As most readers are surely aware, NASA's effort to return to the Moon in recent years included the robotic precursor missions Lunar Reconnaissance Orbiter and LCROSS. These modern robotic pathfinders for HSF succeeded, but the costly Ares rockets and Orion capsule forced the elimination of the longer-term line of robotic precursor missions that was such a crucial part of the Vision for Space Exploration. NASA's proposed FY2011 change in direction called for the revival of the robotic precursor line, but this time it would scout multiple destinations, such as the Moon, NEOs, Mars, and the Martian moons, for resources and hazards to astronauts, as well as to demonstrate technologies like ISRU at those destinations. In the compromise between the Administration and Congress that allowed NASA to start the commercial crew program and to restore some technology development funding lost during the Constellation years while forcing the agency to develop the SLS and MPCV, the robotic precursor mission line was first scaled back considerably, and then lost altogether. With the prospect of budget overruns on the big projects and general downward pressure on NASA's budget, it doesn't look easy to revive the robotic precursors.
It is possible for NASA's Planetary Science program to do some robotic precursor work as a by-product of its robotic science missions, but NASA's Planetary Science budget is being cut. In this case the expensive JWST is a major cause of the budget pressure, but the expense of the proposed Planetary Science Flagship missions is not helping.
Could the situation for robotic precursor missions be any worse?
There is no doubt about it, the vital concept of robotic precursor missions for HSF has fallen on hard times. Robotic precursor missions can be quite affordable and can accomplish a lot, but it's not easy for them to thrive at NASA when the agency budget is cut while expensive NASA projects with strong political backing enjoy cost overruns and delays.
Having set this rather unpleasant stage, I'd like to offer some hope for robotic precursors. I don't think we will see a fleet of NASA robotic precursor missions fanning out across the inner solar system like we might have hoped during NASA's FY11 budget proposal, or making tracks in the lunar surface like we might have expected during the early days of the Vision for Space Exploration. It's likely that many of the robotic precursor possibilities I'll mention will not come to fruition, but we still can reasonably expect to see some progress. Here are some possible sources of such HSF robotic precursor progress:
Planetary Resources - There has been a lot of discussion of the long-term goal of Planetary Resources to mine asteroids, and also of its shorter-term prospects in selling low-cost spacecraft for astronomy and Earth imaging. However, I haven't seen nearly has much on the role this company could play in the robotic precursor field. Consider NASA's August 2010 Exploration Precursor Robotic Missions (xPRM) Point of Departure Plans (PDF) presentation, which focused on NEO robotic precursor missions. This set of missions included a NEO Telescopic Survey to identify appropriate NEOs for HSF missions. It also included several options for NEO Rendezvous missions to more fully characterize potential targets, from one spacecraft comparable to a NASA Discovery mission to study a single NEO in detail to a set of 3 or 4 small spacecraft to study several potential HSF destinations in less detail. These NASA plans don't appear to have much chance of happening in the current political and budget environment, but consider how Planetary Resources might achieve similar goals, either in the course of their own space resource assessment and development plans or by offering a low-cost way for NASA to achieve some of its robotic precursor goals should a funding wedge appear. The first Planetary Resources spacecraft is a Leo Space Telescope that can search for NEOs. The second Planetary Resources spacecraft planned is the Interceptor that could approach, study, and possible "intercept" Earth-crossing NEOs. The third generation is the Rendezvous Prospector, which could rendezvous with NEOs that are more difficult to reach and require more capable communication links. It's not too difficult to see how these generations of spacecraft could fulfill some of the robotic precursor ambitions that NASA had for NEOs, although depending on the circumstances the resulting data might not be available to certain organizations that might need it.
Google Lunar X PRIZE - The Google Lunar X PRIZE is a $30M competition intended to encourage private groups to develop mobile lunar landers. There are dozens of Google Lunar X PRIZE teams with varying goals, prospects for winning the competition, and intent to do work that would return significant robotic precursor data. I won't describe all of the teams here, but instead will just give one example of a prominent team with robotic precursor ambitions. Astrobotic intends to send an 80 kg rover, Red Rover, near the lunar equator to win the prize and to deploy 30 kg of science instruments. It then plans to send a 150 kg rover, Polaris, with 80 kg of instruments to one of the lunar pole regions to prospect for water. The intent is to continue with a series of missions.
NASA's Mars Upheaval - I have mixed feelings about the current changes in NASA's Planetary Science portfolio, and in particular with its Mars missions. On the one hand, I don't think Planetary Science is the right place for the budget ax to fall, and I don't like to see an affordable mission like the 2016 ExoMars Trace Gas Orbiter mission abandoned (at least as far as the U.S. is concerned). On the other hand, I don't think either NASA's original Mars Sample Return plan or the next-in-line Flagship mission to Europa were affordable, and the possibility of developing more affordable missions with intentional HSF participation in the robotic precursor sense is welcome. It's hard to predict what the outcome of all of this will be, and it's probably a fair bet to guess that it won't end well. In the meantime, we can see a step in the process right now at the Concepts and Approaches for Mars Exploration conference being held from June 12-14 at the Lunar and Planetary Institute. Here are some sample abstracts (all PDFs) that show some of the robotic precursor possibilities that just might emerge from the current chaos:
ICE DRAGON: A MISSION TO ADDRESS SCIENCE AND HUMAN EXPLORATION OBJECTIVES ON MARS - We present a mission concept where a SpaceX Dragon capsule lands a payload on Mars that samples ground ice to search for evidence of life, assess hazards to future human missions, and demonstrate use of Martian resources.
