11 June 2010

A University of Queensland (UQ) mechanical engineering lecturer is one of two Australian academics to join astronomers from NASA, the Japan Aerospace Exploration Agency (JAXA) and other organisations who will get a front row seat and a rare opportunity to study a spacecraft's targeted fiery descent through Earth's atmosphere.

UQ’s Professor Richard Morgan and Associate Professor David Buttsworth from the University of Southern Queensland (USQ) have been invited to make measurements of the re-entry which will mark the end of the spacecraft's seven-year journey to bring a sample of asteroid Itokawa back to Earth.

A Douglas DC-8 airborne laboratory, with Professor Richard Morgan and Associate Professor Buttsworth on board, departed from NASA’s Dryden Aircraft Operations Facility at Palmdale, California, carrying nearly 30 scientists and their instruments to Melbourne, Australia to make final preparations for the highly-anticipated return of JAXA's Hayabusa spacecraft. They arrived in Melbourne early this morning.

Hayabusa is expected to fall to Earth over a vast, unpopulated area of South Australia at approximately midnight locally, or 7 am PDT, on Sunday, June 13, 2010. Earlier this week, JAXA announced it successfully completed the guidance of the Hayabusa spacecraft, so that it will land in the Woomera Prohibited Area in Australia.

"Hayabusa is hurtling toward Earth at an immense speed, comparable to that of an asteroid impact," said Peter Jenniskens, the observation campaign's principal investigator and a scientist at NASA's Ames Research Center, Moffett Field, California, and the SETI Institute, Mountain View, California.

"The capsule that protects the asteroid sample will be only 2 km ahead of the rest of the spacecraft, which will break into numerous pieces, essentially making it a man-made meteor."

Jenniskens and the team of astronomers onboard the DC-8 will have their instruments secured near the plane's specialised windows. This, paired with their altitude of 12 km far above light pollution and clouds, will enable the scientists to study what happens when the spacecraft and sample return capsule heat up high in the atmosphere.

When Hayabusa reaches an altitude of 58 km, its heat shield will experience temperatures of more than 2,800 degrees Celcius, while the gas surrounding the capsule will reach 7,200 degrees Celcius -- hotter than the surface of the sun.

The team’s primary goal during the airborne mission is to study the Hayabusa capsule's re-entry to gain technological insight into the heat shield that designers and engineers can use while developing future exploration vehicles.

Because of Hayabusa's unique heat shield material, shape and the tremendous interplanetary re-entry speed of 12 km per second, scientists expect its descent will provide new, valuable information about heat shields for computer models of re-entry conditions. JAXA’s Hayabusa is expected to be the second fastest man-made object to return to Earth; NASA's Stardust sample return capsule set the record re-entry speed of 12.8 km per second in January 2006.

"The return of Hayabusa provides NASA and JAXA with a rare opportunity to monitor the performance of an atmospheric entry vehicle at speeds much higher than that of the space shuttle returning from low-Earth orbit," said Jay Grinstead, the observation campaign project manager and a research scientist at NASA Ames.

"The spectrum of the light emitted by the gas and surface at these extreme temperatures tells us about the physics and chemistry of atmospheric entry. Our vantage point onboard the DC-8 and the variety of instruments enable us to track the evolution of the spectrum and compare it to simulations used for design and analysis of entry systems."

The airborne observation team also will provide JAXA with data and images obtained during the flight to correlate with JAXA's ground optical and radio observations and assist in locating the capsule on Earth.

Since the breakup of the main spacecraft will be visible as well, scientists will use images of the debris to validate computer models astronomers use to predict how an object will fragment and disperse as it enters Earth’s atmosphere at these
high speeds.

UQ’s Dr Tim McIntyre (Physics) and Dr Ben Upcroft (Mechanical Engineering) are leading a group of postgraduate students to do ground-based field observations at Woomera and Coober Pedy.

The Coober Pedy group will use a spectrometer, which is used to measure the properties of light.

NASA astronomers made similar airborne studies from NASA's DC-8 flying observatory for the September 2008 re-entry of the European Space Agency's Automated Transfer Vehicle "Jules Verne," as well as the Stardust sample return re-entry airborne campaigns.

During those missions, NASA scientists studied the light emitted by the descending spacecraft, to better understand the mechanisms of atmospheric entry heats of natural and man-made objects.

The Hayabusa airborne observation campaign is supported by the In-Space Propulsion Technology Project in the Science Mission Directorate at NASA Headquarters, Washington.

Professor Morgan said hypersonic flow research was a longstanding speciality of UQ and through the novel use of short duration wind tunnel facilities, the extreme flow conditions experienced during re-entry could be simulated in the laboratory.

Recent collaborations with NASA on wind tunnel testing of radiating hypersonic flows led to the invitation to participate in the scientific observation of the Hayabusa re-entry.

Media: Professor David Mee, Head of the School of Mechanical and Mining Engineering at The University of Queensland, on +61 7 3365 4414; Kim Jensen at the Faculty of Engineering, Architecture and Information Technology on +61 7 3365 1107.