FYI: Science Policy News

FY24 Budget Outlook: NASA

DEC 21, 2023
NASA’s Science Mission Directorate is facing a constricted budget environment in fiscal year 2024 that is likely to result in delays to planned missions as well as curtailments to some missions that are currently operating. How NASA will distribute the burden is contingent on congressional decisions such as how much funding will be allocated to the flagship Mars Sample Return mission.
Will Thomas
Spencer R. Weart Director of Research in History, Policy, and Culture

NASA’s Science Mission Directorate is facing a serious funding crunch this fiscal year, with both House and Senate appropriators proposing to cut its nearly $7.8 billion budget by just over 5%. The directorate would still receive more funding than it did as recently as fiscal year 2022, but its budget would fall far short of what it needs to keep its planned missions on track. NASA has already made some project adjustments in anticipation of constrained budgets and telegraphed potential further actions, but many uncertainties will remain unresolved until Congress completes its spending legislation.

The greatest questions surround the beleaguered Mars Sample Return mission. The Senate proposal calls for slashing MSR’s budget to about one-third its current size and broaches the prospect of canceling it altogether. This budget reduction would allow most other missions to be funded at their requested levels. Conversely, the House proposal would fund MSR at the administration’s requested level while spreading its cut across the directorate, with little further direction concerning what specific programs should be curtailed.

There are also uncertainties around the Heliophysics Division’s Geospace Dynamics Constellation, a high-priority mission to study the Earth’s magnetosphere and upper atmosphere with multiple satellites. Even under the Biden administration’s proposed 6% increase in the Science Mission Directorate’s budget, GDC was in line for a delay. The House proposal for the division would leave little room to fund the mission, but the Senate proposal would explicitly protect it.

The administration’s request is detailed in NASA’s budget estimates document, and Congress’ proposals are detailed in documents assembled by House and Senate appropriators. Summary figures are collected in FYI’s Federal Science Budget Tracker.


Chart of appropriations proposals for NASA’s Science Mission Directorate.

Planetary Science

The Senate proposes to reduce the topline budget for NASA’s Planetary Science Division from $3.20 billion to $2.68 billion, whereas the House would leave the division with $3.10 billion. Excluding MSR, the remaining budget for all other planetary science activities would remain about even under the Senate proposal at around $2.38 billion, whereas under the House proposal it would drop to $2.15 billion. The administration requested $2.43 billion.

Mars Sample Return. The administration proposed to raise MSR’s annual budget from $822 million this year to $949 million, an amount that is far higher than the budget for any other Science Mission Directorate mission. A recent independent review found the mission is likely to need about that much funding for several years in a row to be ready to launch by 2030, at the earliest.

Citing concerns about MSR’s impact on other missions, the Senate proposal directs NASA to spend “not less than” $300 million on it in fiscal year 2024. It also states that if NASA cannot constrain the mission’s lifecycle cost to $5.3 billion, then “NASA is directed to either provide options to de-scope or rework MSR or face mission cancellation.” Released after the Senate proposal, the independent review projected the mission will cost NASA between $8 billion and $11 billion. Although the House proposal would spare MSR a cut, NASA has already cited the prospect of a diminished budget in directing mission staff to slow down work while the agency reevaluates the mission’s design and schedule.

Should MSR be canceled, the Senate proposes to transfer $235 million of the $300 million to the Artemis lunar exploration campaign, which is outside the Science Mission Directorate. Within the directorate, the Dragonfly mission to Saturn’s moon Titan and the Geospace Dynamics Constellation would each receive $30 million. The remaining $5 million would fund early work on a mission to Uranus, which the latest National Academies planetary science decadal survey ranked as its top priority for a flagship mission after MSR.

New Frontiers mission delays. NASA has already pushed back some planetary science missions due to budget pressures. In November, NASA decided to delay Dragonfly’s launch by one year to 2028. This past summer, the Government Accountability Office reported that Dragonfly had been courting such a delay due to being funded at a less-than-optimal level. Dragonfly is the newest mission in NASA’s New Frontiers program, which is the most expensive class of planetary science mission that is open to competitive selection. In August, NASA moved the start of the competition for the next New Frontiers mission from this year to 2026 at the earliest, again citing budgetary factors.

VERITAS. Last year, NASA also decided to put its VERITAS mission to Venus on the back burner to alleviate the overstretching of staff at the Jet Propulsion Laboratory, the NASA center that is developing missions that include VERITAS, MSR, and the flagship Europa Clipper. The move is expected to delay the launch of VERITAS from late 2027 to no earlier than 2031. However, the House proposal would push NASA to request enough funding for VERITAS to permit a launch by the end of this decade.

