The XRISM Spacecraft
XRISM (X-ray Imaging and Spectroscopy Mission) launched on Sept. 6, 2023, from Japan's Tanegashima Space Center. It is the seventh in a series of X-ray observatories developed and operated by Japan.
XRISM’s Resolve is an X-ray calorimeter spectrometer which is cooled to a fraction of a degree above absolute zero. This chilly temperature allows Resolve’s detectors to measure the slight amount of heat generated when each pixel absorbs a single X-ray photon. XRISM’s Xtend is an X-ray camera that can image a wide field of view. Each instrument is at the focus of an XMA (X-ray Mirror Assembly) designed and developed at NASA's Goddard Spaceflight Center in Greenbelt, Maryland.
artist's concept
Look inside XRISM to see its instruments
Resolve
Resolve is a microcalorimeter spectrometer developed in collaboration between JAXA and NASA. When an X-ray hits Resolve’s 6-by-6-pixel detector, its energy causes a tiny increase in temperature.
To measure such a minuscule increase and determine the X-ray’s energy, the detector needs to cool down to around 460 degrees below zero Fahrenheit (minus 270 Celsius), just a fraction of a degree above absolute zero. The instrument reaches its operating temperature after undergoing a multistage mechanical cooling process inside a container of liquid helium.
By collecting thousands or even millions of X-rays from a cosmic source, Resolve obtains high-resolution spectra of the object. Spectra are measurements of light’s intensity over a range of energies — the equivalent to colors of visible light. Astronomers use spectra to learn about the physical states, motions, and compositions of cosmic objects. Resolve performs spectroscopy for X-rays with energies ranging from 1,700 to 12,000 electron volts by measuring the energies of individual X-rays. (For comparison, visible light energies range from about 2 to 3 electron volts.)
NASA’s Goddard Space Flight Center
Xtend
XRISM’s second instrument, called Xtend, was developed by JAXA and Japanese universities. Xtend is an X-ray imager that performs simultaneous observations with Resolve.
Xtend uses X-ray charge-coupled devices to detect incoming light and gives XRISM one of the largest fields of view of any X-ray imaging satellite flown to date, observing an area about 60% larger than the average apparent size of a full moon.
X-ray Mirror Assembly
XRISM also carries two XMAs developed by NASA. The XMAs focus X-rays from celestial objects at low grazing incidence angles onto the detectors. Each XMA focuses light onto one of XRISM’s instruments. XRISM has two identical mirrors, one for each instrument.
Each XMA includes both a primary and a secondary mirror. Each mirror has four quadrants that contain 203 nested aluminum mirror segments, for a total of 1,624 segments in each XMA.
