A billion dollars short: A progress report on the Planetary Decadal Survey

Takeaways:

• In the first two years of this decadal period (2023 - 2032), NASA spent $1.04 billion less on planetary science than outlined in the decadal survey's Level Program, and $1.27 billion less than outlined in the Recommended Program.
• NASA is on track to spend $5 billion below the Level Program and $11 billion below the Recommended Program over the 10-year decadal period.
• These funding discrepancies will delay high-priority planetary science missions and reduce the cadence of missions in the coming years.
• Budgetary corrections can still change course and significantly improve the mission outlook of this decadal period.

The planetary science decadal survey is the foundational planning document for NASA’s Solar System exploration efforts. Organized by the National Academy of Sciences, Engineering, and Medicine and crafted by the scientific community, this 10-year planning document outlines the most important questions in planetary science and recommends the missions and programmatic investments necessary to answer them.

The decadal period began in 2023, so only two years of finalized NASA budgets can be fully analyzed, though NASA has provided detailed program projections through 2029. Using this initial data, we found that NASA's spending on planetary science is already more than $1 billion below the amount projected by the decadal survey, with significant shortfalls expected to continue for the next five years.

If these trends continue, there will be a $5 to 11 billion shortfall in planetary science funding by 2032. These missing billions will reduce the rate of medium and small planetary missions, severely delay new flagship missions to Uranus and Enceladus, and severely constrain options for implementing Mars Sample Return.

There is good news. Some decadal priorities, such as increasing fundamental research funding and pursuing planetary defense, are progressing in line with recommendations. There is also plenty of time yet for programmatic and budgetary course corrections to compensate for this initial drop in resources.

However, absent near-term action, NASA will launch fewer planetary missions, do less science, and make fewer breakthroughs in knowledge than otherwise possible in the coming decadal period.

Two paths forward: the Level and Recommended programs

Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032, referred to here as the “planetary decadal,” was released in April 2022 and provides policy and program recommendations for NASA's Planetary Science Division (PSD) for the years 2023 to 2032. An overview of the planetary decadal’s recommendations is available here. In brief, the planetary decadal identifies 12 priority science questions and a comprehensive set of mission and programmatic recommendations to help answer them.

The planetary decadal outlines two paths forward to accommodate two different budgetary scenarios: the Level Program and the Recommended Program. The Level Program represents the minimum acceptable level of investment that would still address the major scientific questions, assuming reasonable budget growth. The Recommended Program is the preferred option and requires more funding.

The decadal estimated that the cost of pursuing the Level Program would be $35 billion over 10 years, with $41.1 billion necessary for the Recommended Program. For context, NASA expenditures on planetary science in the previous decadal cycle (2013 - 2022) were roughly $21 billion. Adjusting for inflation, this is equivalent to $25.3 billion in 2024 dollars. Either program represents a substantial increase in funding over historical trends.

Using spending as a measure of decadal commitment

Budgets are not the only way to judge progress on the planetary decadal, but they do provide a useful and quantitative metric to measure commitment by the United States government. A dollar can only be spent once, and where those dollars go is a good proxy for the political priority of a program. 

Methodology

For our analysis, we will look at the proposed funding levels beginning in fiscal year 2023 (Oct. 1, 2022) and ending at the end of fiscal year 2032 (Sept. 30, 2032). This represents the current decade covered by the planetary decadal.

Two budgetary charts in the planetary decadal (Figs 22-1 and 22-2) show the Recommended and Level Program cost estimates, broken out by major program, for each year in the current decadal period. From the chart, we can estimate the numerical amounts and compare them with NASA's current and planned spending on its Planetary Science Division (PSD). We do so in the following way:

• For FY 2023, we have NASA’s operating plan, which shows how much money was obligated to the program from Oct. 1, 2022 to Sept. 30, 2023.
• For FY 2024, we will use NASA’s spending plan from June of 2024, which is based on the enacted budget passed by Congress. This covers Oct. 1, 2023, to Sept. 30, 2024. 
• For FY 2025, we will use the President’s Budget Request (PBR) for NASA, which covers Oct. 1, 2024, to Sept. 30, 2025. Congressional action on this request is not complete at the time of publication.
• For FYs 2026 to 2029, the PBR includes notional budgets for the four out-years beyond the immediate fiscal year. These are not formal requests but an intention by the Administration for its future budget proposals. The PBR estimates a 2% year-over-year increase in the PSD topline. This covers Oct. 1, 2025, to Sept. 30, 2029.
• For FYs 2030 to 2032, we continue the 2% growth trend to the PSD topline. This will round out the decadal period, covering Oct. 1, 2029, to Sept. 30, 2032. This is a projection based on available data and does not represent a formal budget proposal from the White House, Congress, or the scientific community.

