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Damaged Japanese Spacecraft Likely ‘Beyond Saving’

This may be the largest remaining piece of the space telescope Hitomi.

New observations suggest that Hitomi, Japan’s flagship X-ray telescope, is tumbling through space in ten or more pieces—and is likely unrecoverable.

“The available data now seem to indicate a real break-up rather than just “some” debris shedding,” writes satellite tracker Marco Langbroek. “If true, then Hitomi is beyond saving.”

The Japanese Aerospace Exploration Agency (JAXA) lost consistent contact with Hitomi (also known as ASTRO-H) on March 26. Early reports showed the spacecraft’s orbit had rapidly changed—and that it had then shed at least five pieces of debris, size unknown. Video footage captured from the ground revealed an object tumbling through space, an ominous observation consistent with the intermittent radio signals JAXA was still receiving from the spacecraft. Altogether, the evidence suggested that some sudden event had disabled Hitomi, which would have peered into the hearts of galaxies and studied the maelstrom of matter swirling around black holes.

Whether that event was some kind of onboard explosion (more probable), or a collision with space debris (less probable) is still unclear.

Now, new radar observations from the U.S. Joint Space Operations Center indicate that Hitomi has broken up into at least ten pieces, and that two of these pieces are very large indeed. Even more worryingly, the spacecraft has gone quiet, with Japan no longer receiving the intermittent trickles of signals thought to come from a tumbling Hitomi.

“Sadly, I now believe that the radio signals were the dying sighs of a fatally wounded ASTRO-H,” tweeted Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics. “As far as I know, JAXA hasn’t officially given up though!”

Those ten pieces were likely all present on March 26, when the first reports of debris from Hitomi came in, but they weren’t separated enough in space to be reliably observed.

Now, orbital data show that some of those pieces are on quickly decaying trajectories and will burn up in Earth’s atmosphere within a week or so, writes astrophysicist Peter Coles of Sussex University. Those fragments are small, the kinds of things a spacecraft could plausibly shed and still function.

The two largest fragments, however, suggest that whatever happened to Hitomi is probably a terminal event. Video footage shows that these fragments, now called piece A and piece L, are roughly the same size and are tumbling through space, with one flying about 7 minutes in front of the other.

Japanese Spacecraft Tumbling in Orbit (L Piece)

The first of those pieces, now called piece L, was captured on video last week and mistakenly thought to be the main body of Hitomi. But it’s not. New observations suggest the tumbling fragment is a large, dense piece of Hitomi—perhaps its extendable optical bench, where the spacecraft’s hard X-ray detectors are. An April 2 video from satellite tracker Paul Maley, taken on the ground in Arizona, suggest fragment L is still tumbling through space, flashing about once every 10 seconds.

Fragment A, which is now thought to be the bulk of Hitomi, is trailing piece L by several minutes. Maley’s video shows that A is flashing about once every second.

“It is spinning quite fast with bright flashes,” Maley describes, noting that fragment A is also visible with the unaided eye. “The only question is, what are the real identities of the objects in orbit? Given the brightness of the two that I have seen, one is most likely the primary payload, the other is something sizable but what it is I do not know.”

Pieces A and L are trailed by a third large-ish fragment called K, which is about 26 minutes behind the pair.

The whole situation is unfolding into a heartbreaking disaster for Japan and for astronomers, who’d hoped this attempt to put an X-ray observatory in orbit would be successful (to really see the universe in X-rays, you need a satellite above the Earth’s atmosphere). Since 2000, Japan has tried twice to operate a space-based X-ray telescope; the first crashed during launch, and the second suffered from a leaky helium tank. So, hopes were high for Hitomi, which launched on February 17, and means pupil of the eye.

It could take years for the spacecraft’s two largest fragments to re-enter Earth’s atmosphere, and it’s possible that bits of them could survive the plunge to our planet.

“They aren’t decaying fast, may be a few years before they reenter,” McDowell says. “But when they do we’ll be paying close attention.”

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