Subject: Support of HTV-X mission From: Carabajal, Claudia C. (GSFC-61A.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] Dear ILRS colleagues, See the message below from Shinichi Nakamura, with JAXA. The ILRS approved the support of the HTV-X mission. The mission would like to start ILRS support in March. The particulars of the mission are included in the message. Updates to the ILRS webpages will follow. We will be moving the mission from Future Missions to Current missions. https://ilrs.gsfc.nasa.gov/missions/satellite_missions/future_missions/index.html https://humans-in-space.jaxa.jp/en/htv-x/ JAXA plans to distribute the CPF via CDDIS and EDC. When distributing the CPF, the mission will announce via the ILRS-station mailing list the specific times when SLR observation is possible. We are advising the mission to also email the community through SLR Mail, as we are doing here. Once the date HTV-X detaches from the ISS and the date SLR observations become possible are confirmed, JAXA will promptly report this to the ILRS. Regards, Claudia. —————————————————— Dear Claudia Dear ILRS CB Dear ILRS GB Dear ILRS MWG, JAXA would like to report recent progress of HTV-X observation. SLR observations of HTV-X, listed in ILRS`s Future Mission, will commence in March. This is approximately six months later than originally planned. In the HTV-X experiment, the HTV-X will perform a pendulum motion, and by observing this from the SLR station, the attitude variation of the orbital object will be estimated. This pendulum motion consumes a large amount of fuel. Therefore, the HTV-X will only point its reflector toward Earth during the pendulum motion. JAXA plans to distribute the CPF via CDDIS and EDC. When distributing the CPF, we will announce via the ILRS-station mailing list the specific times when SLR observation is possible. Specifically, once the date HTV-X detaches from the ISS and the date SLR observations become possible are confirmed, we will promptly report this to you. For your reference, we are sharing HTV-X`s parameters. https://ilrs.gsfc.nasa.gov/missions/satellite_missions/future_missions/index.html [gcc02.safelinks.protection.outlook.com] HTV-X Parameters Sponsor: JAXA Expected Life: Up to 18 months after leaving the ISS Primary Application: ILRS Mission Request COSPAR ID: 2025-241A ILRS ID 2524101 SIC Code: 1559 Satellite Catalog (NORAD) Number: 66174 Launch Date: October 21, 2025 LRA Diameter: Approx 12 cm LRA Shape: A pyramid with the apex of a hexagonal pyramid cut off Reflectors: 7 CCRs in LRA Orbit: ISS orbit Inclination: 51.7 deg Eccentricity: Approx 0 Perigee: Approx 400 km∼430 km Period: Approx 91 minutes Weight: 16,000 kg (Launch Mass) Best Regards Shinichi Nakamura [cid:image001.png@01DB8E97.5E4A11C0] Claudia C. Carabajal Research Scientist SME HBG Geodesy & Geophysics Group Lead Secretary, ILRS Central Bureau Geodesy and Geophysics Laboratory, 61A NASA Goddard Space Flight Center 8800 Greenbelt Rd., Greenbelt, MD 20770 Claudia.C.Carabajal@nasa.gov