Number 33, July 2005


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 

	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

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 

	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 

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:

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.

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