International Collaboration

Planning for the current iteration of Mars sample return began in 2016 with high-level negotiations between NASA and ESA. During this process, the two agencies dusted off previous mission concepts and converged on a plan affordable for both agencies. This process concluded with the signing of a joint NASA/ESA Statement of Intent at the Berlin Airshow in April 2018, allowing the space agencies to begin developing the “business plan” to their respective governments.

In the following months, NASA assigned responsibilities to its various spaceflight centers, but detailed architectural studies could not begin until the FY2019 budget appropriations allocated money to the project. ESA used this time to commission 2 design studies for the Earth-return orbiter and an additional 2 design studies for the surface retrieval rover. Watzin said he was “pleased and impressed with how aggressively ESA has pursued this project”.

NASA has been rushing to make up for the delay since the FY2019 budget was approved in March. On 12 July, NASA formally approved the roles and responsibilities in the joint collaboration with ESA, essentially finalizing the overall mission structure. Two critical final budgetary steps remain. On the ESA’s side, a Ministerial Council meeting will take place on 26-28 November to approve the proposed budget for the Earth-return orbiter. On NASA’s side, its FY2020 budget requested money to finalize the mission architecture design with the goal to begin sample retrieval lander development in FY2021.

Pressure on Other Mars Missions

The scale of the project has led to some concerns among NASA’s Mars research community. The concern most frequently voiced during the plenary session and subsequent MEPAG meeting was its effect on the rest of the Mars program. NASA’s Mars fleet is aging. The two spacecraft that support all surface research by performing relay communications, Mars Odyssey and Mars Reconnaissance Orbiter, have been operating in Mars orbit for 18 years and 13 years, respectively. Odyssey is expected to run out of propellant by 2025, and the condition of Mars Reconnaissance Orbiter’s batteries could end its operations as early as the mid-2020s.

The cost of Mars sample return would likely prevent a follow-on to either of these Mars-orbiting missions until after the samples are returned to Earth in 2032. That would shunt the bulk of surface relay onto NASA’s MAVEN and ESA’s Trace Gas Orbiter, adversely affecting the research capabilities of those missions. MAVEN has completed its primary mission and Trace Gas Orbiter will complete its own at the end of 2019. Although both missions have always expected to spend significant resources performing data relay during their extended missions, both have encountered more complex environments than originally expected. A major concern voiced by the Mars community was that the need to move these missions to rover support would negatively impact these missions’ own exploration. Indeed, Trace Gas Orbiter is already handling 60% of Curiosity’s data return, according to ESA’s Jorge Vago.

There is the possibility of a Mars orbiter mission being prioritized for a future Discovery or New Frontiers mission to alleviate pressure on MAVEN and Trace Gas Orbiter. However, such an orbiter would have to compete with the rest of NASA’s science program for funding. Given NASA’s recent push towards asteroids and icy bodies with these programs, that competition is likely to be stiff. The Mars science community expressed a lot of pessimism regarding the chances of funding such missions, given the large amount of money already directed towards the Mars program and Mars sample return. Scientists with interests beyond the Mars program also fretted that a Mars orbiter mission in addition to Mars sample return would further delay exploration of other high-priority targets within the Solar System.

In addition to relay, Mars Reconnaissance Orbiter provides another surface on which landed missions depend. It carries MARCI, currently the only camera capable of providing daily weather maps of the entire surface. These maps are used to plan power budgets for solar-powered missions and scale operations accordingly. The timeline outlined above would see sample retrieval surface operations begin as Mars Reconnaissance Orbiter reaches the limits of its design life, meaning there is a strong possibility that sample retrieval would be taking place without global weather monitoring. Landing outside of the historical dust season mitigates the hazard, but this year’s dust activity shows the risks of relying on average conditions for predicting seasonal behavior. Claire Newmann (York University) pointed out that local- and regional-scale dust storms following the massive Mars year 34 dust storm (which killed Opportunity in 2018) continued well into the spring of the following Mars year, which would have adversely affected SRL’s operations had it been operating under this year’s conditions.

Failing to replace Mars Reconnaissance Orbiter’s weather monitoring capabilities would also create a gap in observations of Martian climate conditions, which have been continuous since Mars Global Surveyor’s arrival in 1997. A major research goal identified during the Ninth International Conference on Mars was forecasting Martian dust storms and predicting whether they could expand into global events. The loss of Mars Reconnaissance Orbiter’s weather mapping capabilities without a replacement mission would create a gap in Martian climatological records lasting as long as a decade.

Finally, there is some concern regarding how Mars sample return could affect the pace of Mars 2020 operations in Jezero Crater. Mars 2020 deputy project scientist Katie Stack Morgan described an aggressive pace of operations that includes the collection of 20 samples from 7 different geological units and an approximately 10-kilometer traverse from the landing site to the Jezero Crater rim by the end of the baseline mission in 2023. This pace is dictated by the arrival of the sample retrieval lander in 2028 and the desire to send Mars 2020 to collect some samples from the Midway landing site.

Midway is described as a “stretch goal” for the 2020 rover, an opportunity to see and sample a different suite of geologic materials that is available within Jezero crater. Jezero is primarily a delta environment, while the Midway site contains materials that originated deep in Mars’ crust that were excavated by the Isidis impact. If the Mars 2020 rover were to travel to Midway, it could visit two very different geological environments with one mission.

The sample retrieval lander can only land safely at either the Jezero or Midway landing sites developed for Mars 2020.The 2020 rover’s traverse to Midway is expected to take around 5 years, meaning that if it is to reach Midway in time to meet the sample return mission, Mars 2020 will need to depart Jezero by 2023. ASU’s Steve Ruff voiced his concern that attempting to make a 2023 departure date from Jezero would severely compromise the scientific goals of Mars 2020. The pace of the mission as planned dictates that Mars 2020 average one sample a month, limiting the amount of time available to evaluate the most useful sampling locations and to characterize the local environment of the samples.

JPL’s Ken Williford, another deputy project scientist for the 2020 rover, described the mission team’s approach to mitigate this issue. The rover’s operators have been participating in a series of preparation activities called ROASTT (Rover Operations Activities for Science Team Training), which spent “lots of time and effort practicing at the ambitious science goals to hit the ground running.” The first ROASST activity took place in 2018, with operators meeting to strategize for their traverse and work out the broad scale of the sampling campaign. A second ROASST activity took place this year, simulating the science campaign and giving the team a chance to practice tactical operations. A final ROASST activity is planned early next year, emphasizing sample decision-making. Ken Williford described the final ROASST activity in Kenny Rogers lyrics, saying rover scientists “gotta know when to hold ‘em.”

However, another recurring theme of the Mars conference was the inability of remote sensing to see everything at the surface. As experience with previous Mars rovers has shown, the geology on the ground has always been more complex than what has been observed from orbit. Previous experience with traverse planning during the Apollo missions also highlighted the tight constraints that highly-structured traverses place on investigating the unexpected. The geology of Jezero Crater is undoubtedly complex and there is a good chance that Mars 2020 will come across at least one unexpected discovery. These discoveries take time to understand, and the rush to position the rover for a possible traverse to Midway might prevent the mission from obtaining the data necessary to understand what the rover is seeing.

The MSR program represents a highly ambitious project, with the potential to fulfill a goal that NASA has been pursuing on and off since the 1960s. Momentum has been building for nearly two decades, and it is looking like a more reachable goal than it has in a long time. If it does proceed, will it unlock transformation in our understanding of Mars, or begin a decades-long dark age in Mars science?