The Mainichi answers some common questions readers may have about the Hitomi X-ray telescope satellite, which the Japan Aerospace Exploration Agency (JAXA) lost contact with in March.
Question: I heard that JAXA lost contact with the Hitomi satellite more than two weeks ago. What was the Hitomi's original mission?
Answer: Highly energetic cosmic phenomena such as black holes and exploding stars emit enormous amounts of X-rays. However, Earth-based observatories can't pick up the X-rays because the planet's atmosphere gets in the way. The Hitomi's mission was to use its position high above the Earth to get a clear picture of cosmic X-ray emissions, and get a better idea of the nature of our universe.
Q: So what's going on with the Hitomi now?
A: The satellite was launched on Feb. 17 this year, and was taking good observations. On March 26, however, the data link between the Hitomi and ground controllers was suddenly cut. According to U.S. military analysis, there are about 10 objects of varying size near the satellite -- objects that may be fragments of the Hitomi itself.
Q: What caused this?
A: We don't know for sure, but it's possible the satellite's attitude adjustment system malfunctioned and caused the attitude thrusters to fire mistakenly, putting the Hitomi into such an abrupt high-speed spin that it shed some of its components. JAXA had been performing a course correction about 50 minutes before the satellite went dark, so that could be related.
Q: Is it impossible for the Hitomi to get any X-ray observations now?
A: Even if some components are broken, if solar power can be restored the satellite might be able to collect observations. It is estimated that the Hitomi is rotating once every five seconds, so the solar panels aren't getting the constant exposure to sunlight they need to generate power. The satellite's design will cause the rotation to slow little by little, however, so JAXA is hoping that the Hitomi will be able to generate power again in some months' time. The agency's hopes are tempered, however, by the possibility that the solar panels or observation equipment is damaged.
Q: Will it be a big problem if the Hitomi can't carry out its mission?
A: Hopes were high across the astronomy community that the Hitomi would give us a glimpse of the growth of black holes and shed light on other mysteries of our universe. At present, there are no plans for a successor satellite, so losing the Hitomi would be a damaging blow to astronomy. (Answers by Shuichi Abe, Science & Environment News Department)