STS-99 was a Space Shuttle Endeavour mission, that launched on February 11, 2000 from Kennedy Space Center, Florida. The primary objective of the mission was the Shuttle Radar Topography Mission (SRTM) project.


Number in parentheses indicates number of spaceflights by each individual prior to and including this mission.

Mission parameters

Mission highlights

The Shuttle Radar Topography Mission (SRTM) is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. Its objective is to obtain the most complete high-resolution digital topographic database of the Earth. SRTM consists of a specially modified radar system that will flew onboard the space shuttle during its 11-day mission. This radar system gathered around 8 terabytes of data to produce unrivaled 3-D images of the Earth's surface.

SRTM uses C-band and X-band interferometric synthetic aperture radar (IFSAR) to acquire topographic data of Earth's land mass (between 60°N and 56°S). It produces digital topographic map products which meet Interferometric Terrain Height Data (ITHD)-2 specifications (30 meter x 30 meter spatial sampling with 16 meter absolute vertical height accuracy, 10 meter relative vertical height accuracy and 20 meter absolute horizontal circular accuracy).

The result of the Shuttle Radar Topography Mission could be close to 1 trillion measurements of the Earth's topography. Besides contributing to the production of better maps, these measurements could lead to improved water drainage modeling, more realistic flight simulators, better locations for cell phone towers, and enhanced navigation safety.

The Shuttle Radar Topography Mission mast was deployed successfully to its full length, and the antenna was turned to its operation position. After a successful checkout of the radar systems, mapping began at 12:31 a.m., less than 12 hours after launch. Crewmembers, split into two shifts so they could work around the clock, began mapping an area from 60 degrees north to 56 degrees south. Data was sent to Jet Propulsion Laboratory for analysis and early indications showed the data to be of excellent quality.

Mapping proceeded fairly smoothly, but during an attitude-hold period for payload mapping during the second day of flight, it was determined that orbiter propellant usage had doubled from 0.07 to 0.15 % an hour. The increase was caused by a failure of the payload cold-gas thrust system that was used to offset the gravity gradient torque of the mast.

As a result of this failure, orbiter propellant was being used at a higher-than-planned rate to maintain the attitude of the vehicle. Measures to reduce the expenditure were evaluated and based on the analysis, enough propellant could be saved to complete the planned 9-day plus science mission.

The first of a series of "flycast" maneuvers during the mission was also made on the second day of flight. The flycast maneuver was designed to reduce strain on the almost 200 foot (60 m) mast extending from Endeavour’s cargo bay when adjustments to Endeavour’s orbit were needed.

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.

Radar data gathering concluded at 6:54 a.m. EST on the tenth day of flight after a final sweep across Australia. During 222 hours and 23 minutes of mapping, Endeavour’s radar images filled 332 high density tapes and covered 99.98 % of the planned mapping area - land between 60 degrees north latitude and 56 degrees south latitude - at least once and 94.6 % of it twice. Only about 80,000 square miles in scattered areas remained unimaged, most of them in North America and most already well mapped by other methods. Enough data was gathered to fill the equivalent of 20,000 CDs.

Also aboard Endeavour was a student experiment called EarthKAM, which took 2,715 digital photos during the mission through an overhead flight-deck window. The NASA-sponsored program lets middle school students select photo targets and receive the images via the Internet. The pictures are used in classroom projects on Earth science, geography, mathematics and space science. More than 75 middle schools around the world participated in the experiment, which set a record. On four previous flights combined, EarthKAM sent down a total of 2,018 images.

Endeavour also saw the recommissioning of the Spacelab Pallet system, used for experiments in vacuum.

The 2007 documentary Oasis Earth contains HD video of the mission from inside the shuttle Endeavour, including many views looking at the Earth below. For example, one highlight is Mamoru Mohri shooting video of the moon and Mount Fuji.

This was the last mission to fly with the standard cockpit in 18 straight years. A glass cockpit was first used after this mission.(STS-101)

See also

External links

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