The last year has been the busiest so far for the ASC with several key activities happening in parallel and two important additions to the scope of the project.
The first of two Critical Design Reviews was passed successfully last August. This review focussed on the first and second releases of the ASC Data System and included both hardware and software. The first release includes the software needed to support the ground calibration of AXAF scheduled to start this November in the X-ray Calibration Facility (XRCF) at Marshall Space Flight Center. The first release was delivered to the XRCF on schedule in March with two software increments planned for August and September to allow for final adjustments. The release includes a secure network link between the XRCF and SAO in Cambridge to allow for the replication of data at both sites and access to raw and processed calibration data by the science analysis teams.
Work has begun in earnest on the second release planned for November which provides the software needed to interface with the Operations Control Center (OCC). This release includes the mission planning software, submission of the science plan as Observation Requests, receipt of telemetry and other data.
The second and final CDR is being held at the time of writing and covers the third and fourth releases of the Data System. Release 3 will contain all the software needed to support the NRA one year before launch and much of the portable analysis software for users, and Release 4 will include the final portable analysis software, science product verification and validation software and science monitoring and trends tools.
A major change in the scope of the project occurred in March of this year when NASA finalized a decision to relocate the AXAF Operations Control Center (OCC) from MSFC to SAO. The result of the change is that AXAF will be operated by SAO from the OCC located in Cambridge using the data system software and hardware currently being developed by MSFC. The Flight Operations Team (provided by TRW) will implement the mission operations in the OCC supported by a technical team from SAO, MSFC, CSC and TRW. The OCC development has progressed rapidly since March with a facility selected, facility design work near completion, and build-out in an existing building just beginning. The facility is scheduled for completion in October when the ground system software and hardware will be installed in time to support an integrated ground system test early in 1997.
A second important change of scope to the project was the addition of an Education and Outreach program to the ASC. The program will encompass the development and dissemination of material for public information and educational purposes about the AXAF mission, X-ray astronomy concepts and AXAF science results. Further details about this exciting new activity are provided in a follow-on article in this issue.
Two other highlights during the year included the intense preparation for the ground calibration through the development of a Calibration Test List data base containing all tests to be run during the calibration. The parameters in the data base are being supported through detailed end-to-end calibration modeling. The second key area has been the involvement of ASC staff with the Science Instrument teams as the instrument components have gone through the various phases of laboratory (subassembly) calibration leading to instrument delivery later this year. All subassembly data are being archived by the ASC and the results are being incorporated into the calibration planning and models.
The next year promises to be an exciting one with the AXAF ground calibration, the second and third releases of the data system, the completion of the OCC facility and the integration and initial ground system tests of the data system hardware and software.
Roger Brissenden