'Hidden X-Ray Cosmos' To Be Studied By XRISM Mission

Space.com

Learn how the NASA/JAXA X-ray Imaging and Spectroscopy Mission (XRISM) will study the 'X-ray Cosmos' in this explainer from the Goddard Space Flight Center.   Credit: NASA/Goddard Space Flight Center.

Transcript

00:00 So X-rays really shows us that the universe is very energetic.

00:07 We find X-rays in jets, erupting from the centers of active galaxies.

00:15 We use them to measure the spin of black holes or supernova explosions.

00:23 It takes a powerful event to produce cosmic X-rays.

00:29 Sometimes people also call it the hot universe,

00:32 because when you have this gas in galaxy clusters or also around galaxies that you can see only in X-rays,

00:38 this gas is about 10 million to 100 million degrees,

00:41 which is so hot that this gas does not radiate in optical, does not radiate in infrared,

00:47 but it only radiates in X-rays.

00:49 To further understand these hottest regions, we need the next generation X-ray telescope.

00:58 The Japan Aerospace Exploration Agency, or JAXA,

01:02 is partnering with NASA and the European Space Agency

01:06 to launch the next generation X-ray space telescope.

01:11 The telescope, called KRISM, launches from the Tonigashima Space Center

01:19 at the southern end of Japan on an H-2A rocket.

01:25 The spacecraft weighs over 5,000 pounds, stands over 30 feet tall,

01:31 and will orbit approximately 340 miles above Earth.

01:35 We're familiar with the medical uses of X-rays.

01:41 X-ray light is energetic enough to pass through our skin.

01:45 Our calcium-dense bones absorb that light,

01:49 blocking it from reaching the detector and hitting the object.

01:53 Blocking it from reaching the detector and creating a shadow.

01:57 Luckily for us, X-rays from space don't make it through our atmosphere.

02:03 But what that does mean is that we have to send X-ray hunting missions

02:07 into orbit to detect this high-energy light.

02:11 KRISM also needs special kinds of mirrors,

02:17 which are built at NASA's Goddard Space Flight Center.

02:21 One type of the mirror is called a nested mirror.

02:24 It looks like a cross-section of an onion.

02:28 X-rays are so energetic, they fly right through typical mirrors.

02:40 For the visible light, we typically place the mirror like this,

02:44 so that light just bounces back.

02:46 But for the X-rays, this doesn't work,

02:49 so that we put the mirror like this,

02:52 so that X-rays just graze the surface of the shell.

02:57 When they strike mirrors at very shallow angles,

03:02 X-rays too can bounce.

03:04 And so we made it like a conical shell, like this,

03:11 then X-rays can be directed.

03:14 [Music]

03:19 KRISM has two instruments, each with their own mirror assembly.

03:24 One for imaging, called Xtend,

03:26 the other for spectroscopy, called Resolve.

03:30 JAXA built Xtend to provide KRISM with a wide field of view.

03:37 It can observe an area about 60% larger

03:42 than the average apparent size of the full moon.

03:45 NASA's Resolve instrument is a spectrometer

03:51 that splits X-ray light, like a prism,

03:54 so scientists can detect specific elements

03:57 present in the sources they're studying.

03:59 It uses a small 6x6 pixel detector,

04:03 called a microcalorimeter,

04:06 nestled in a refrigerator-sized container of liquid helium.

04:11 Resolve will measure the small temperature changes

04:15 caused when X-rays hit one of those pixels.

04:18 To track such small temperature changes,

04:21 Resolve's detectors must be kept extremely cold.

04:25 That liquid helium cryocooler

04:28 will keep the instrument at 0.05 degrees Kelvin.

04:33 It's so cold,

04:36 it is a fraction of a degree above absolute zero.

04:41 Heat is simply a product of moving atoms.

04:45 Keeping Resolve's detector that cold

04:48 means that the atoms barely move.

04:51 So there's very little thermal noise in the system.

04:55 It's what keeps these accurate measurements possible.

05:01 Each X-ray detected will help scientists pursue

05:05 many questions about the hottest regions of the cosmos.

05:09 What's happening in the extreme gravitational fields

05:13 around black holes?

05:16 Can we discover what is inside a neutron star?

05:26 How did some of the universe's largest structures,

05:30 like galaxy clusters, evolve?

05:34 In an optical telescope, you will just see galaxies everywhere.

05:38 If you look at this same cluster of galaxies in X-rays,

05:42 you will see actually a lot of gas.

05:44 And this gas constitutes actually most of the matter

05:47 in the cluster of the galaxies,

05:49 which is something extremely important to understand

05:52 because it means that most of the matter in the universe

05:55 is not in the form of planets or stars,

05:57 but it's really in the form of this gas.

06:00 But CRISM really has this capability of decomposing

06:04 this X-ray light in a way that's much, much more accurate

06:07 than what has ever been done before.

06:10 [Music]

06:13 [Music]

06:17 [Music]

06:20 (gentle music)

06:22 [MUSIC]

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