Science and Technology News

Wednesday, May 14, 2014

DebriSat: data from Destruction

by Marshall Polk
Arnold Engineering Development Complex Public Affairs

5/13/2014 - ARNOLD AIR FORCE BASE, TENN. -- The space environment presents many hazards for satellites and spacecraft. One of the major hazards is hypervelocity impacts from uncontrolled man-made space debris.

The recent Hollywood blockbuster movie Gravity dramatizes a series of catastrophic events that could follow just such an impact. While the film represents a nearly impossible scenario, the threat of space debris is a real problem that is being investigated by several space flight organizations throughout the world.

Arnold Engineering Development Complex teamed with NASA, the U.S. Air Force Space and Missile Systems Center, the University of Florida and the Aerospace Corporation to perform a hypervelocity destructive impact test of a modern satellite to help scientists better understand the effects of space collisions. The satellite, called the DebriSat, was a non-functional, full-scale representation of a modern satellite. The satellite was designed and fabricated by the University of Florida and supplied to AEDC for destruction.

The test utilized AEDC's Range G light gas launcher, which is capable of firing projectiles over one pound at speeds of more than 15,500 miles per hour.

"AEDC was the only facility that could provide kinetic energy that was high enough to cause the catastrophic destruction of the satellite," said Dr. J.C. Liou from the NASA Orbital Debris Program Office.

The Range G launcher fires into a sealed test chamber that can be conditioned to simulate the low pressure environment of outer space. Destroying the satellite inside the chamber also allows the debris to be easily recovered for analysis.

"Inside the chamber we line the walls with foam to stop the debris fragments from impacting the sides of the tank," said David Woods, Range G installation engineer. "We call this debris recovery method 'soft-catch' since it prevents the debris from being further damaged by impacting the walls of the test chamber."

This is not the first destructive satellite test for AEDC. In 1992, the Department of Defense and AEDC performed the Satellite Orbital Debris Characterization Impact Test in the Range G. This test involved destroying a Navy Transit satellite built in the 1960s. The SOCIT test provided useful data for the DOD and NASA to develop orbital debris satellite breakup models. Unfortunately, many of the modern satellites in orbit are constructed differently than the transit satellite used in the SOCIT test.

"The breakup fragments from a modern satellite are very different from the breakup fragments of an older satellite," Liou said. "We saw this in the 2009 collision between the Iridium 33 satellite and the Cosmos 2251 satellite."

NASA's satellite breakup model described the fragments from the older Cosmos satellite well, but noticeable discrepancies were present in the breakup prediction of the more modern Iridium 33. The DebriSat test hopes to eliminate these discrepancies in the models and also provide experiment data that will benefit the orbital debris community.

In addition to the DebriSat, AEDC Range G also helped the DOD, NASA and the Aerospace Corporation perform hypervelocity impact experiments involving an upper stage of a launch vehicle dubbed "DebrisLV" and a spacecraft protection device commonly called a Whipple Shield. Cooperative work between AEDC and the test customers allowed these additional test articles to be installed for the two facility checkout runs prior to the DebriSat test.

"This was a great opportunity for both the AEDC ranges and the Debris community," said Air Force Project Manager 2nd Lt. Ben Hoff. "Establishing these relationships and understanding the communities' need can help us as a test facility provide important data collection opportunities that would have been wasted because we didn't understand the need."

AEDC test facilities try to avoid any damage to the test article, but for this test NASA came with the goal of complete destruction and the Range G was able to deliver on target.

"We are very happy about the outcome of the DebrisLV and DebriSat experiments," Liou said. "We were well above the necessary impact energy to have a catastrophic destruction of the DebriSat, which resulted in a very successful test."

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