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Is grief healthy? Now Chandra is dying

The malfunctions in NASA's telescopes are far from over

Chandra Space Telescope. Image: NASA
Chandra Space Telescope. Image: NASA
Avishai Gal-Yam

On Saturday, the astronauts aboard the space shuttle "Discovery" completed the general overhaul of the "Hubble" space telescope. In the eyes of many in the international astronomical community, the Hubble is the most important astronomical instrument today; The information produced from it in the last decade of its activity caused a veritable revolution in many fields and significant progress in the understanding of the universe. In addition to the possibility of observing farther than ever before and with unprecedented quality, the space telescope also contributed to the expansion of the astronomical community: it allowed relatively poor researchers (including Israelis) access to the most sophisticated telescope, an advantage that was previously reserved only for researchers at the rich and well-established universities.

The astronauts took off from the Kennedy space base in Florida, and after six days of flight they got the satellite on which the space telescope is installed in its orbit and captured it using a robotic arm. They then docked the telescope, which is as tall as a four-story building and weighs about twelve and a half tons, into the shuttle's hull. For about four days, the crew members performed three "space walks" - exits for activity in open space. Such an activity is necessary to carry out the repairs in the telescope.

The space telescope has been down for about a month due to a serious malfunction - a failure of four of the six gyroscopes installed in it. At least three working gyroscopes are required for the satellite to be able to determine its position in space, and to precisely aim the telescope and observe the desired targets. Shuttle crew members installed new gyroscopes on the telescope. Also, the central computer of the telescope was replaced with a stronger and faster model and additional repairs were made.

The supreme importance that the American space agency NASA attaches to the repair of the telescope is not only due to its scientific contribution. The telescope is also a key asset for the agency's public relations, helping to ensure continued public funding for its operations. The media frenzy won by NASA's skilled public relations personnel is an attempt to recover from the severe image blow it suffered due to the loss of the last two spacecraft launched to Mars. However, while the two lost spacecraft were considered "small" NASA projects - costing only about a quarter of a billion dollars - "Hubble" is one of the "big observatories" - projects that cost more than a billion dollars each.

Hubble is not the only large satellite observatory currently in orbit; In recent months, two more were launched - NASA's "Chandra" observatory (named after the Nobel Prize-winning astrophysicist Subramanian Chandraskar) and the European Space Agency's XMM satellite. In contrast to the space telescope named after the Hubble, which observes the universe in the wavelength range visible to the human eye and in the areas close to it - the infrared and the ultraviolet - Chandra and XMM are observing in the X-ray radiation range, also called X-rays. Research in the field of X-rays plays an important role in many areas of astronomy. An example of this is the study of the nuclei of active galaxies - galaxies in the center of which is a powerful radiation source, which according to the accepted assumption today is an extremely heavy black hole.

The launch of the "Chandra" observatory promised a real revolution in observations in the X field, therefore the relative silence of NASA's well-oiled public relations system when it comes to its achievements is puzzling. Those who delve deeper into the mountains of information distributed by NASA on the websites, and peruse the more humble parts of the scientific and technical documents, may be able to offer an explanation for this. Embarrassingly, about a month after "Chandra" was launched into space, a serious malfunction was discovered in some of the detectors installed in it. It turns out that every time the satellite passes through areas of space known as "radiation belts", which surround the Earth, eight out of ten detectors in one of the two central instruments installed in the observatory are damaged. When moving through the belts, the ability of the detectors, if they are working, to distinguish the energy of the X-rays hitting them is impaired. This is essentially the equivalent ability to distinguish between different colors of light; The detectors on the "Chandra" observatory become "color blind". By the time the fault was diagnosed, and during attempts to fix it, the detection ability of the detectors had deteriorated a hundredfold.

To prevent further damage, the satellite operators are forced to disable the detector at each pass through the radiation belt. The final damage caused to the observatory's scientific output due to the damage to the detectors and disruption of the planned observation program has not yet been estimated. Despite this, it is clear that such a serious malfunction in such a large-scale (and expensive) project may cause a lot of image damage to NASA. All this while on the other hand the competing European project (the satellite (XMM)) is being carried out, so far without any problems. Only in the future will it be possible to determine how the agency's recent failures have affected public opinion. The scientific community mostly hopes that NASA will continue to win public credit that will allow it to promote its research Space and the universe.

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