WASHINGTON — NASA is considering cutting the budget of two of its biggest space telescopes because it faces broader spending reductions for its astrophysics programs.
In an Oct. 13 presentation to the National Academies’ Committee on Astronomy and Astrophysics, Mark Clampin, director of NASA’s astrophysics division, said he was studying unspecified cuts within the operating budgets of the Chandra X-Ray Observatory and Hubble Space Telescope to preserve funding for other priorities within the division.
The potential cuts, he said, are driven by the expectation that his division won’t receive the complete request of nearly $1.56 billion for fiscal 12 months (FY) 2024 due to laws passed in June that caps non-defense discretionary spending for 2024 at 2023 levels, with only a 1% increase for 2025.
“We’re working with the expectation that FY24 budgets stay on the ’23 levels,” he said. “That implies that we now have decided to cut back the budget for missions in prolonged operations, and that’s Chandra and Hubble.”
Clampin declined to say how much the budgets of those two observatories could be cut, or specific impacts on them due to the cuts. He indicated the proposed cuts are still being studied, noting that he was in a position to make a “positive adjustment” for Chandra just within the last week.
Chandra and Hubble are the 2 most costly NASA astrophysics missions to operate after the James Webb Space Telescope. NASA requested $93.3 million for Hubble and $68.7 million for Chandra in its fiscal 12 months 2024 budget proposal, in step with past years’ budgets. Combined, they represent slightly greater than 10% of the fiscal 12 months 2024 budget request for NASA astrophysics.
Also they are among the many two oldest NASA missions, with Hubble launched in 1990 and Chandra in 1999. Clampin suggested that was a reason for reducing their budgets. “Chandra has quite a few issues without delay. It’s becoming increasing difficult to operate,” he said. Insulation on the spacecraft’s exterior is degrading, warming the spacecraft and making operations increasing difficult.
“While Hubble doesn’t have those issues,” he added, “it has been operating for a very long time and it’s a large piece of the astrophysics budget.”
Clampin said he was planning two “mini senior reviews” for Chandra and Hubble, likely in May 2024 after the discharge of the fiscal 12 months 2025 budget proposal. NASA conducts senior reviews to come to a decision whether and how you can extend science spacecraft which have accomplished their primary missions.
Within the last astrophysics senior review in 2022, Chandra and Hubble were effectively exempted, with separate panels studying each mission to search for efficiencies and other improvements slightly that examining if the mission itself needs to be prolonged.
“Hubble and Chandra occupy the highest tier given their immense, broad impact on astronomy,” the ultimate report of the 2022 senior review stated. “Each missions are operating at extremely high efficiency, and although they’re increasingly showing signs of age, each are more likely to proceed to generate world-class science throughout the following half decade, operating in concert with JWST because it begins its flagship role.”
Clampin said any savings from Chandra and Hubble would go to other astrophysics priorities. “What we are attempting to do, though, is protect future missions and developing missions and international partnerships,” he said. That features the Nancy Grace Roman Space Telescope, smaller Explorer-class astrophysics missions, and NASA’s role on missions led by other nations, resembling ESA’s LISA gravitational-wave observatory and the Israeli Ultrasat ultraviolet observatory.
He said he also desired to protect early work on the Habitable Worlds Observatory, the following flagship astrophysics mission after Roman slated to launch within the 2040s. “It’s absolutely fundamental to maintain moving Habitable Worlds Observatory forward,” he said. That features the primary call for proposals to develop key technologies for that giant space telescope and funding teams studying science and technology topics for it.
He added that NASA can be considering “small reductions” to other operating missions, which he didn’t discover, in addition to reductions in technology development spending.
All those plans, he said, were to guard against potential sharp cuts in astrophysics. A Senate version of a commerce, justice and science (CJS) spending bill for fiscal 12 months 2024 would give NASA astrophysics $1.544 billion, in need of the request but still above the $1.51 billion it received in 2023. House appropriators have yet to publicly release details about its CJS spending bill.
“It’s entirely possible once we get an appropriation, given what you see on the news day by day, we may very well be even well below the ’23 level,” he warned the committee. “It’s not a joyful outlook on the market.”