Japanese-U.S. X-ray satellite launch postponed again

Artist's depiction of the Astro-E X-ray telescope

February 8, 2000
Web posted at: 11:19 p.m. EST (0419 GMT)

(CNN) -- Japan on Wednesday again postponed the launch of an observation satellite, this time because of a radar malfunction.

It was the second delay of the launch via M-5 rocket which was originally planned for 10:30 a.m. Tuesday (0130 GMT), said Yoshihisa Nemoto, a spokesman for the Institute of Space and Astronautical Science.

Tuesday's launch of the Astro-E research satellite was postponed because of bad weather. Nemoto said it has now been rescheduled for the same time Thursday from the Kagoshima Space Center in southwestern Japan.

The Astro-E spacecraft carries an X-ray sensor that can measure remote radiation levels ten times more precisely than its predecessors.

Besides showcasing an entirely new technology in X- ray detection, the Japanese-U.S. satellite observatory will earn the distinction of being the coldest known object in space.

"This new mission allows us to apply a piece of whiz-bang new technology to the exploration of the universe," said Dr. Alan N. Bunner, science director of NASA's Structure and Evolution of the Universe program.

The new instrument is the X-ray Spectrometer (XRS), developed jointly by NASA's Goddard Space Flight Center and Japan's Institute of Space and Astronautical Science.

The XRS measures the heat created by individual X-ray photons, as opposed to converting X-rays to electrical charges and then collecting that charge, which is the mechanism in other X-ray detectors.

To sense the heat of a single photon, the XRS detector must be cooled to an extremely low temperature, only 0.060 degrees Kelvin, or about -460 degrees Fahrenheit.

This condition essentially makes the XRS detector the coldest object in space. The absence of all heat, called absolute zero, is 0.0 degree Kelvin; the coldest reaches of space are a balmy 3 degrees Kelvin.

"This increased precision for measuring X-rays should allow fundamental breakthroughs in our understanding of essentially all types of X-ray emitting sources," said Dr. Richard Kelley, XRS principal investigator at Goddard, which is based in Greenbelt, Maryland.

Astro-E's targets include clusters of galaxies, supermassive black holes, neutron stars, supernova remnants, stellar coronae of stars 10,000 times more active than the Sun, and a study of how chemicals are made throughout the universe.

While the Chandra X-ray Observatory, launched in July, excels in producing X-ray images, Astro-E excels in producing spectra, or the "colors" of X-ray light. In this regard, Astro-E complements Chandra, analyzing the light that Chandra sees and determining the temperature, velocity and composition of the gas producing those X-rays.

Besides Astro-E and Chandra, the European X-ray Multi-Mirror Mission went into orbit in December. The flurry of launches is ushering in what many experts are calling the decade of X- ray astronomy.