Content: 1) Progress Toward 1-wheel Operations 2) Cycle 6 Proposal Results in the Light of 1-wheel Operations 3) Plans For FUSE Cycle 7 4) Reminder: FUSE Based PhD Theses 1) Progress Toward 1-wheel Operations The FUSE team has made steady progress toward returning FUSE to scientific operations after the loss of the third (out of four) reaction wheels back on 27 Dec. 2004. After 1.5 months of effort to improve FUSE safe modes with a single operational wheel, it took just over 1 month to develop, test, and upload an initial "proof of concept" 1-wheel attitude control mode. This revised flight software was uplinked on 22 Mar. 2005, and was used for several weeks of successful test operations, including demonstrations of sub-arcsecond fine pointing control, observations of several previous targets (which demonstrated no changes in scientific performance [resolution or sensitivity from the hiatus), and observations of a small number of new Cycle 5 science targets. On 17 April 2005, another hardware failure occurred when the redundant roll axis gyro failed. This would not have caused a problem in the previous 2-wheel control mode because we had already developed the capability to operate with any number of gyros (including zero if necessary). However, the initial 1-wheel system we were operating at the time required three gyros again for fine pointing (science mode) to work, and so we had to go offline for science while this problem was addressed. Over the following 1.5 months, this change and several other improvements arising out of our earlier on-orbit experience were incorporated into the control system. During the first week of June 2005, we were back on the sky and demonstrated sub-arcsecond pointing with the so-called "gyroless" version of the 1-wheel control software! During the offline period in late-April and May, an equally important set of activities was taking place on the ground system side of the project. The science operations staff at JHU has been working furiously to develop new software tools that are providing insights into how and where on the sky we will be able to operate as a function of time. Scheduling science timelines with this initial generation of tools is a labor-intensive process. However, we expect to refine these planning tools considerably over the coming months. This "learn by doing" and "develop tools over time" approach closely parallels our 2001 recovery into 2-wheel operations, and is deemed the best compromise between getting back on the sky and getting some science (near term) while developing and improving capabilities (longer term). If you want to follow developments more closely, FUSE Mission Status Reports are posted 1-2 times per month on the FUSE web site: Or peruse the Status Report Archive for more details of this and previous times in the life of FUSE: 2) Cycle 6 Proposal Results in the Light of 1-wheel Operations The results of the FUSE Cycle 6 proposal review were announced by NASA in April 2005. The demand for FUSE observing time in Cycle 6 was greater than in any previous year. A total of 28.6 Msec of observing time was requested by 183 GI proposals. Standard proposals oversubscribed the expected amount of Cycle 6 observing time by 4.5X and Legacy proposals by about 3X. A summary of Cycle 6 proposal statistics is being posted on the GI web site http://fusegi.pha.jhu.edu. The proposal review was held in mid-November 2004. The reaction wheel failure in December 2004 imposed new observing constraints, necessitating further technical review of the Cycle 6 proposals. In addition, the delay in resuming science operations meant that there would be less observing time available in Cycle 6. As a result, the Cycle 6 proposals previously recommended for selection were subjected to the following additional technical feasibility criteria. (1) It was anticipated that observations in the Survey Exclusion zone (06h < RA < 18h and -30 deg < DEC < +30 deg) could not be observed. Such observations would have been difficult previously and are not feasible for Cycle 6. (2) No moving target (solar system) observations because there was no time to develop the necessary software for the new control mode. (3) The Cycle 6 Legacy and non-TOO Standard time allocation should not exceed about 4100 ksec, a 35% reduction from the previously planned time allocation. NASA approved 57 proposals for Cycle 6: 7 Legacy programs (1488 ksec in Cycle 6 and 1145 ksec in Cycle 7), 41 Standard programs (2813 ksec, including TOO time), and 9 Survey programs (1858 ksec). The smaller time allocation made the over-subscription about 6X, and many meritorious proposals could not be accepted. NASA is currently assessing the technical and scheduling requirements of all observing programs with pending observations. Sky coverage with the 1-wheel control mode will be more restricted than in the past. It is already evident that observations with timing requirements (ephemeris observations, roll angle, coordination with other facilities, etc.) will not be possible to schedule in the manner originally proposed. Observations in some parts of the sky may not be feasible, particularly in the region centered at RA = 12h and DEC= 0 deg. The FUSE project will be in contact with the PIs of current programs as this technical review progresses. 3) Plans For FUSE Cycle 7 NASA will accept FUSE Cycle 7 observing proposals through the ROSES NRA as previously announced. This observing cycle will solicit new targets only in the restricted parts of the sky where preliminary sky accessibility estimates indicate that significant exposure times will be available. Preliminary sky coverage assessments for the FUSE 1-wheel mode are indicating that the sky at absolute declinations above about 50-55 degrees will be accessible. There appears to be some sky coverage at lower declinations at certain times, but these constraints will not be understood in time to be included in Cycle 7. For the high declination range the observing efficiency is expected to be relatively high, as most of those targets will be observed in the Continuous Viewing Zone (CVZ). Hence it is important for the productivity of the FUSE mission to enhance the database of high priority targets in those parts of the sky. The Cycle 7 proposal deadline is September 16, 2005. The Cycle 7 GI program description and proposal instructions, including official statements about allowed target regions, will be posted on the FUSE GI web site at the beginning of August 2005. 4) Reminder: FUSE Based PhD Theses We'd like to remind you that the FUSE project maintains a web page listing all Ph.D. theses that have used or been supported by FUSE data and grants. When available, we also provide links either to an on-line summary of the thesis work or to the thesis itself. We also list theses that are still in development. Please see: If you or your students know of Ph.D. theses using FUSE data, please submit the relevant information to the FUSE Webmaster account at: fuseweb@pha.jhu.edu Please include Full Title, Full name of the Ph.D. recipient, granting institution, month and year of degree (or when expected), and any links to on-line information. See the web page for examples.
The Observer's Electronic Newsletter is published by the FUSE project and is aimed at the FUSE user community.
Editor: B-G Andersson, FUSE Guest Investigator Officer.
The FUSE Project is managed by the Johns Hopkins University's Center for Astrophysical Sciences in Baltimore, MD, for NASA's Goddard Space Flight Center. The FUSE Principal Investigator is Dr. Warren Moos, the FUSE Program Manager at JHU is Mr. Randy Ewing, and the NASA Project Scientist for FUSE is Dr. George Sonneborn.