NASA > GSFC > Astrophysics Science Division > IXO
IXO is a facility-class observatory that will be directly inserted into an 800,000 km semi-major axis halo orbit around the Sun-Earth L2 libration point using either an Atlas V 551 or Ariane V launch vehicle. The mission design life is five years, with consumables sized for 10 years.
IXO is built around a ~3.3 m diameter grazing-incidence mirror assembly with a 20 m focal length. When deployed during the voyage to the L2 orbit, IXO will be ~23 m tall. The observatory is divided into four major assemblies or modules: the Spacecraft Module, Deployment Module, Optics Module, and Instrument Module. For more information, refer IXO Quick Reference Guide.
The Spacecraft Module (SM) accommodates the bulk of the spacecraft subsystems including the power, propulsion, radio frequency (RF) communications, guidance, navigation and control, and avionics. The electronics boxes, reaction wheels, and propulsion tanks mount to a nine-sided honeycomb deck. The 6.6 m × 3.3 m diameter cylindrical composite metering structure accommodates the solar arrays, thrusters, and high-gain antenna.
The Deployment Module (DM) is the portion of the metering structure which is extended on orbit. It consists of three identical ADAM masts, similar to those on NuSTAR. High precision deployment accuracy and repeatability was proven with the 60m ADAM masts used in space on SRTM. As the masts deploy, they pull with them wire harnesses and a pleated Whipple Shield type shroud assembly that shields the instruments thermally and from stray light, and provides effective protection against the micrometeoroids.
The Optics Module (OM) includes the Flight Mirror Assembly (FMA), deployable sunshade, and the star tracker/TADS periscope assembly. The Optics Module interfaces the Flight Mirror Assembly to the fixed metering structure.
The Instrument Module (IM) accommodates the instruments. All detectors except the XGS camera mount to the Moveable Instrument Platform (MIP), which is comparable to moving platforms on Chandra and ROSAT. Focus and translation mechanisms, coupled with a Chandra heritage Telescope Aspect Determination System (TADS) for flex body metrology, assure the centering of the detectors in the converging X-ray beam, and accurate attitude reconstruction.
The observatory design is well defined, building on studies performed over the last decade by NASA, ESA, and JAXA, and has strong heritage from previous spaceflight missions. Mission Performance Requirements are shown here. All are met or exceeded by IXO.