Two Mars Missions Are Gutted Despite Near-Record Funding for Planetary Science

The President's Budget Request (PBR) for NASA's next fiscal year was released on 10 February. And while the $3 billion increase for the lunar return effort garnered headlines, the PBR touches every program within NASA's expansive portfolio, including planetary science, an area of particular interest to The Planetary Society.

Overall, NASA's Planetary Science Division fares well in the FY 2021 budget request, with a few significant caveats. The promised start of a planetary defense mission to find and characterize hazardous near-Earth objects failed to materialize in the proposal. And 2 productive Mars missions—Mars Science Laboratory (Curiosity) and Mars Odyssey—face steep cuts that would dramatically reduce the quantity and quality of science data returned by the rover and functionally end the Odyssey mission.

The Planetary Science Division

NASA's Planetary Science Division is responsible for building and operating all robotic missions for destinations in the solar system that aren't Earth or the Sun. It also provides most of the grant funding for planetary scientists and their students in the United States.

The FY 2021 request proposes $2.66 billion for the Planetary Science Division, a 2% decrease from the congressionally-enacted amount in 2020. After years of significant growth, the FY 2021 budget request effectively levels off funding for planetary science, albeit at near-record highs.

The consistent growth in planetary science funding over the past few years has allowed NASA to rebuild its planetary program significant cuts canceled and delayed a slew of missions in the early 2010s.

The Planetary Science Division manages 8 major program lines and the FY 2021 request proposes to decrease most of them—though generally due to diminishing resource needs for spacecraft projects reaching the end of their development cycles. The notable exception is the Lunar Discovery and Exploration program, which supports the Administration's priorities at the Moon and is proposed to grow by more than 50%.

Planetary Science Division funding by major program. All values in millions of dollars. Note that FY 2020 amounts for Mars Exploration, Lunar Exploration, Research, and Radioisotope Power are estimates and may change somewhat based on programmatic needs during the year.

Discovery funds frequent small planetary missions with budgets of $500 million or less. Two spacecraft are currently under development and ramping down from their peak funding needs: Lucy, scheduled to launch in 2021, and Psyche, scheduled for 2022. The budget projects support for 2 future missions to be selected in 2021.

New Frontiers funds mid-size (about $1 billion) planetary missions. Dragonfly, announced last year as the latest New Frontiers mission, is fully funded and scheduled to launch in 2026 to Titan. It projects lower funding for OSIRIS-REx operations after the spacecraft completes its sampling at Bennu this year.

The Mars Exploration Program funds the flagship Mars 2020 rover mission and all but one of the operating missions—3 orbiters and Curiosity—at the Red Planet. (The InSight Mars lander is a Discovery mission). The 2021 budget begins formulation of a Mars Sample Return mission to collect and launch to Mars orbit the samples prepared by the Mars 2020 rover. This is a major step toward sample return, the top priority of the Mars science community.

Although the proposed 3 percent cut for the Mars Exploration Program appears small overall, it falls disproportionately on 3 operating missions: Mars Science Laboratory, which would see a 20 percent drop in operations funding that would decimate its science productivity; Mars Odyssey faces a 92% cut, effectively ending the mission; and the U.S. contribution to ESA's Mars Express is defunded completely.

The cuts are surprising. Just last year, both the Mars Science Laboratory and Odyssey projects underwent independent reviews of proposed 3-year mission extensions. Both proposals were rated as "excellent" for their potential science return, and cost relatively little compared to their original development costs. Mars Science Laboratory needs $57 million per year to maintain full operations; Odyssey needs a mere $12.2 million. The total savings achieved by these cuts—$21.7 million—represents a mere 0.85% of the total Planetary Science Division budget.

It's hard to understand the motive behind these cuts. The Planetary Society encourages Congress to restore these funds in order to maintain the scientific productivity and generate the highest possible return on investment for the U.S. taxpayer for both missions.

Outer Planets and Ocean Worlds manages the Europa Clipper project and NASA instrument contributions to ESA's JUICE mission to Jupiter. Europa Clipper is currently stuck in a tug-of-war between the Administration and Congress on how it will launch to Jupiter. The White House insists it should use a commercial launch vehicle. Congress, on the other hand, has mandated that the project use the powerful—but expensive and as yet unproven—Space Launch System rocket.

