Science instruments for the Advanced X-Ray Astrophysics Facility (AXAF)

The AXAF program has undergone major changes since the Announcement of Opportunity was extended by NASA Headquarters in 1983. The science instruments (SI's) for AXAF have also experienced several design changes since they are competitively selected in 1985. Moreover, two separate complementary missions are now being baselined for AXAF; one is designated AXAF-I for imaging and will include the high precision Wolter type I optics, and the other is called AXAF-S for spectroscopy. Furthermore, on-orbit servicing has been eliminated from the program, and mission lifetime has been reduced. The resulting less-costly AXAF will still be superior to any previous x-ray observatories. Both missions continue to be managed for NASA through the Observatory Projects Office (OPO) at the Marshall Space Flight Center (MSFC). AXAF-I contains two focal plane SI's, the high resolution camera (HRC), and the AXAF charge-coupled device (CCD) imaging spectrometer (ACIS), as well as the high-energy transmission grating spectrometer (HETGS) and the low-energy transmission grating spectrometer (LETGS). AXAF-I launch is scheduled for September 1998.