Combining both the Decadal and NASA budgetary data, we generate the following data:

Analysis: NASA is falling short on both the Level and Recommended planetary programs

NASA is on track to fall $5 billion short of the Level Program outlined in the decadal survey. Compared to the Recommended Program, NASA stands to miss the mark by $11 billion — approximately half of what the agency spent on the entire planetary program in the previous decade. These shortfalls are likely to stall progress on the scientific objectives outlined in the decadal survey.

This is apparent when comparing the budgetary charts of NASA's projected planetary program spending to the Level Program proposed by the decadal:

The differences are more stark when comparing NASA's projected spending on planetary science to the decadal's Recommended Program:

To understand the implications of this significant budget shortfall, we have to dig deeper into funding for each program category over the decade. The decadal survey divides its proposed budgets into program elements that line up almost exactly with the federal budget. The major difference is that a handful of mission-specific research programs, management overhead, NASA contributions to international missions are lumped into a program line named "Planetary Other". 

Although we can extrapolate 2% growth to the PSD topline for FYs 2030 to 2032 (the years beyond the current five-year budget projection), that growth will not be distributed equally due to the variety of program development schedules and development timelines. Rather than making broad estimates, we limit our programmatic comparisons to NASA's projected planetary spending through FY 2029.

Budgetary highlights of decadal priorities

There are many programmatic and mission recommendations in the decadal survey. We address a handful below to highlight the general trend for new mission starts and scientific research support.

Flagship missions

The top decadal flagship mission priority, Mars Sample Return (MSR), is a major source of discrepancy between NASA's projected funding and the decadal projections. According to FY 2025 projections, funding for MSR will decrease to $100 million per year in 2026 — far less than needed for the program. This decline represents the programmatic limbo in which MSR finds itself. NASA is looking for radical new ways to structure the program in order to control its costs (which the decadal assumed to be $5.3 billion over its lifetime, but had grown to nearly double that). Once a new plan for MSR is confirmed, its budget will need to grow in a way that does not put additional pressure on other important missions. The decadal recommendation was that MSR never exceeds more than 1/3 of the total planetary budget and that NASA should seek congressional budget augmentation if necessary. To the agency's credit, MSR has not been canceled, and it remains the stated priority of the Planetary Science Division, even during this period of uncertainty.

The decadal's Level and Recommended programs include the start of a Uranus Orbiter flagship mission. NASA is currently projecting a funding ramp-up to begin "formulation studies" of a Uranus orbiter beginning in FY 2027. The Level Program recommendation was to start the mission in FY 2028. NASA is thus projecting a plan consistent with the Level program, though we note that the funding ramp-up may not be rapid enough to launch before 2032.

Small- and Medium-class missions

The Level Program in the planetary decadal recommends one to two medium-class New Frontiers and five small-class Discovery missions be selected between 2023 and 2032. So far, no selections have been made. The current missions in development (VERITAS and DAVINCI for Discovery, Dragonfly for New Frontiers) are remnants of the prior decadal period and have all experienced delays and budget growth. The next call for new mission proposals is not expected until late 2026, with selections likely to be made the following year. Funding for future Discovery and New Frontiers missions doesn’t begin to increase in the FY 2025 President’s Budget Request until FY 2028, and is consistent with one new New Frontiers mission and one new Discovery mission. This makes NASA's plans consistent with the Level Program for New Frontiers. NASA would have to follow the 2027 Discovery selection with a new Discovery mission selection per year for each subsequent year to meet the decadal recommendations, however. It's not impossible (NASA has occasionally selected two Discovery missions at a time), but it will be difficult if the agency is also ramping up a Uranus Orbiter mission and working on MSR at the same time.

Planetary Defense

Planetary Defense is a relatively bright spot, funding-wise, in the current budget projections. Spending on this activity is expected to exceed both the Level and Recommended Programs outlined in the planetary decadal. This does not, however, mean that NASA is adding new missions and activities. NEO Surveyor, the priority mission outlined in the decadal, will cost more than expected to build and launch, which accounts for the additional funding. There is no funding for a follow-on planetary defense mission after NEO Surveyor, which was the recommendation of the Level and Recommended decadal programs.

Research and International Flight Opportunities

The planetary decadal recommends allocating 10% of the PSD budget to the Research and Analysis (R&A) program. If enacted, the amount provided for R&A in the President’s FY 2025 Budget Request would meet this benchmark. Future projections have R&A funding above 10% of the PSD topline through the end of the decade.

Funding for the "Planetary Other" activities, which includes management, mission-specific R&A, and contributions to international planetary exploration missions, meets or exceeds the Level and Recommended funding amounts, another positive sign for research funding. However, international contributions account for approximately 35% of the Planetary Other program for the FY 2023-2029 time period. EnVision and the Rosalind Franklin Rover, both ESA missions with major NASA contributions, account for a substantial amount of this funding.

Why is this happening?

