Chandra X-ray Observatory

Chandra X-ray Observatory

Illustration of Chandra
Names	Advanced X-ray Astrophysics Facility (AXAF)
Mission type	X-ray astronomy
Operator	NASA / SAO / CXC
COSPAR ID	1999-040B
SATCAT no.	25867
Website	https://chandra.harvard.edu/
Mission duration	Planned: 5 years Elapsed: 25 years, 9 months, 5 days
Spacecraft properties
Manufacturer	TRW Inc.
Launch mass	5,860 kg (12,930 lb)[1]
Dry mass	4,790 kg (10,560 lb)[1]
Dimensions	Deployed: 13.8 × 19.5 m (45.3 × 64.0 ft)[2] Stowed: 11.8 × 4.3 m (38.7 × 14.0 ft)[1]
Power	2,350 W[2]
Start of mission
Launch date	July 23, 1999, 04:30:59.984 (1999-07-23UTC04:30:59) UTC[3]
Rocket	Space Shuttle Columbia (STS-93)
Launch site	Kennedy, LC-39B
Orbital parameters
Reference system	Geocentric
Regime	Highly elliptical
Semi-major axis	80,795.9 km (50,204.2 mi)
Eccentricity	0.743972
Perigee altitude	14,307.9 km (8,890.5 mi)
Apogee altitude	134,527.6 km (83,591.6 mi)
Inclination	76.7156°
Period	3809.3 min
RAAN	305.3107°
Argument of perigee	267.2574°
Mean anomaly	0.3010°
Mean motion	0.3780 rev/day
Epoch	September 4, 2015, 04:37:54 UTC[4]
Revolution no.	1358
Main telescope
Type	Wolter type 1[5]
Diameter	1.2 m (3.9 ft)[2]
Focal length	10.0 m (32.8 ft)[2]
Collecting area	0.04 m2 (0.43 sq ft)[2]
Wavelengths	X-ray: 0.12–12 nm (0.1–10 keV)[6]
Resolution	0.5 arcsec[2]
Instruments ACIS Advanced CCD Imaging Spectrometer HRC High Resolution Camera HETG High Energy Transmission Grating LETG Low Energy Transmission Grating
NASA Great Observatories ← Compton Spitzer → Large Strategic Science Missions Astrophysics Division ← Compton JWST →

The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the Space Shuttle Columbia during STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, enabled by the high angular resolution of its mirrors. Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes; therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64-hour orbit, and its mission is ongoing as of 2025^[update]. Chandra is one of the Great Observatories, along with the Hubble Space Telescope, Compton Gamma Ray Observatory (1991–2000), and the Spitzer Space Telescope (2003–2020). The telescope is named after the Nobel Prize-winning Indian-American astrophysicist Subrahmanyan Chandrasekhar.^[7] Its mission is similar to that of ESA's XMM-Newton spacecraft, also launched in 1999 but the two telescopes have different design foci, as Chandra has a much higher angular resolution and XMM-Newton higher spectroscopy throughput.

In response to a decrease in NASA funding in 2024 by the US Congress, Chandra is threatened with an early cancellation despite having more than a decade of operation left. The cancellation has been referred to as a potential "extinction-level" event for X-ray astronomy in the US.^{[citation needed]} A group of astronomers have put together a public outreach project to try to get enough American citizens to persuade the US Congress to provide enough funding to avoid early termination of the observatory.^[8]