Encyclopedia Astronautica
2000.02.13 - STS-99 Mission Status Report #05


The first "flycast maneuver" trim burn was completed without a hitch by members of the Endeavour crew early Sunday. A little later, the Payload Operations Center reported that the Shuttle Radar Topography Mission had successfully mapped 7.64 million square miles as of very early Sunday morning.

The flycast maneuver is designed to reduce strain on the almost-200-foot mast extending from Endeavour's cargo bay. The orbiter, which flies tail-first during mapping operations, is moved to a nose-first attitude with the mast extending upward. A brief reaction control system pulse begins the maneuver. The mast deflects slightly backwards, then rebounds forward. As it reaches vertical, a stronger thrust is applied, arresting the mast's motion and increasing the orbiter's speed.

For this mission Endeavour is in a comparatively low orbit, and is slowed by the upper fringes of the Earth's atmosphere, which causes it to lose altitude. The crew will make daily flycast maneuver trim burns to keep the spacecraft in the proper altitude for mapping.

Endeavour's Red Team, Commander Kevin Kregel, and Mission Specialists Janet Kavandi and Gerhard Thiele, began their eight-hour sleep period shortly after the trim burn. Blue Team members went on duty at about 12:30 a.m. Sunday.

Working around the clock in the two shifts, crewmembers will map an area from 60 degrees north to 56 degrees south. The area includes all the southern continents except Antarctica, and northern continents south of a line from the southern tip of Greenland, southern Alaska and through St. Petersburg, Russia. The area includes about 95 percent of the Earth's population.

All of the orbiter's systems continue to function normally. Crewmembers and flight controllers in Houston continue to look at the cold gas jet on the end of the SRTM's outboard antenna. They are looking at consumption of propellant and the lack of thrust from that jet, designed to help maintain the attitude of the mast. The balky jet is having no impact on the mission's mapping activities.

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