NOTE: Mission Status Reports on the web page will continue roughly once a week, as events unfold.

-- Bill Blair

---

The Satellite Control Center at JHU.

(Click image to see larger version.)

Significant Progress in FUSE Checkout!

The last 11 days has seen several important milestones in the FUSE checkout. Firstly, all four telescope baffle doors are now open! Barring any emergencies, they should stay that way for the remainder of the mission! Quite a crowd gathered in the Satellite Control Center to watch the telemetry flags switch over that showed the doors had opened successfully. All four telescopes can now "see" the sky.

Another important milestone was the dropping of telescope temperatures to what is called the "cold operate" level. This ended the "bake-out" period (used to drive trapped gases out of the structure) and set the stage for our first attempt to turn on the high voltage on one of the FUV detectors in the spectrograph, which occurred on Wednesday 8/11/99. This first attempt was partially successful, but full high voltage levels on detector 1 were not achieved (due to a software glitch). After analysis, the ramping up of high voltage was attempted again on (gulp!) Friday, August 13th, and it worked! We have spent this last weekend taking "background" data with detector 1 and making sure the software autonomously ramps the voltage up and down properly as we enter and exit the high particle background part of our orbit. This all appears to be working nominally.

As a conservative step, we will continue to operate this week with only one of our two detectors. We will exercise preliminary tests of the focus and alignment procedures that will be used later with both detectors (and all four mirrors), and we will perform additional target acquisition tests. Ramp up of high voltage on detector 2 is currently scheduled for early next week.

As an aside, the second stage of the Delta II rocket that propelled FUSE into orbit met it's demise on Aug. 4th, 1999. CLICK HERE for a report on this event, by FUSE astronomer Ed Murphy.

Reported by: Bill Blair, Chief of Mission Planning