August 20, 2003

SIRTF

Status   (processing notes)

The launch of NASA’s Space Infrared Telescope Facility (SIRTF) has been rescheduled to no earlier than Monday, Aug. 25, at 1:35:39 a.m. EDT.

Winter conditions in the southern hemisphere are bringing high wind and seas delaying the arrival of a tracking and instrumentation ship in the Indian Ocean that is mandatory to support launch. This ship is used to receive data from the Delta second stage. The progress of the ship toward its support location is being monitored. Weather conditions are gradually forecast to improve over the next few days. At this time, based on the current progress of the ship, it is possible that it will be on station in time to support a launch on Monday.

At Pad 17-B, loading of the storable propellants aboard the Boeing Delta second stage has been completed. Oxidizer loading was performed on Monday and loading of the fuel was done on Tuesday. Servicing of the SIRTF observatory with cryogenic liquid helium is currently scheduled to begin on Thursday morning.

SIRTF was rolled out of Hangar AE early on Sunday morning, Aug. 10, and hoisted atop the Boeing Delta II launch vehicle. Mechanical and electrical connections were established, and a spacecraft state of health check was performed.

The Flight Program Verification, an integrated test of the vehicle and the spacecraft, was completed on Aug. 12. The payload fairing was installed around SIRTF atop the rocket on Aug. 14. Ground support equipment was delivered to the launch pad on Aug. 15 in preparation for tomorrow’s cryogenic servicing activities.

SIRTF is the fourth and final element in NASA’s family of orbiting “Great Observatories.” All objects in the universe with temperatures above absolute zero (-460 F) emit some infrared radiation, or heat. Infrared wavelengths lie beyond the red portion of the visible spectrum and are invisible to the human eye. Most infrared light emitted by celestial objects is absorbed by Earth’s atmosphere. Scientists rely on orbiting telescopes such as SIRTF to capture data on celestial objects and phenomena that are too dim, distant or cool to study using ground-based telescopes or by other astronomical techniques.

Project management of SIRTF for NASA is by the Jet Propulsion Laboratory. The observatory was built for NASA by Lockheed Martin and Ball Aerospace.

The launch period extends to Sept. 17.

GP-B

Status   (processing notes)

In the Gravity Probe B hangar, verification of new flight and mission software on the spacecraft was downloaded and has been verified. This activity was completed on Aug. 2. The Compatibility Test Van (CTV), which contains equipment to simulate NASA’s ground network of tracking stations and the Tracking and Data Relay Satellite System completed testing with the spacecraft on Aug. 15. Testing of the spacecraft’s RF systems is under way this week.

Gravity Probe B arrived at Vandenberg Air Force Base on July 11 from the Lockheed Martin plant in Sunnyvale, Calif. It was taken to NASA spacecraft processing hanger 1610 located on North Vandenberg Air Force Base. The spacecraft was unloaded from its transporter, placed onto an assembly and test stand, and the soft shipping cover removed.

The erection of the Boeing Delta II launch vehicle at Space Launch Complex 2 is currently scheduled to begin on Sept. 15 with the erection of the first stage. Attachment of the nine strap-on solid rocket boosters in sets of three is scheduled for Sept. 17-19. The second stage is planned for mating atop the first stage on Sept. 22. Gravity Probe B will be transported from the spacecraft hangar to Space Launch Complex 2 on Oct. 29 and hoisted atop the second stage. The Delta II fairing will be installed around the spacecraft on Nov. 5 as part of final preparations for launch.

Gravity Probe B is a relativity experiment developed by NASA’s Marshall Space Flight Center, Stanford University and Lockheed Martin. The spacecraft will test two extraordinary predictions of Albert Einstein’s general theory of relativity that he advanced in 1916. Gravity Probe B consists of four sophisticated gyroscopes to be launched into a 400-mile-high orbit for a mission lasting 18 to 24 months.

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