Astronomie - XARM Röntgen-Astronomie-Teleskop als Ersatz für Hitomi



NASA and JAXA to develop replacement X-ray astronomy telescope


WASHINGTON — NASA and the Japanese space agency JAXA will start work this spring on an orbiting X-ray astronomy telescope to replace one lost shortly after launch last year.

In a presentation to the Committee on Astronomy and Astrophysics of the National Academies March 28, Paul Hertz, director of NASA’s astrophysics division, said a formal start of the project known as the X-Ray Astronomy Recovery Mission (XARM) will take place shortly after the start of the new Japanese fiscal year April 1.

“We are moving forward with the X-Ray Astronomy Recovery Mission,” Hertz said. The mission, he said, was included in the Japanese government’s budget for the new fiscal year, pending approval by the country’s parliament, the Diet.


XARM is intended to be a replacement for Hitomi, an X-ray astronomy spacecraft launched by JAXA in February 2016 but which malfunctioned in orbit a month and a half later. An investigation determined a chain of errors in the spacecraft’s attitude control system, compounded by human error, caused the spacecraft to spin up and its solar panels to break off, depriving the spacecraft of power.

NASA’s contribution to XARM will be the same as Hitomi, a soft X-ray spectrometer instrument, Hertz said. “Our deal is to provide the same hardware that we provided last time. We’re doing a built-to-print” version of the instrument, he said.

A formal review of NASA’s role on XARM, called Key Decision Point B, is planned for June. “We will then officially establish the XARM project,” he said.

He did not disclose the cost of XARM for NASA, but in a presentation last summer suggested rebuilding the instrument would cost between $70 and 90 million, spread out from 2017 to 2021. That cost, he said then, could be accommodated with existing planned budgets for NASA’s astrophysics division without doing “grievous harm” to other programs.

One issue to be worked out with JAXA, Hertz indicated, is the data release policy for XARM. He said he considered it to be a “directed” mission, which would make data from the instrument immediately available to astronomers. This is in contrast to “competed” missions led by a principal investigator, who has an initial proprietary period to analyze the data before it is widely released. That approach is still being negotiated with the Japanese, he said.

Previous versions of the NASA-built X-ray spectrometer instrument flew on two previous JAXA spacecraft, one lost in a 2000 launch failure and another that suffered a helium leak shortly after a 2005 launch that prevented the instrument from working. Hertz, in his presentation, pronounced XARM as “charm.” “It does need some luck,” he said.

Quelle: SN


Update: 7.07.2017


JAXA, NASA approve replacement for failed Hitomi astronomy satellite

Artist’s concept of the failed Hitomi satellite. Credit: JAXA

The Japanese space agency is moving ahead with a smaller-scale X-ray astronomy satellite to replace the failed Hitomi observatory, which spun out of control about a month-and-a-half after its launch last year.

The X-ray Astronomy Recovery Mission, or XARM, could launch as soon as March 2021, filling a potential gap in astronomers’ X-ray vision of the universe, according to the Japan Aerospace Exploration Agency, or JAXA.

NASA has agreed to a junior partner in XARM — pronounced “charm” — and supply X-ray telescopes and a spectrometer instrument for the Japanese-led mission, according to Paul Hertz, directory of NASA’s astrophysics division.

The Japanese Diet approved spending on XARM for the Japanese government’s current fiscal year, which started in April, and officials are in the final stages of formally kicking off development of the mission, Hertz said in a recent interview with Spaceflight Now.

The Hitomi satellite failed in March 2016 after a series of attitude control problems caused the orbiting observatory to spin up and shed segments of its power-generating solar panels. Ground controllers lost contact with the satellite as it orbited more than 350 miles (575 kilometers) above Earth.

Astronomers viewed the roughly $400 million mission as a stepping stone between current flagship-class X-ray telescopes, like NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton, and an upgraded, more sensitive X-ray observatory called Athena due for launch in the late 2020s.

Hertz said XARM will not have the observing range of Hitomi, which carried four scientific instruments sensitive to a range of X-ray wavelengths and gamma-rays, exposing astronomers to the workings of some of the most extreme events and environments in the cosmos, such as black holes, neutron stars and the creation of galaxies in the distant, ancient universe.

XARM will instead carry replacements for Hitomi’s two lower-energy instruments — the Soft X-ray Imager and the Soft X-ray Spectrometer. Both instruments contain critical parts provided by NASA, and the spectrometer is primarily a U.S.-developed payload.

“The mission will not be a carbon copy (of Hitomi), but the NASA contribution will be a carbon copy,” Hertz said in an interview. “The XARM mission is going to have only two of the four instruments that Hitomi had. It will have the Soft X-ray Spectrometer and the Soft X-ray Imager. The latter is a JAXA instrument, but we provided the telescope for both of those.”

XARM will not need an extendable 20-foot (6-meter) boom like Hitomi, Hertz said, because it will fly without the hard X-ray instruments that needed the deployable arm. Hard X-rays are at the higher-energy, shorter-wavelength end of the spectrum of X-ray light.

“That makes it a simpler mission, so although our part will be built-to-print, there will obviously be some changes on the bus,” Hertz said.

The Soft X-ray Imager on XARM will also have improved resolution over the instrument on Hitomi, JAXA officials said.

JAXA managers said NASA’s NuSTAR telescope, which sees the universe in hard X-rays, could fill in for the missing high-energy instruments on XARM. The two observatories could conduct coordinated, tandem observations to help realize Hitomi’s original science objectives.

NASA will spend between $70 million and $90 million on its part of the XARM observatory, according to Hertz. Flight spares at NASA’s Goddard Space Flight Center from the original Hitomi development will help save some money, he said.

The European Space Agency is also a minor partner in Hitomi’s replacement mission.

A Japanese government document dated May 30 indicated JAXA would set up a project team and select a manufacturer for the XARM spacecraft within one year.

Quelle: SN

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