About this Article

Laura Watkins (lwatkins[at)stsci.edu) and Julia Roman-Duval (duval[at]stsci.edu)

Published February 5, 2026

The Space Telescope Users Committee (STUC) met virtually on December 18 and 19, 2025. The meeting was originally planned for mid-November in person, but was postponed due to the U.S. government shutdown. Due to the short notice of the rescheduling and the proximity to the winter holidays, the rescheduled meeting was held virtually. This is not a permanent change, and the spring 2026 meeting will once again be held in person.

At this meeting, we welcomed back Harry Teplitz (Caltech/IPAC) as interim chair and welcomed Megan Reiter (Rice University) as vice chair. We also welcomed three new members: Joe Burchett (New Mexico State University), Griffin Hosseinzadeh (University of California, San Diego), and David Zurek (American Museum of Natural History).

Two members ended their terms of service, and we said goodbye to Harry Teplitz (chair of the 2024 meetings and fall 2025 meeting) and Ata Sarajedini (Florida Atlantic University, chair of the spring 2025 meeting). We are very grateful for their leadership, and for the expertise and contributions they brought to the STUC.

This article summarizes the December meeting. We encourage the community to view the complete set of presentation slides on the STScI website. The STUC is writing a full report with recommendations based on the information presented. The report will be made available on the STUC web page when it is finalized.

Meeting Summary

Hubble continues to excel.

In presentations from STScI and the HST Project at GSFC, the STUC heard updates about Hubble’s impressive science and mission operations, and the transformative science it continues to enable. Hubble continues to generate over 1,000 peer-reviewed publications each year and remains in very high demand (with a 6 to 7:1 oversubscription).

STScI teams continue to deliver science-ready products and tools to lower the barrier to analysis of Hubble science data. In particular, the new Hubble Spectroscopic Legacy Archive (HSLA) provides users with automated co-added Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS) spectra for individual targets classified by type, providing the widest possible wavelength coverage, highest possible signal-to-noise ratio, and latest calibration.

Hubble’s scheduling efficiency is around 50 to 55% in Reduced Gyro Mode (RGM), which is better than anticipated and only slightly reduced from the three-gyro mode scheduling efficiency (55 to 58%). The scheduling efficiency is capped at around 60% owing to Earth occultations. Following a period of more frequent stalls from fine guidance sensor (FGS) 2 in early 2025, the observing success rate has been back to its nominal baseline of over 90% for several months.

There is very high probability that Hubble will continue to generate unique, impactful science into the 2030s.

Lifetime extension efforts are continuing to mitigate system degradation, and ensure the longevity and productivity of the observatory well into the next decade. All instruments are performing nominally and are projected to have a > 90% reliability into the next decade. Three fine guidance sensors (FGS), two gyros, and four reaction wheels (RWs) remain operational. There is a > 90% probability that at least two FGSs, one gyro, and three RWs will be operational in 2030, which Hubble needs to operate nominally. The Science Instrument Command and Data Handling (SCI&DH) — whose B side failed in 2021 — is on track to have B side operations available in early 2026, thus restoring redundancy in the SCI&DH and increasing the reliability of the SCI&DH to 82% in 2030. Additionally, the atmospheric re-entry probability is < 10% before 2030, with the median re-entry prediction being mid-2033.

Hubble’s UV-visible capabilities are unique and will not be matched until the Habitable Worlds Observatory (HWO) is operational.

These capabilities keep Hubble at the forefront of scientific discovery, and are indispensable to address decadal priorities alongside other synergistic observatories, such as JWST and Roman. In the area of Time Domain and Multi-Messenger Astrophysics (TDAMM), Hubble’s responsiveness enables rapid follow up of transient events. In August 2025, a new Hubble response time record was set, taking observations of a kilonova candidate discovered by LIGO just 23.5 hours after the target of opportunity activation was triggered (the previous record was 34 hours). In July, Hubble took the sharpest-ever image of the interstellar comet 3I/ATLAS, which enabled the first measurement of its size.

Budget uncertainty and risk continue for Hubble.

Since March 2024, the Hubble budget has been threatened with significant reductions, first as part of the Operations Paradigm Change Review, and then the 2025 NASA Senior Review of Astrophysics missions. The president’s budget request from May 2025 for Hubble is $85 million in FY26 and $80 million in FY27, compared to a historical level of $98.3 million and $93.3 million in FY23 to FY25.

Note that while Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) and Wide Field Camera 3 (WFC3) IR are still fully supported, reductions in observer and calibration support for those modes are still under consideration pending appropriations for NASA in FY26 and beyond.

During the STUC meeting, the Hubble project at GSFC announced that the GO/AR grant funding level for Cycle 33 would be set at $10 million (compared to ~$15 million in Cycles 31 and 32, and ~$30 million in prior cycles) to mitigate the risk of budget reductions in FY26, FY27, and beyond. (Subsequently, NASA increased the Cycle 33 grant funding level to $12 million following FY26 appropriations in January 2026. Budget letters were distributed on January 30.) The ~$8 million/year NASA Hubble Fellowship Program (NHFP), which supports up to 72 Hubble, Sagan, and Einstein fellows each year, continues to be fully funded under the HST budget.

There’s lots more to come.

The STUC also heard updates on and had the opportunity to discuss the results from the Cycle 33 Telescope Allocation Committee (TAC) and plans for the Cycle 34 TAC. Notably, the Cycle 34 call for proposals includes a new HWO Precursor Science Initiative to encourage investigations with Hubble that will support HWO science planning, and inform mission architectures and trades with the goal of reducing HWO’s future design and development cost and risk.

The STUC was also updated on three upcoming policy changes to Director’s Discretionary (DD) programs, Community Target of Opportunity programs, and the Long-Term Monitoring DD working group; the modernization of the TAC process; and explorations of the timing of both the HST and JWST TACs. In addition, the STUC heard presentations with updates from the STScI Office of Public Outreach, the HST Project Communications and Outreach, and the Rocky Worlds DD program. There was also an in-depth look at how long-term planning and short-term scheduling is done for Hubble, including the remarkable efforts that are required to enable extremely rapid follow up of transient events.

Feedback

We encourage the community to provide feedback to STScI and to the STUC. Comments to the STUC chair may be made via the link on the STUC webpage.

Service on the Space Telescope Users Committee

Would you like to serve on the STUC? Nominations for STUC membership may be submitted at any time by email to stuc-nominations@stsci.edu. Self-nominations are welcome, but not required. Submissions are encouraged, but not required, to include a brief cover letter and curriculum vitae summarizing the nominee’s relevant background and HST-related interests. While members must be affiliated with institutions in the U.S. or in ESA countries, there is no restriction on citizenship. Nominations will be considered on a rolling basis, as several members rotate off after every meeting, approximately every six months.