NASA has lost significant buying power in the past few years, a combination of inflation and congressionally directed cuts starting in fiscal year 2024. It resulted in the largest funding gap between the President’s Budget Request and the final congressional appropriation in three decades. The majority of NASA’s cuts—$457 million—were levied against the Science Mission Directorate and Mars Sample Return. Other aspects of the planetary budget are held flat, still functionally a cut due to the effects of inflation. Without budget growth, NASA programs are unable to keep pace with inflation, supply chain, and other economic pressures. And since scientific exploration isn’t a mass commodity, NASA ends up doing less science with less money. 

This is manifesting already in the cancellation of the VIPER mission to the Moon, the delay of MSR and future Discovery and New Frontiers missions, and the proposed end of the Chandra X-Ray Observatory, which just celebrated 25 years of operation. And although both the House and Senate have proposed budgets that provide sufficient funding for some programs like Chandra and the Lunar Discovery & Exploration Program, the problem is endemic to how budgets are being crafted in Washington. Neither the Senate nor the House's budget proposals reverse this overall trend; in some cases, congressional directives would actually make the overall budget pressure worse by increasing funding for a handful of favored programs without increasing NASA's topline science budget, forcing cuts elsewhere.

The source of this budget crisis is the Fiscal Responsibility Act (FRA). The FRA resulted from a deal made in May 2023 between then-Speaker of the House Kevin McCarthy (R-California) and President Joe Biden (D) to prevent a default on the nation’s debt. In exchange for protecting the full faith and credit of the U.S. government, the deal included limitations on how much money could be spent on discretionary budgets, which includes NASA, for fiscal years 2024 and 2025. The size of the budgetary pie shrank, and federal programs across the board were cut as a consequence. For NASA, this means delays, cancellations, and significant workforce reductions.

If this sounds familiar, it should. In 2011, Congress passed the Budget Control Act to extend the debt limit, which included reductions to federal spending that were applied across the entire discretionary budget. These budget cuts, known as sequestration, led to a major budget shortfall for NASA, which reduced support for numerous space exploration projects and activities at a similar time in the previous planetary decadal, delaying and canceling missions, such as ExoMars, Perserverance, and reducing the rate of competed missions.

Clean-up crew

Because space missions take many years to develop, launch, and operate, there is a non-linear relationship between the amount spent in one year and the outcome of that mission. Simply put, the less the government spends in the immediate term will have a multiplying effect on delays to development and increase overall lifetime costs.

But as with sequestration, there is hope for NASA science funding after the expiration of the FRA budget caps (or possibly before). In the years after sequestration took root, the federal budget for planetary exploration experienced a fiscal renaissance, growing at an average annual rate of 11.3% per year. The PSD budget began the last decadal period at just over $1.2 billion and, over 10 years, more than doubled to $3.1 billion in FY 2022. This restoration of funds enabled faster selections of competed missions and the implementation of two flagship missions: Perseverance and Europa Clipper.

The negative effects of the FRA’s indiscriminate cuts are being felt across the government. Senator Patty Murray (D-Washington), the Chair of the Senate Appropriations Committee, has railed against the cuts on the floor of the U.S. Senate. In her speech, the Senator stated, “I can’t emphasize enough that, under the caps for nondefense, everything struggles to keep up with rising costs.” And in a show of bipartisan dread for these cuts, Senator Jerry Moran (R-Kansas), who is the second-in-command of the Commerce, Justice, Science Subcommittee with direct oversight of the NASA budget, said, “Space is the place we have to focus our attention, and that means more resources and developing a workforce that can meet the needs of the country…. [The] challenge is that we are limited by the dollars that were provided.” Sen. Murray also expressed, “And I can’t, for the life of me, understand why we would want to go through something like that again [in FY 2025].” There is an appetite at the highest levels of government to reverse the indiscriminate cuts against the budget that, in the case of NASA, have caused serious harm and put the agency behind schedule on achieving the first-rate science that it’s known for, defined by documents like the decadal survey.

Conclusion

NASA is falling behind decadal recommendations for funding planetary science. But this can be corrected; the sooner, the better.

After the arbitrary budget caps are lifted, in FY 2026 or possibly earlier, there remains a path to get NASA PSD back on track to the Level Program funding levels. This would require Congress to renew its commitment to planetary science, much like the reinvestment that followed sequestration in 2013. The upcoming presidential and congressional elections will set the tone and the politics of these critical few years for planetary science. A divided government tends to lead to more spending cuts, while a unified government can be more open to budgetary growth for agencies like NASA. It will be up to the scientific community and its supporters to make the case for renewed investment in space science at NASA, regardless of the outcome.

Ultimately, we must keep perspective. If NASA falls short of decadal projections for spending on planetary science, it doesn’t mean exploration won’t happen over the next ten years. It just means that it’ll happen at a slower pace, with fewer new opportunities for the scientific community to propose missions to respond to emerging questions in the scientific exploration of the Cosmos. But there is always room for correction, for new ideas and new discoveries, for renewal and recommitment. It's a big Solar System out there, and there are myriad worlds patiently waiting to be explored.