Curiosity landed inside Mars' 96-mile-wide (154 kilometers) Gale Crater in August 2012, tasked with determining if the site could ever have supported microbial life. The rover's work quickly answered that question in the affirmative, showing that Gale hosted a long-lived lake-and-stream system in the ancient past. The $2.5 billion mission also seeks to shed light on Mars' long-ago shift from a relatively warm and wet world to the cold and dry planet we know today. Gale is well suited for such inquiry; it harbors a 3.4-mile-high (5.5 km) massif called Mount Sharp, whose many rock layers preserve a long history of Martian environmental conditions. Budget cuts at Mars Curiosity has been climbing through Mount Sharp's foothills since September 2014, studying clay-rich sediments that are evidence of ancient aqueous environments. The six-wheeled rover has gotten about 1,350 feet (410 meters) above the crater floor to date — so high that it's nearing a transition zone between the clay unit and the sulfate-rich rocks above, which are evidence of a much drier Mars. But the funding situation may make exploring this new and potentially revelatory region tougher and more time-consuming than the Curiosity team had thought. The White House's 2021 federal budget request allocates just $40 million to the mission, a decrease of 20% from the rover's current funding. And that current funding is 13% less than Curiosity got in the previous year, said Curiosity project scientist Ashwin Vasavada, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
If the 2021 request is passed by Congress as-is, Curiosity's operations would have to be scaled back considerably. Running the mission with just $40 million in 2021 would leave unused about 40% of the science team's capability and 40% of the rover's power output, which comes from a radioisotope thermoelectric generator (RTG), Vasavada said. "The team feels a bit under a crisis now because of the funding situation," Vasavada said on April 17 during a meeting of NASA's Mars Exploration Program Analysis Group (MEPAG), which aids agency efforts to explore the Red Planet. "This is a big morale hit for us." In addition to the clay-sulfate boundary region, the Curiosity team wants to spend some time studying a nearby formation called the Greenheugh Pediment. Just atop Greenheugh is a ridge that may have been formed by debris-carrying liquid water that originated higher up on Mount Sharp, long after Gale's lakes dried up, Vasavada said in his MEPAG presentation. "This is just a huge climate signature that we want to be able to explore," he said. An end in 2022? Vasavada said that Greenheugh and the clay-sulfate transition zone are the mission's two major exploration objectives for the near future. But enactment of the 2021 budget request would probably force the mission team to push one of those two activities beyond 2022, he said — and such a delay might end up consigning the unlucky objective to the dustbin.
That's because Curiosity's outlook gets far more uncertain after next year. For starters, the 2021 federal budget request zeroes out the mission in 2022, projecting no money for the mission that year or in any future years. And, even if funding does eventually come through, the output of the rover's RTG — which converts to electricity the heat generated by the radioactive decay of plutonium-238 — will likely have declined enough by 2022 to start taking a significant toll on science work, Vasavada said. (Curiosity remains in good health otherwise, he stressed.) "NASA and the Mars science community have the great fortune of having this flagship rover in great shape with an experienced team, ready to further advance our study of ancient habitability," he said. "There's a window that's closing to use Curiosity because of the RTG." Not just Curiosity Vasavada isn't the only Mars mission lead with budget laments; the 2021 funding request is rough for most of the space agency's other robotic Mars probes currently in operation as well. For example, proposed cuts to the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter mission would "require a significant downsizing of the science team starting this year, this coming year, and then each year into the future," principal investigator Bruce Jakosky, of the University of Colorado Boulder's Laboratory for Atmospheric and Space Physics, said during his MEPAG talk on April 17. (Leaders of NASA's robotic Mars missions gave updates on that day.) The $2.5 million proposed cut to the Mars Reconnaissance Orbiter (MRO) in 2021 would force the venerable mission to reduce its targeted imaging observations by 50% and its radar observations by 30%, said project scientist Richard Zurek of JPL.Then there's Mars Odyssey, an orbiter that has been studying the Red Planet since 2001. The 2021 budget request allocates just $1 million to Odyssey. As a result, the mission "would have to end this calendar year — really, in the next few months," said project scientist Jeff Plaut, also of JPL, in his MEPAG presentation. All of these orbiters remain in good health, the MEPAG presenters said, and all of them provide vital communications-relay services in addition to their science work. Odyssey, for example, relays to Earth 62% of the data collected by NASA's marsquake-hunting InSight lander, which touched down in November 2018.And those communications needs are going to increase less than a year from now, when NASA's next Red Planet rover touches down. The life-hunting, sample-caching Mars 2020 rover Perseverance is scheduled to launch this July and land inside the Red Planet's Jezero Crater in February 2021.
Plaut ended his MEPAG talk by saying he hopes the Mars science community sees value in the continuation of Odyssey's mission and voices that value to decisionmakers — namely, Congress, which controls the nation's purse strings and therefore has final budgetary say. (A White House federal budget request is just that — a request — before Congress enacts it.) He found a receptive audience. One of the findings of the three-day MEPAG meeting, as determined by the steering committee and chairwoman Aileen Yingst of JPL, was an objection to the budgetary treatment of Odyssey, MRO, MAVEN and Curiosity (whose mission is officially called the Mars Science Laboratory, or MSL). "MEPAG finds that the substantial reduction of funding for the extended missions of MSL, Odyssey, MRO and MAVEN and the projected closeout of MSL in 2022 and Odyssey in 2021 are inconsistent with their high rankings by the Planetary Mission Senior Review," Yingst said on April 17, reading the finding for meeting participants. "This would result in major, perhaps unrecoverable, losses for science and does not reflect community priorities," she added.