平成28（2016）年2月17日に打ち上げられたX線天文衛星「ひとみ」（ASTRO-H）は、3月26日（土）の運用開始時（午後4時40分頃）に衛星からの電波を正常に受信できず、その後も衛星の状態を確認できない状況が続いています。現時点で、通信不良の原因は不明ですが、短時間ではあるものの衛星からの電波を受信できたことから、引き続き衛星の復旧に努めております。
この衛星状態を受け、復旧及び原因調査に万全を期すため、本日、国立研究開発法人宇宙航空研究開発機構内に理事長を長とする対策本部を設置し、第1回会合を開催いたしました。ひとみの通信の復旧及び原因調査について全社的に取り組んでおります。対応状況、調査結果については随時お知らせいたします。
X線天文衛星「ひとみ」（ASTRO-H）の通信異常について
国立研究開発法人宇宙航空研究開発機構
http://www.jaxa.jp/press/2016/03/20160327_hitomi_j.html
「ひとみ」２体に分離か…「機能回復の可能性」
読売新聞
http://www.yomiuri.co.jp/science/20160401-OYT1T50158.html
宇宙航空研究開発機構（ＪＡＸＡ）は１日、正常な通信が途絶えているＸ線天文衛星「ひとみ」について、３月２６日午前１０時３７分頃に何らかのトラブルで破損し、少なくとも２体に分離した可能性が高いと発表した。
地球の上空には約１万７０００個の宇宙ごみ（デブリ）が確認されているが、それらは衝突していないとみられることから、「（原因が）衛星内にあるとの立場で究明に努める」（常田佐久ＪＡＸＡ理事）としている。
分離後の２６日午後４時４０分頃から通信が異常となったが、ひとみからとみられる電波はその後も地上に届いた。ＪＡＸＡは「衛星本体は残存し、機能が回復する可能性はある」とみて、通信の回復を目指す。６月以降に予定していた本格的な観測の開始が大幅に遅れるのは確実となった。
Japan loses contact with its newest astronomy satellite, Hitomi
It may have broken up, but no one knows for sure
by Loren Grush
http://www.theverge.com/2016/3/28/11317312/jaxa-hitomi-satellite-lost-communication-debris
The Japanese Aerospace Exploration Agency (JAXA) is trying to establish communication with its new X-ray astronomy satellite, after the probe stayed silent over the weekend. The satellite, named Hitomi, was supposed to start operating at 3:40AM ET on Saturday March 26th, but the spacecraft failed to communicate with Earth at that time.
JAXA says it isn’t sure what state the spacecraft is in, and there are fears that Hitomi may have broken apart in space. The US Joint Space Operations Center, responsible for tracking space debris, tweeted that five pieces of debris were spotted around the satellite at around 4:20AM ET on Saturday. (The time was later amended to 9:42PM ET on Friday, March 25th.) The center ultimately identified the event as a “breakup,” but did not indicate what may have caused the incident.
Additionally, Paul Maley, an observational astronomer in Arizona, reported seeing Hitomi rotating once every 10 seconds or so, suggesting that it has somehow been knocked into an unintended spin. A video of Maley’s, provided to National Geographic, seems to support the idea that the satellite is spinning rapidly. Hitomi appears to change brightness as it tumbles through the sky, an indication that it is rotating. “The fact that it is rotating with extreme variations in brightness indicates that it is not controlled and that some event caused it to begin its rotation,” Maley told National Geographic.
On Monday, JAXA said it had received a short signal from the satellite, but did not immediately provide any more details about the communication. An additional update from JAXA on Tuesday clarified that the agency had received two signals from Hitomi — one at 9AM ET and one at 11:30AM ET on March 28th. To figure out what state the spacecraft is in, JAXA is trying to track Hitomi with ground-based telescopes and radar. The telescopes have identified at least two objects where the satellite should be, and radar has identified one of the objects. The agency said it will continue to investigate and will provide updates when they are available.
The Hitomi satellite, also known as ASTRO-H, is designed to study turbulent and energetic space events throughout the Universe. To do this, the probe has a series of instruments that can observe energy wavelengths ranging from soft X-rays to soft Gamma Rays. These will allow Hitomi to get more information about supermassive black holes, neutron stars, and the formation of galaxy clusters.