOs, of which today we've only discovered about 1%. Maybe even shed light on what's perturbing the Sednoids. I'd also be more excited about a Venus balloon than a Venus orbiter or parachute-descent. DaVinci just seems to be a refined Venera mission, while Veritas just seems to be a refined Magellan. Something "new" would be more interesting, IMHO. Not that they're not good, useful mission concepts, mind you...

Arbitrary: 10/02/2015 10:28 CDT

@lukemeister But the density of iron is about 7, twice that of your number for Psyche. So how could it be a remnant of a protoplanetary core? I wish it was true, it would be fantastic, but it doesn't seem to be well supported enough to bet a mission on it.

lukemeister: 10/02/2015 06:10 CDT

Hi @Arbitrary - I believe the thinking is that the real density is probably about 4 g/cm^3 and there's about 50% porosity. Again, I think's more the radar that points toward a mostly metallic composition. I don't know where the "90% metal" I've seen quoted comes from, though.

Torbjörn Larsson: 10/04/2015 06:36 CDT

I join speakny's lament. Fundamental science can always be had, but astrobiology is an exciting question. The Enceladus Life Finder and, yes, the Venus or Psyche missions that contribute to understanding Earth, would be good choices if they can be had. @Rei: NASA isn't obsessed with Mars, it is a desire of the Decadal Survey scientists, i.e. the whole community. And the recent discovery of a water cycle (Curiosity) and liquid water flowing at the surface (MRO) are both firsts, and show that ExoMars drill is the right experiment as there can be life and/or fossils 2 m down. Why is successful science ("like the 23rd" constraint on martian water) so often criticized for its success!? I would be overjoyed to see this constraint progress anywhere. (It reminds of Hubble and Kepler successes.)

Red: 10/11/2015 04:17 CDT

The only missions I hoped for were the ones geared for the moons of Mars, in part since NASA seems to favor visiting Phobos so a preliminary visit seemed sensible. Regardless though, these choices are unexpectedly interesting. Either of the Venus missions are overdue with a large void in visits to the evil twin of Earth well warranted. While any of the asteroid missions would serve a great purpose, I'd hope Lucy to the Trojans wins out since they might be a "missing link" between asteroids and comets. IMO, I'd wish for either Venusian mission as a first choice and Lucy as a second, moreso if two Discovery missions get pulled.

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