Priority missions. New cuts to the Planetary Science Division could result in disruptions beyond those already announced, but it would be largely up to NASA to determine what efforts would bear the burden. One project unlikely to be affected is the Europa Clipper, a spacecraft that will investigate an icy moon of Jupiter harboring a subsurface ocean. Its budget is set to decrease from $345 million to $303 million ahead of its launch in October 2024, and a failure to meet that schedule would lead to immediate cost increases. The House and Senate proposals would both provide the $210 million requested for the Near-Earth Object Surveyor telescope. A year ago, NASA pushed back that mission’s launch from 2026 to 2028.


Engineers and technicians prepare to install the high-gain antenna on the Europa Clipper spacecraft.

(NASA / JPL-Caltech)

Earth Science

The administration aimed to increase the Earth Science Division’s budget from almost $2.20 billion to $2.47 billion. However, the Senate proposal would provide a small increase to $2.22 billion, while the House proposal is for an even $2 billion.

Future satellites. A significant part of the administration’s proposed increase was for accelerating work on the next Landsat mission and a set of four missions, collectively called the Earth System Observatory, that respond to priorities in the latest National Academies decadal survey for NASA’s Earth science portfolio. A smaller portion of the increase is to begin work on smaller-scale Earth System Explorer satellites. Although the Senate proposal calls for NASA to fully fund the Earth System Observatory and Earth System Explorer programs, delaying work on these satellites is one way NASA could respond to a constrained budget, especially given that research budgets were already lower in fiscal year 2023 than in the year before.

Terra, Aqua, and Aura. Even under the administration’s request, NASA was planning to reduce funding for operations of the flagship Terra, Aqua, and Aura satellites, which are aging and beginning to stray from their orbits. The recent senior review of NASA’s operating Earth observation platforms concluded the three missions still provide high-value data, but it is unclear how much funding for them could be maintained given the constraints on the Earth Science Division’s budget.


Proposals for the Heliophysics Division’s budget diverge markedly. The administration requested to cut funding from $805 million to $751 million and the House proposes a reduction to $710 million, but the Senate seeks a level budget. The lead Senate appropriator for NASA, Sen. Jeanne Shaheen (D-NH), is a proponent of heliophysics, which is a major focus for the University of New Hampshire in her state.

Geospace Dynamics Constellation. The brunt of the administration’s proposed cut would fall on GDC, a mission recommended in the latest National Academies decadal survey for solar and space physics. NASA’s budget justification broaches a “pause” in the mission’s development so that funding could be allocated to higher priorities such as MSR. The Senate proposal rejects that move and would provide $35 million more than requested as well as a further $30 million should MSR be canceled. “The ability to achieve the science goals of the decadal survey should not be contingent upon the performance of any project of the Planetary Science Division,” it states.

Shaheen Nelson appropriations 2023.jpg

Sen. Jeanne Shaheen (D-NH), the lead Senate appropriator for NASA, speaks with NASA Administrator Bill Nelson.

(Bill Ingalls / NASA)


Compared to the other divisions, proposals for the Astrophysics Division’s budget are less divergent. The administration proposed an increase from $1.51 billion to $1.56 billion, the Senate an increase to $1.54 billion, and the House a cut to $1.49 billion.

Major space telescopes. The Nancy Grace Roman Space Telescope’s annual budget is set to continue ramping down this fiscal year, from $447 million to $407 million, as it proceeds toward its target launch date in 2027. The James Webb Space Telescope’s operating budget is set to increase from $163 million to $187 million, a figure that is expected to remain steady going forward. NASA Astrophysics Division Director Mark Clampin said in October that the agency may reduce the operating budgets of the Hubble Space Telescope and the Chandra X-Ray Observatory in view of expected topline budget constraints. NASA requested steady funding levels for them of $93 million and $69 million, respectively.

Habitable Worlds Observatory. NASA is currently funding “precursor” science and technology activities before it formally establishes a Great Observatories Mission and Technology Maturation Program (GOMAP) in response to the latest National Academies decadal survey for astronomy and astrophysics. The survey recommended establishing such a program to ensure the smooth development of future flagship space telescopes, beginning with an ambitious mission concept called the Habitable Worlds Observatory that would boast leading-edge capabilities allowing it to conduct advanced exoplanet studies. Clampin said in October that he is committed to protecting the budget for efforts to move the concept forward.

Probe mission. The decadal survey also recommended that NASA pursue a medium-scale “Probe” mission that would close gaps in observational capabilities and launch well ahead of the Habitable Worlds Observatory. NASA closed its solicitation of proposals for Probe concepts in November and expects to select two or three for advanced studies. NASA requested $7.5 million for the Probe program in fiscal year 2024.

Biological and Physical Sciences

The administration proposed to increase the budget for the Biological and Physical Sciences Division from $85 million to $97 million, but the Senate proposes $90 million and the House proposes level funding. The division funds research conducted aboard platforms such as the International Space Station. A National Academies decadal survey released this year argued the division’s budget should be in the range of $1 billion, observing that its research is integral to plans for human deep-space exploration and expanding the commercial space sector.

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