mission patch

What: Airborne observation of the Hayabusa Sample Return Capsule re-entry over Australia, using a wide array of imaging and spectrographic cameras.

When: June 13, 2010

Where: Australia

Why: Fast re-entry, similar to that of probes sent to Mars, and similar to natural meteors. Only the second flight test of a thermal protection system under such conditions, following the Stardust SRC entry in January of 2006.

Who: International team of scientists (NASA, JAXA, ...), set up on a research aircraft operated by NASA


Mission statement: A mission to help evaluate the performance of thermal protection systems of atmospheric entry vehicles returning to Earth at superorbital velocities.
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SCIENCE OBJECTIVES OF THE RE-ENTRY OBSERVATIONS

capsule

The Hayabusa sample return capsule, which contains the precious asteroid sample, is designed to survive the entry in tact. The sample is protected from the heat of entry by a thermal protection system. The re-entry will be a unique flight test of this system under conditions not seen before. The heat shield is ejected at the time of parachute deploy and will be recovered by JAXA to study how well the thermal protection system performed under the extreme Mars-like conditions of entry. Dr. Tetsuya Yamada of JAXA was formerly in charge of designing the Hayabusa Sample Return Capsule and is now tasked with the recovery of the heat shield.

What conditions will the capsule encounter upon entry?

NASA and JAXA are collaborating in measuring the physical conditions during entry, making the re-entry of Hayabusa's sample return capsule a system field test of a thermal protection system:

  • How will the surface of the SRC heat shield warm up during entry (total heat flux)?
  • What is intensity of air plasma emissions from the SRC bow shock during peak heating (origin of radiative heat flux)?
  • How will the heat shield cool by loosing carbon (detection of CN, C, H, paint signatures)?
  • What will be the actual entry trajectory and ballistic coefficient of the capsule?
  • How will radiation and debris from the main spacecraft affect the entry?
  • In what manner will the main spacecraft break upon entry?

This will only be the second such thermal protection system field test, following the Stardust Sample Return Capsule Entry in January of 2006. This entry will feature a differently shaped capsule, using a different heat shield material. The Hayabusa capsule will arrive at 12.2 km/s (measured at 200 km altitude) at about a -12 degree flight path angle (geodetic), so fast that heating is similar to that of Mars entries. The heat shield material is a carbon ablator, meaning it will loose some of its carbon to carry away the heat and help cool the surface.

Will the capsule's radiation stand out from that of the main bus?

portrait Dr. Peter Jenniskens, a meteor astronomer and the Principal Investigator of the NASA sponsored Hayabusa Re-Entry airborne observing campaign warns that it is not clear how well the capsule will stand out from the debris of the main spacecraft, which can not be diverted and will follow the capsule into Earth's atmosphere at a short distance. The capsule will enter just ahead of the bus and the bus may break into fragments that can catch up with the capsule in projection on the sky. According to Jenniskens: "The main spacecraft will likely steal the show early on, but the capsule is expected to persist to greater depth and shine prominently later in flight at the time of peak heating."

BACKGROUND: THE HAYABUSA MISSION

The Japanese Hayabusa mission intends to bring back for the first time a small sample from an asteroid that was visited in space. The asteroid is 25143 Itokawa. Itokawa is an S-class asteroid (refering to the way the asteroid's surface minerals reflects light from the Sun) and astronomers are eager to know what type of meteorite corresponds to such asteroids. The spacecraft Hayabusa arrived in the vicinity of Itokawa on September 12, 2005. It attempted to collect a sample from the surface on November 20, and again on November 25, 2005. It has since followed its own orbit around the Sun and is expected to return to Earth in June of 2010. As an engineering effort, the spacecraft has made great accomplishements. It has only two tasks remaining: return to Earth and safely deliver the asteroid sample.

Will Hayabusa make it back to Earth?

KawaguchiHayabusa project manager Dr. Junichiro Kawaguchi of JAXA warns that altough the project team was able to revive the explorer, it is still not in a healty condition. Hayabusa is limping back, but operators have high hopes that all goes as planned. [More here]

JAXA logo On international cooperation, Kawaguchi says: "We have established cooperative systems primarily with NASA, as well as with Australia and other countries, for such things as research on heat-resistant material, observation of the asteroid Itokawa with ground telescopes and radar prior to launch, and data receiving and tracking operations using deep space networks with large antennae. A joint team will be formed to analyze the samples from the asteroid."

Will the spacecraft carry a sample?

YanoWe won't know immediately. After recovery, the sample return capsule will be taken to Tokyo before it is opened to see if it contains a sample. Dr. Hajime Yano, the lead scientist responsible for the sample collection aparatus, and former JAXA team lead of past airborne campaigns, has high hopes for a successful sample collection. Yano is coordinating the effort to transport the capsule back to JAXA. [More here]



Further reading

  • Stardust SRC Entry observing campaign results
  • Abe S., Yano H., Fujita K., Yanagisawa T., Yamada T., Ishihara Y., Fujiwara A. (2004) "HAYABUSA" Re-entry Capsule Observations as a Hypervelocity Artificial Meteor". PASP
  • Kawaguchi J., Ishii N., Abe T., Yamada T., Inatani Y., 2008. Japanese entry/reentry capsules: Past, Present, and Future. Proceedings IPPW08. 6th International Planetary Probe Workshop (Atlanta, 2008).
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Curator: Peter Jenniskens
Responsible NASA Official: Jay H. Grinstead

Last update: March 24, 2010


Hosted by: The SETI Institute

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