The Spectacular Breakup of ATV: One Final Experiment

September 25, 2008
By Peter Jenniskens and Jason Hatton
SETI Institute (Jenniskens) and ESA/ESTEC (Hatton)

In early March 2008, the European Space Agency launched a new spacecraft called the Automated Transfer Vehicle (ATV). ATV is a bigger version of the Russian Progress, a re-supply ship for the International Space Station (ISS). ATV had a perfect launch and docked to ISS as planned. After delivering supplies, the craft was used as crew quarters, and at one point helped push ISS out of the way of a dangerous piece of orbital debris. On September 5, 2008, it was finally time to call an end to the mission and the ATV was undocked from the ISS, ready to enter Earth's atmosphere over the South Pacific Ocean. Lacking a heat shield to save weight, the craft will break up on reentry in a spectacular fireball.

Our team came in the picture relatively late in the game. It turned out that we were not the only ones who were fascinated by the fact that the 13-ton ATV would enter in a controlled manner with a speed of 4.7 miles (7.6 kilometers) per second. If we could use guidance from the ATV Control Center for latest trajectory updates, we thought it would be possible to position two research aircraft alongside the shallow entry trajectory and observe the breakup process in detail. There is no way to do this for natural fireballs, which appear at random in the sky and at unknown times. Fragmentation is the single most important phenomenon that determines the physical conditions in natural meteors.

ESA was supportive of our proposed mission. A documentation of the breakup process could help validate the models built to study how that fragmentation evolves in a series of disruptions of major components. At reentry into the atmosphere, ATV would execute one final experiment before the mission completion. Our experience with meteor spectroscopy carried the promise of perhaps being able to identify some of the fragments from their radiation signatures. The ATV-1 "Jules Verne" Multi-Instrument Aircraft Campaign was born.

A workshop was organized at NASA Ames Research Center to discuss how best to observe the ATV reentry, bringing observers and ATV mission managers together. It was decided to postpone the reentry by three weeks so that the reentry would happen at nighttime for best viewing conditions.

As in earlier multi-aircraft (MAC) missions, NASA Ames took the lead in organizing the effort. Two aircraft will participate in this campaign. One is NASA's DC-8 Airborne Laboratory, operated by the University of North Dakota (NSERC) and NASA Dryden Flight Research Center from the Dryden Aircraft Operations Center in Palmdale. The other aircraft is a privately owned Gulfstream V, operated by H211 LLC at NASA Ames Research Center. Together they make it possible to triangulate the important fragmentation events and measure their altitude in the atmosphere.

A large team of researchers from ESA, NASA, universities and private organizations will join in the mission, including a team from NASA's Orbital Debris Office at NASA Johnson Space Flight Center. ESA project manager Dr. Jason Hatton has organized the ESA effort, while program manager Dave Jordan of NASA Ames Research Center has coordinated the NASA effort. The logistics for some 36 researchers are coordinated by the SETI Institute. SETI Institute's meteor astronomer, Dr. Peter Jenniskens, is the mission scientist.

The reentry is expected in the early morning of September 29. The two aircraft will leave from NASA Ames and NASA Dryden in the evening of September 26 to a staging area on the island of Tahiti in French Polynesia. From there, the team will depart deeper into the south Pacific on the early morning of September 29. If all goes to plan, the reentry will take only about 4 minutes, during which all data need to be collected.

Observing the ATV reentry is challenging, requiring good planning and communications with the spacecraft operators. Past observation attempts have often been unsuccessful due to lack of good coordination or wrong instrument settings. One example is the reentry of MIR, which was not observed from two chartered private aircraft back in 2001. Instead, MIR was directed to enter closer to the staging area, and only those that stayed behind at the hotel in Fiji observed the MIR reentry.

Our efforts are supported by the ATV Control Center in Toulouse, France. We hope to receive last-minute updates on the reentry process to be able to position ourselves well along the reentry path. Predictions have been made of how bright ATV will be, just prior to breakup, and we hope that this will enable us to have our instruments correctly configured. It is still a challenge and we hope you will be rooting for us. This trip to Tahiti will be no honeymoon.

For more information on the mission, please visit our mission website at: http://atv.seti.org.