NASA considering budget cuts for Hubble and Chandra space telescopes

NASA is currently contemplating reducing the budgets of its prominent space telescopes, the Chandra X-Ray Observatory and the Hubble Space Telescope, due to broader spending reductions in its astrophysics programs. Mark Clampin, the director of NASA's astrophysics division, revealed during a presentation to the National Academies' Committee on Astronomy and Astrophysics on October 13th that he is exploring potential cuts in the operating budgets of these telescopes in order to allocate funds to other priorities within the division.

The motivation behind these potential cuts stems from the anticipation that the astrophysics division will not receive the full requested amount of approximately $1.56 billion for fiscal year 2024. This is due to legislation passed in June that imposes a cap on non-defense discretionary spending for 2024 at 2023 levels, with only a 1% increase for 2025.

Clampin stated, "We are operating under the assumption that the budgets for FY24 will remain at the levels of FY23. Consequently, we have made the decision to reduce the budget for missions in extended operations, namely Chandra and Hubble."

Clampin refrained from disclosing the specific amount by which the budgets of these observatories would be reduced, as well as the precise impact of the cuts on their operations. He emphasized that the proposed cuts are still under examination, highlighting that he was able to make a "positive adjustment" for Chandra just last week.

After the James Webb Space Telescope, Chandra and Hubble are the most costly astrophysics missions for NASA to operate. In its fiscal year 2024 budget proposal, NASA requested $93.3 million for Hubble and $68.7 million for Chandra, consistent with previous years' budgets. Together, these telescopes account for slightly over 10% of NASA astrophysics' budget request for fiscal year 2024.

They are also among the two oldest missions of NASA, with Hubble being launched in 1990 and Chandra in 1999. Clampin suggested that this was a reason for the reduction of their budgets. "Chandra is currently facing a number of issues. It is becoming increasingly difficult to operate," he stated. The insulation on the spacecraft's exterior is deteriorating, causing the spacecraft to warm up and making operations more challenging.

"While Hubble does not have these issues," he added, "it has been in operation for a significant period of time and it constitutes a substantial portion of the astrophysics budget."

Clampin mentioned that he was planning two "mini senior reviews" for Chandra and Hubble, most likely in May 2024 following the release of the fiscal year 2025 budget proposal. NASA conducts senior reviews to determine whether and how to extend the missions of scientific spacecraft that have completed their primary objectives.

During the most recent astrophysics senior review in 2022, Chandra and Hubble were effectively exempted, with separate panels examining each mission to identify efficiencies and other improvements, rather than evaluating whether the missions themselves should be extended.

"The final report of the 2022 senior review stated, 'Hubble and Chandra occupy the top tier due to their significant and wide-ranging impact on astronomy. Both missions are operating at an extremely high level of efficiency, and although they are showing signs of aging, they are likely to continue generating world-class scientific discoveries over the next five years, working in conjunction with the JWST as it assumes its flagship role.'"

Clampin mentioned that any savings from Chandra and Hubble would be allocated to other astrophysics priorities. "However, our aim is to safeguard future missions, the development of new missions, and international partnerships," he explained. This includes the Nancy Grace Roman Space Telescope, smaller Explorer-class astrophysics missions, and NASA's involvement in missions led by other nations, such as the ESA's LISA gravitational-wave observatory and the Israeli Ultrasat ultraviolet observatory.

They are also among the two oldest missions of NASA, with Hubble being launched in 1990 and Chandra in 1999. Clampin suggested that this was a reason for the reduction in their budgets. "Chandra is currently facing a number of issues. It is becoming increasingly difficult to operate," he stated. The insulation on the spacecraft's exterior is deteriorating, causing the spacecraft to warm up and making operations increasingly challenging.

"While Hubble does not have these issues," he added, "it has been in operation for a significant period of time and it constitutes a substantial portion of the astrophysics budget."

He expressed his desire to prioritize the early development of the Habitable Worlds Observatory, which is the next flagship astrophysics mission after Roman, scheduled to launch in the 2040s. "It is absolutely crucial to continue advancing the Habitable Worlds Observatory," he emphasized. This includes issuing the first call for proposals to develop key technologies for the large space telescope and providing funding for teams conducting research on science and technology topics related to it.

He further mentioned that NASA is also considering making "small reductions" to other ongoing missions, which he did not specify, as well as reducing spending on technology development.

All of these plans, he explained, are aimed at safeguarding against potential significant cuts in astrophysics funding. The Senate version of the commerce, justice, and science (CJS) spending bill for fiscal year 2024 would allocate $1.544 billion to NASA astrophysics, falling short of the requested amount but still higher than the $1.51 billion received in 2023. Details of the CJS spending bill from the House appropriators have not yet been publicly released.

"It is entirely possible that when we receive the appropriation, considering the current news landscape, we could end up with a funding level even lower than that of 2023," he cautioned the committee. "The outlook is not optimistic."