The problems facing the Mars Exploration Program identified in the report are worth quoting in full (emphasis added):
"The [Mars Exploration Program] has shifted to more expensive, large-rover missions to address scientific questions posed by orbiter missions, while simultaneously shouldering the cost of operating existing Mars spacecraft. A combination of the focus on [Mars Sample Return], the constrained budget to formulate it, and the lack of formal approval for the Fetch Rover/Mars Ascent Vehicle and Sample Return Orbiter has resulted in lack of a defined schedule and budget to implement Mars Sample Return and lack of a long- term plan besides sample return. The net effect has been two main consequences:
All Mars surface missions listed above—plus the InSight Discovery mission—rely on Mars orbital missions now in flight for a UHF relay to return data to Earth. Of all NASA orbiters with this capability, only MAVEN has been operating less than 12 years. MRO is the major relay asset, and it is aging. The lack of a new orbiter in development means that the Mars telecommunications infrastructure is not being renewed, and is subject to aging and potential failure.
[There have been a] variety of new Mars discoveries since the publication of Visions and Voyages, including the diversity of wet environments on ancient Mars beyond the one or possibly two that will be sampled by Mars 2020, the occurrence of widespread shallow, nearly pure ice, and the possibility of modern briny flows. There are no current Mars Exploration Program plans for follow-up investigation of these or other findings, either for hypothesis-driven science that has been the hallmark of the MEP, or for assessment of resources for future human exploration."
This cuts to the heart of it. What was previously a program that could react to scientific discoveries is now functionally a single project--Mars Sample Return. But NASA is barely able to shoulder that effort, constraining itself to exploring "lean" return efforts that may eschew new science instrumentation at Mars in the 2020s.
The report also referenced budgetary analysis formed by Jason Callahan (the Society's Space Policy Adviser) and myself in our "Mars in Retrograde" paper, which demonstrated the decline of funding provided to the Mars program over the years, a reflection of its diminished priority within the agency.
Jason Callahan and Casey Dreier, The Planetary Society
Mars program funding, 2000 - 2022 (annotated)
Mars Exploration Program funding as a percentage of the space science budget and NASA's total budget.
In response to these and other findings, the report recommends that:
"NASA should develop a comprehensive [Mars Exploration Program] architecture, strategic plan, management structure, partnerships (including commercial partnerships), and budget that address the science goals for Mars exploration"
Due to active support from The Planetary Society and our members, Congress provided an additional $75 million for technology development for the Mars program last year, though NASA has still not requested a "new start" for the next phase of the sample return campaign.
Speaking of sample return, the report also examined NASA's progress toward addressing the top recommendation of the decadal survey: a caching rover to start a sample return campaign from Mars. The Mars 2020 rover is deemed to fully meet those recommendations by including a full suite of in-situ scientific instrumentation and a sample caching and preparation system at ⅔ the cost of the original decadal estimate.
As for the follow-on mission necessary to retrieve and launch those samples, NASA has yet to commit to a mission. Dr. Thomas Zurbuchen, the Associate Administrator of NASA's Science Mission Directorate, stated last year that NASA's intent is to pursue the next phase of sample return no earlier than 2026, using a "lean" architecture that focuses on returning samples and engaging international partners in the effort.
The report blesses this effort, recommending that:
"NASA should continue planning and begin implementation of its proposed "focused and rapid" architecture to return samples from the Mars 2020 mission to achieve the highest-priority decadal survey flagship-class science for consideration for the next decadal survey."
And finally, the report addresses one of our primary concerns: the future of telecommunications infrastructure at Mars. Or, more precisely, the lack thereof.
Mars is the only other planet (that we know of!) with a satellite communications system. NASA's ground assets, like Curiosity and Opportunity, depend on regular flyovers by science orbiters that serve to relay their data to and from Earth. The orbiters, with much larger and more powerful antennas, send data to Earth orders of magnitude faster than direct-to-Earth communication from the ground missions themselves.
But because the Mars Exploration Program is now functionally a Mars Sample Return project, no new orbiters are planned. The youngest orbiter—MAVEN—launched in 2014. Mars Odyssey launched in 2001. These missions will not last forever, though NASA is taking steps to extend their lifetimes as long as possible. The European Trace Gas Orbiter mission (launched in 2016) can also serve as a communications relay for NASA's ground missions in a pinch.
The report summarized the significance of this problem (emphasis added):
"There is a risk that ongoing and soon-to-be landed assets on Mars will be left without telecommunications support because of the aging orbiters. The Mars telecommunications relay network is marginally able in its present form to service current and planned surface missions. The system is fragile and aging. The loss of even one of the three U.S. orbiters capable of relay communications (Mars Odyssey, MRO, MAVEN) would create tactical challenges for continued operation of current and planned landed missions beyond 2021, and compromise the ability of the MEP to continue its science return...Also, despite the hardware capability, there is no plan for the European Space Agency (ESA)'s Trace Gas Orbiter (TGO) to be used as a relay asset in the immediate future."
The recommendation, however, is a little weak:
"NASA should ensure the longevity of the telecommunications infrastructure at Mars to support the science return from current and planned landed assets (e.g., MSL, Insight, ExoMars, Mars 2020), to mitigate the risks associated with the existing aging assets. This should not be accomplished by sacrificing the science being conducted by existing orbiters."
NASA is already doing this, though some science will be sacrificed by moving MAVEN into a more data-relay-friendly orbit.
NASA should immediately commit to a Mars telecommunications and high-resolution imaging orbiter to replace rapidly aging assets currently at Mars.
NASA should begin formulation of a sample retrieval rover and Mars Ascent Vehicle mission to continue the overall Mars Sample Return campaign.
NASA should formulate a follow-on strategy to the Robotic Mars Exploration Strategy, 2007-2016 document.
While we have seen significant and important progress toward sample return, the fact remains that the Mars Exploration Program is a program in name only. NASA has still not committed to a mission after the Mars 2020 rover, and launch windows to Mars occur for just a few weeks every 26 months. The considerable orbital infrastructure built up by NASA at Mars has no replacements in the pipeline. Most of the U.S. missions are operating far beyond their design lifetimes. Unless steps are taken now, there are more endings than beginnings for NASA at Mars in the next decade.