AFRL flies reentry experiments on Russian spacecraft heatshield

  • Published
  • By Pete Meltzer, Jr.
  • AFRL Materials & Manufacturing Directorate
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  The Air Force Research Laboratory, working with industry, evaluated the effectiveness of ground-based simulated atmospheric reentry testing using real-world experiments fitted onto a Russian spacecraft heatshield.

Scientists from the Materials & Manufacturing Directorate's Nonmetallic Materials Division, Composite & Hybrid Materials Branch, used four specially designed composite sample holders to evaluate a ground-based process known as arc jet testing, which simulates reentry by exposing materials to an extremely hot plasma flow.

Working within a narrow margin of opportunity, Dr. Keith B. Bowman and 1st Lt. William L. Heaner obtained U.S. Department of State and other approvals required to ship the fasteners and samples to Russia, where they were mounted onto an unmanned space capsule and placed into orbit, later to endure the rigors of atmospheric reentry. The experiments were flown at no cost to the United States and all the materials provided for the project were returned to the team for examination.

In May 2006, the European Space Agency (ESA) offered AFRL a unique opportunity to conduct in-flight material experiments on the Russian Foton-M3, an unmanned orbital reentry system introduced in 1985 and based on the Vostok spacecraft that carried renowned cosmonaut Yuri Gagarin, the first human to circle the globe, into orbit in 1961. The Foton-M3 carried a payload of more than 40 ESA experiments, including the AFRL experiments, and was launched into a 12-day orbit from the Baikonur Cosmodrome in Kazakhstan Sept. 14, 2007.

"Arc jet testing plays a vital role in the advancement of space technology," Heaner explained. "The purpose for AFRL supplying the sample holders to the ESA was to recover material samples for comparison to samples evaluated using ground-based arc jet testing.

"Each holder varied in material composition," Heaner continued. "This allowed us to test their individual performance as well as the performance of the four material samples during an actual reentry, and to evaluate the utility of the holders for future heatshield-mounted experiments." 

"The material samples provided by AFRL were flown as part of two ESA experiments called Stone-6 and Lithopanspermia," Dr. Bowman stated. "Stone-6 studies the physical, chemical, and biological modifications caused by extreme temperatures and pressures experienced during reentry in rocks coated with micro-organisms (cyanobacteria) or containing fossil micro-organisms. The Lithopanspermia experiment tests the hypothesis of interplanetary transport of micro-organisms (lichen) via meteorites," he said.

"The Stone-6 experiments flown on Foton-M3 consisted of three rock samples: cemented rock, basalt, and laminate. The Lithopanspermia experiment used granite. Each of the four rock samples was attached to the Foton-M3 space capsule's heatshield with its own holder," he said.

Results from in-flight testing indicated the organisms did not survive and one of the four holders was lost during reentry. However, the three remaining units proved to be more durable for reentry than the material holders used by the ESA and Roscosmos in previous flights, Dr. Bowman said.

"In addition to securing valuable scientific data about arc jet testing, the project has opened new opportunities for future joint ventures with the ESA and the Russian space program," he added.