www.sron.nl/telis-eos-missions-0-130/telis-sir-channel-eos-missions-0-1152/117-missions/missions.html

TELIS-SIR channel

ASTRO-H

SRON is participating in the Japanese ASTRO-H mission. This mission shall use observations of cosmic X-rays to study collapsing material in the vicinity of black holes, turbulences in clusters of galaxies, the shockwaves caused by supernova explosions and large-scale structures in the universe. Dark matter and the acceleration of cosmic particles to high energies shall also be investigated during the mission. SRON is supplying crucial technology for the Soft X-ray Spectrometer (SXS) of ASTRO-H. This spectrometer shall be the first instrument to simultaneously provide maps and extremely accurate spectra of clusters of galaxies and the remains of supernovas.

The Soft X-ray Spectrometer will be built by the Japanese space agency JAXA/ISAS in collaboration with NASA/GSFC, with contributions from Europe. The planned launch date for ASTRO-H is in 2014.

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Technology

Introduction hot universe

At the end of their lives, stars can eject a significant part of their mass to their surroundings by means of a supernova explosion or in a more gradual manner. This can lead to the formation of a compact object such as a white dwarf, neutron star or black hole. In the centre of the Milky Way galaxies, black holes can expand into quasars. All of these objects emit large quantities of energy in the form of X-rays or even energy-richer gamma radiation. Hot gas also exists within Milky Way galaxies, between the Milky Way galaxies in groups and clusters, and in the largest structure of the universe itself: the cosmic web. All of this gas also emits X-rays and gamma radiation.

X-rays and gamma radiation can only be observed from outer space as the Earth’s atmosphere blocks this radiation. However, that is far from easy as most of this radiation cannot be focussed using lenses or mirrors. Only soft X-rays can be reflected, but only if the radiation falls obliquely at a small angle on the reflecting mirror.

X-ray and gamma radiation
Within the area of X-rays, SRON has worked since 1990 on the development of three satellites: BeppoSAX, Chandra and XMM-Newton. For all three, SRON was the Principal Investigator for the development and construction of an instrument. Additionally, SRON is involved in the operation of the ESA satellite Integral, which measures gamma radiation. In all of these missions SRON is also active in the processing and interpretation of the data that the instruments provide.

On the Dutch-Italian satellite BeppoSAX there were two X-ray cameras that SRON had developed to image variable X-ray sources over a longer period of time. These cameras had a particularly large visual field of 40 by 40 degrees and played a key role in ascertaining the origin of gamma flashes.

Spectrometers
The NASA satellite Chandra and ESA satellite XMM-Newton both contain a spectrometer. Measurements of X-ray spectra provide important information about the conditions under which the radiation arose. For rapidly rotating objects, the 'red shift' and the 'blue shift' can be used to determine the speed of rotation. The spectrum also provides information about the composition of the material emitting the radiation.

For Chandra, SRON was responsible for the development of a grating, the central part of an X-ray spectrometer, which ensures the unravelling of the radiation according to wavelength. For XMM-Newton, SRON was mainly responsible for the development and construction of an entire spectrometer.

XEUS
For future missions such as XEUS, SRON is working on a new type of detector for X-rays, the microcalorimeter. The detector is able to precisely determine the energy of each photon captured and can perform spectroscopy without a grating. At the same time the calorimeter serves as a detector to produce sharp images. For the eventual production instrument, the aim is to place more than one thousand microcalorimeters on a chip.