HUMAN EXPLORATION AND PRECURSORS: IN SITU RESOURCE UTILIZATION - This is a whole track with 9 abstracts dealing with Mars robotic precursors and ISRU.
PHOBOS AND DEIMOS SAMPLE COLLECTION & PROSPECTING MISSIONS FOR SCIENCE AND ISRU
Radiation Dosimetry From a Nanosat Lander System for Mars
Existing NASA Robotic Science Missions - Robotic science missions can accomplish HSF robotic precursor goals even though that is not really their purpose. NASA currently has a number of robotic science missions at potential early HSF destinations. Mars Odyssey and Mars Reconnaissance Orbiter are in orbit around Mars, as are NASA instruments on Europe's Mars Express. The Opportunity rover still operates on the Martian surface. Dawn is transitioning from its investigation of asteroid Vesta to soon begin its voyage to Ceres. The GRAIL spacecraft are in orbit around the Moon, and their gravity map can be expected to help with future lunar landings. The re-purposed ARTEMIS spacecraft from the THEMIS heliophysics mission are now doing lunar science from Earth-Moon Lagrange points. The best example of all is probably the Lunar Reconnaissance Orbiter, which continues to gather robotic precursor data even though it is now managed as a science mission. This just covers NASA missions, but there are international robotic science missions with robotic precursor potential, too.
Do these existing science missions offer enough robotic precursor potential for you? Probably not, but it could be a lot worse. Consider the 1980's and their huge list of robotic precursor missions and science missions with robotic precursor by-products. Yes, things can get worse than they are today.
Selected Future NASA Robotic Science Missions - Several NASA robotic science missions under development have the potential to return valuable robotic precursor information. LADEE will study lunar dust and demonstrate laser communication from lunar orbit, both of which have implications for human lunar missions. MAVEN will study the Martian upper atmosphere. Osiris-REx will study and return a sample from carbonaceous asteroid 1999 RQ36. The "RI" in "Osiris" stands for "resource identification", a clear nod to robotic precursor potential in this science mission.
Potential Future NASA Robotic Science Missions - A number of potential future NASA missions (other than those of the Mars-specific mission line I already discussed) could provide robotic precursor information. The selection for the next round in the NASA Discovery program is scheduled to be made soon. One of the three contenders is InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport), a Mars Geophysics lander mission. The Planetary Science Decadal Survey recommended that NASA consider 7 missions for 2 selections over the course of the next decade (2013-2022). These missions include Lunar South Pole-Aitken Basin Sample Return (similar to the MoonRise proposal from the final round of the last New Frontiers selection), Trojan Tour and Rendezvous (which unfortunately would take a very long time to reach the asteroids near Jupiter's Lagrange points), and Lunar Geophysical Network.
Unfortunately, proposed Planetary Science budget reductions don't just affect the Flagship proposals as has been widely reported. These reductions also greatly reduce the number of Discovery and New Frontiers missions that would be flown over the course of the next decade.
Mars Science Laboratory - I didn't mention MSL as either an existing NASA mission or a mission under development since it's no longer under development, but not yet in its primary operational phase. Curiosity will land on Mars soon. This is a major, highly capable Mars Science rover that can be expected to deliver useful robotic precursor knowledge if it succeeds in reaching operational status. There will be multiple sources of such knowledge. For example, the MEDLI (MSL Entry, Descent, and Landing Instrumentation Suite) technology demonstration on the lander heat shield will gather data about the Martian atmosphere and the performance of the landing hardware as it works. This will enable improved landing systems in the future. The RAD (Radiation Assessment Detector) is a genuine robotic precursor instrument whose main purpose is to assess radiation hazards for future astronauts on Mars.
NEOCam - In addition to selecting InSight as 1 of 3 competitors for NASA's next Discovery mission, 3 Planetary Science technology development efforts were selected by Discovery. One of these is NEOCam (PDF), an IR space telescope intended to search for Near Earth Objects. This would be useful as a robotic precursor tool, since our catalog of NEOs that are suitable destinations for early HSF missions is small.
Will all of the possible future missions I mentioned with robotic precursor potential happen? I would be surprised if most of them do. Will the NASA Science missions deliver significant robotic precursor data? That will vary on a mission by mission basis - some can be expected to deliver significant robotic precursor data, and the robotic precursor benefit of others will likely be tenuous at best. The Administration and NASA should make a stronger stand for funding a dedicated line of robotic precursor missions to the Moon, NEOs, Mars and its moons. Although a large budget would be helpful, to be productive this line would not need the type budget the Administration originally proposed for robotic precursors if it used focused, small, low-cost missions, instrument/experiment rides with other missions (such as robotic science missions), and/or lean commercial procurement strategies (data purchase, etc).