Kennedy Space Center, Fla.

May 18, 1998
STATUS REPORT : S-19980518
6:33 PM EDT

KSC Public Affairs Contact: Joel Wells (fax: 407-867-2692)

MISSION: STS-91 -- 9TH AND FINAL MIR DOCKING, SPACEHAB-SM, Alpha Magnetic Spectrometer (AMS)

VEHICLE: Discovery/OV-103
LOCATION: Launch Pad 39A
TARGET KSC LAUNCH DATE/TIME: June 2 at about 6:10 p.m. EDT
LAUNCH WINDOW: 7-10 minutes
MIR DOCKING DATE/TIME: June 4 at about 12:59 p.m. EDT
MIR UNDOCKING DATE/TIME: June 8 at about 12:01 p.m. EDT
TARGET KSC LANDING DATE/TIME: June 12 at about 2:03 p.m. EDT
MISSION DURATION: about 9 days, 19 hours, 53 minutes
CREW: Precourt, Gorie, Lawrence, Chang-Diaz, Kavandi, Ryumin, Thomas (down)
ORBITAL ALTITUDE and INCLINATION: 173 nautical miles/51.6 degrees
NOTE: Today, Shuttle engineers successfully completed the tanking test of the new super lightweight external tank (SLWT) set to fly for the first time with Shuttle Discovery on mission STS-91. From Firing Room No. 1, the test team subjected the external tank and orbiter to a simulated launch countdown scenario. The simulated countdown clock started Saturday night at 9 p.m. with reactant loading of Discovery's power reactant storage and distribution system and culminated with a planned ground launch sequencer (GLS) cut-off at T-31 seconds today at 4:50 p.m.

Cryogenic loading of the SLWT liquid hydrogen tank began at about 7:20 a.m. today and loading of the liquid oxygen tank began at about 10 a.m. A SLWT data evaluation team with members from KSC, Johnson Space Center and Marshall Space Flight Center were primarily interested in the tension loads that would be placed on the new tank during fuel loading. The extremely cold cryogenic fuels can cause the external tank to shrink up to 1-inch in diameter and several inches in length. This shrinkage places a tension or "pinch" load on the external tank/solid rocket booster strut attach points located near the tank's aft dome. The data evaluation team began gathering "pinch" load data at the 7 percent full mark during liquid hydrogen tanking. Throughout the entire liquid hydrogen tanking process, the tension loads were well within the acceptable limits.

The SLWT data evaluation team completed their test objectives earlier than expected so the test team chose to move GLS cut-off up by about two hours. An orbiter data evaluation team also used the test scenario as an opportunity to check-out various orbiter systems. The KSC ice/debris inspection team conducted remote inspections of the external tank from firing room No. 1 throughout the test and performed an onsite inspection after the SLWT was 100 percent full and halfway through stable replenish. Though additional hands-on inspections will follow this week, preliminary reports show the external tank in excellent condition. Draining of the external tank concludes at about 7 p.m. tonight and boil-off should be complete tomorrow afternoon. Preliminary results from the data evaluation teams will be presented at tomorrow's STS-91 Flight Readiness Review, where the official launch date and time is expected to be announced.


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