In its June 2025 the Canadian Astronomical Society (CASCA) stated that discussions were underway between the National Research Council Canada (NRC) and the Canadian Space Agency (CSA) for a Phase A+ study for the CASTOR space telescope. Will 2026 finally be the year this long sought after community project get underway?
While space defence, commercial space and Moon related projects dominated the headlines with several funding announcements in 2025, space science projects lag far behind.
The Cosmological Advanced Survey Telescope for Optical and UV Research (CASTOR) space telescope was first identified in 2010-2020 Long Range Plan for the astronomy community. Since then a lot of work has been done, but pushing the project forward has been slow going due to lack of government support. The last, and only, Canadian led space telescope effort was the highly successful MOST (Microvariability and Oscillations of Stars/Microvariabilité et Oscillations STellaire) space telescope launched in 2003 and retired in 2019.
In it’s latest on December 21, 2025 CASCA outlined the following updates to CASTOR the mission:
- Lobbying Efforts – Since October, the Coalition for Canadian Astronomy has met on multiple occasions with government representatives. On all accounts, the government appears supportive of the mission, although no line item was explicitly earmarked for CASTOR in the November 4 budget. Meetings between the government and Coalition continue.
- 2025 Mid-Term Review
- The 2025 Mid-Term Review, which was released on November 21, contains several recommendations directly related to CASTOR. The first, and most important, is the continued strong endorsement of the project as a top priority for the community in space astronomy (recommendation S01 [LRP#26]).
- It is also notable that S04 [LRP#27 and #34] urges Canadian agencies to consider ways in which CASTOR development can be leveraged as a pathfinder for UV instrumentation on a future international flagship mission (see below)
- Phase A+ Study Planning
- CSA and NRC have held several high-level meetings throughout the fall with the aim of better defining roles and responsibilities during a proposed Phase A+ study (which remains the Coalition’s top priority in space astronomy).
- Since September, NRC has directed internal resources to the development of a comprehensive Project Management Plan for the expected Phase A+ study. It is hoped that a preliminary version of the plan will be available in early January 2026; CSA and NRC are working together to refine and optimize the plan, including the development of a plan for governance framework.
- Habitable Worlds Observatory (HWO) Request for Information – In November, several members of the CASTOR team submitted a response to the CSA Request for Information on Canadian Contributions to the Habitable Worlds Observatory (HWO). That report focused on how CASTOR might be leveraged to provide a pathway for a possible Canadian contribution to HWO (see recommendation S04 [LRP #27/34] from the MTR). Any decision on possible Canadian participation in HWO, however, must be defined by the community in LRP2030.
- Detector Testing
- The long-term detector testing and characterization program is continuing. This is a collaboration between NRC, JPL, Teledyne-e2v, Open University, CSA, the University of Calgary and the University of Manitoba. Tests are being carried out by NRC-HAA in Victoria and the University of Calgary. The Vacuum UV Laboratory (VUVL) at Calgary has been extensively upgraded in anticipation of these tests, with the final “bake out” of the VUVL now underway.
- Tests performed on the CIS120 engineering device in Victoria have provided data on the read noise and dark current performance of the device, with some puzzling results that are being analyzed by the consortium. Tests on the delta-doped CIS120s will likely commence in Calgary in January 2026.
- UVMOS Proto-Typing – The three-year, $2M NRC Small Teams project to build a prototype of a DMD-based UVMOS instrument continues to make steady progress. The next team meeting will take place in Marseille, in July 2026. This project aims to reach a TRL of 6 by mid 2027. The technologies under development are relevant to both CASTOR and, potentially, HWO (see above).