FUSE is dead, long live FUSE!

The Far Ultraviolet Spectroscopic Explorer, a UV space telescope launched by NASA in June 1999 with a nominal lifetime of 3 years, ceased working for the last time on July 12th 2007.

FUSE Mission Status--Aug. 17, 2007
Dear Colleagues,

As reported previously in the FUSE newsletter, the last operational reaction wheel on FUSE stopped temporarily in early May 2007. It was restarted and science operations resumed on June 12. However, on July 12 the wheel stopped again. This time the stoppage was very abrupt indicating a large braking force. Attempts to restart any of the wheels over the last four weeks have been unsuccessful. Although the instrument remains in excellent condition, the FUSE satellite is currently incapable of the fine pointing control required to continue its science mission, and there is no real prospect for recovering this capability.

Regrettably, we have concluded that the scientific mission of the Far Ultraviolet Spectroscopic Explorer is no longer viable. The NASA Science Mission Directorate has accepted our recommendation to terminate the mission. The FUSE Project has started closeout activities and will complete the final CalFUSE 3.2 reprocessing of the entire science mission data set in mid 2008. The FUSE archive at MAST will be an ongoing legacy of the mission, and an important resource for years to come. Future editions of the FUSE Newsletter will provide details of our plans for the FUSE mission archive at
MAST. Also, watch the FUSE web page for updates.

The FUSE mission has been a fantastic success by any measure. 678 science programs (GI, PI team, and discretionary time) have obtained 67 Msec of observing time, over 5100 observations of about 2800 unique targets. There are over 430 peer-reviewed papers based on FUSE data and the number continues to grow. The story is not quite over, though. Twenty five of the 68 programs selected for Cycle 8 obtained data this Spring and Summer before the reaction wheel stopped for the last time. These data have been archived recently and should lead to further exciting results in the near future. Utilization of the FUSE archive will continue the flow of new results.

The Astrophysics Division intends to place special emphasis on FUSE archival research in the 2008 Astrophysics Data Program that will be part of the 2008 ROSES proposal solicitation.

The success of FUSE is a result of the combined efforts of the scientists and engineers who built and operated it plus the scientists who proposed, analyzed, and interpreted the observations. FUSE's legacy is a testament to the creativity, ingenuity, and hard work of all of you. We acknowledge your efforts and enthusiasm with gratitude.


George Sonneborn Warren Moos
Project Scientist Principal Investigator
NASA/GSFC Johns Hopkins University

Over the years scientists and engineers had worked wonders to overcome many hardware failures and software glitches to keep FUSE working beyond its normal lifetime, but this final problem with the reaction wheel appears fatal. FUSE will live on as scientists continue to analyze and re-analyze the data archive accumulated over its many years of successful observing.

Unlike the Hubble Space Telescope, which is primarily an imager, FUSE consisted of a set of four co-aligned UV-sensitive spectrometers (see the FUSE User Guide more a technical description of the instrument) and thus can not create pretty images of the sort that have made Hubble famous. FUSE has been very successful scientifically, but without images it is hard to convey this, and why it had unique capabilities that Hubble (or its eventual replacement JWST) can not match, to the public.