This crisis is coming to a head. Because of the lead time necessary to procure a commercial rocket, Europa Clipper can no longer launch in 2023, regardless of what type of rocket it launches on. The FY 2021 budget thus delays the launch to FY 2024 and once again requests a commercial rocket. Worryingly, the PBR states that "due to ongoing development challenges with the SLS and the Artemis missions, an SLS is not expected to be available until later in the 2020s" and thus "given that NASA plans to complete development of Europa Clipper in 2023, it would be kept in storage until an SLS launch vehicle is potentially available."

Lunar Discovery and Exploration is a relatively new program within the Planetary Science Division that has grown from 0 to $451M in 3 years. It manages the novel Commercial Lunar Payload Services program (CLPS) which aims to place NASA-funded science instruments on the Moon using privately-owned lunar landers. It also funds ongoing operations of the Lunar Reconnaissance Orbiter and development of the new VIPER lunar rover. In line with the accelerated Artemis project, funding for this program has come easily, with the majority of the increases supporting additional CLPS contracts and rover development.

Planetary Defense maintains its budget at $150 million, which is high by historical standards but is not enough to start a space telescope project to search for potentially hazardous near-Earth objects (NEOs). This is despite statements by NASA officials in September of 2019 announcing the initiation of such a mission. The NEO Surveillance Mission (NEOSM) instead has funding to develop a flight-ready sensor in hopes of one day integrating it onto an actual spacecraft.

The other mission within planetary defense, the Double Asteroid Redirection Test (DART), is funded and on track for a 2021 launch to demonstrate asteroid deflection technology. 

Broad public support for planetary defense has not translated into significant funding for those activities NASA. An increase of only $46 million to Planetary Defense—to $196 million—would permit NEOSM to begin full spacecraft development with a mid-2020s launch. Securing this funding will be an advocacy priority for The Planetary Society this year.

Research and Radioisotope Power are two accounts that form the backbone of planetary exploration at NASA. Research supports the scientific workforce through competitive grants to scientists and students, maintaining the current planetary-exploration workforce and investing in its future. General planetary science research funding would enjoy a significant bump in FY 2021, offering crucial support to scientists and their students throughout the country.

Radioisotope power funds the Department of Energy's infrastructure needs to generate, store, and prepare plutonium-238 for use in power systems for planetary missions that can't depend on solar energy. Without plutonium-238, missions like Voyager, Cassini, Curiosity, and Dragonfly would not be possible.

Moving Forward

While there are a number of problems in this budget request, the big picture is a good one. This budget is strong. It supports two flagship missions, two Discovery missions, Dragonfly, a planetary defense mission, healthy science funding, and experiments with new ways of doing business in lunar exploration. Compared to just a few years ago, this budget represents a comprehensive investment in planetary exploration, the search for life, and planetary defense.

Two problems need immediate solutions. First, Congress must reverse the cuts to the Mars missions in order to preserve their science output. Every year those missions continue to operate is another year of value to the taxpayers who provided the billions of dollars required to build them. The tiny amount of money that would be saved comes at too great a cost to active scientific investigations.

Second, Congress must invest in planetary defense, specifically by funding the NEO Surveillance Mission. This mission has popular support and is endorsed by the National Academies of Science, Medicine, and Engineering as a critical asset for reducing the Earth impact hazard by detecting potentially hazardous asteroids and comets.

The problem of Europa Clipper's launch vehicle is not as urgent, but also has no clear solution. Congress mandates use of the SLS, which, while powerful, has yet to fly and requires a 5-year lead time to build. NASA's preferred launch vehicle, a commercial rocket, would impose additional travel time to Jupiter and would require the spacecraft to carry heavier Sun shielding for gravity-assist flybys of Venus. The longer this standoff lasts, the more this mission is going to cost.

The NEOSM and Mars mission problems can be solved quickly with a modest boost in funding. An additional $74.2 million—which merely returns the Planetary Science Division to its FY 2019 level—is all that is needed. The Europa Clipper issue requires a policy solution. The House's proposed NASA Authorization bill, H.R. 5666, includes language to further study the Europa Clipper launch needs, which is a step in the right direction, but a decision must be reached soon.

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