Aug.19, 1999 George T. Roach Integration Mission Design Center NASA- GSFC Code 543 Greenbelt, MD FAX

Overview See if the dual spacecraft MAXIM configuration can be accommodated on a single U.S. launch vehicle. Present a trade study comparing launch vehicles Present a concept that can meet mission requirements: - Launch and orbit configuration * Payload Instruments placements * Structural mass summary

Spacecraft Mechanical Overview The baseline will be 2 Mission Unique Spacecraft ( MUS): - Use of commercial parts and subsystems - Accommodate the Detector Instruments and Optic Instruments - Provide accommodations for a dual wing fixed solar array panels (total area= 6 meters ^2), for the detector spacecraft. - Provide accommodations for a fixed semi ring solar array panels (total area= 7 meters ^2), for the optic spacecraft. - The Optics spacecraft will interface to the Delta IV 5m dia. X 19.8 m long/ PAF - The core structure will be made-up of aluminum honeycomb panels, aluminum truss, fittings, brackets, diagonals and stringers. Note- Due to the time element in preparing this presentation, I baseline aluminum material, however due to the thermal sensitivity the structure material most likely would be composite. This would increase cost and fabrication complexity, but would decrease mass. In either case, this is do-able in the design. Mechanical Overview (continue) Spacecraft Description: The general shape is circle, cylindrical, square, rectangular, hexagonal, octagonal. The size is 4m by 3 m long. Interfaces to the launch via 3712 PAF, and is launch on DELTA The core structure will be made-up of aluminum honeycomb panels, truss, ring fitting, brackets, diagonals, and stringers. The spacecraft is considered an Open-Architecture-Configuration. ƀ The subsystems are mounted externally on structural members ƀ They are expose and cover with thermal blankets. The spacecraft is considered an Closed-Architecture-Configuration. ƀ The subsystems are mounted internally on structural members ƀ These subsystems are mounted shear panels, thrust tube or radials.

Launch Vehicle Trade Study Based on Performance to C3 = 0; Mass = 4100kg; Volume = 3.25 dia X 14.5 m Access Mode Candidates  No Foreign Launch Vehicles Investigated (Space Policy-buy American)  Delta II and III do not meet C3 performance requirements  Delta IV:  S,M, M+(4,2 &5,2 config.) do not meet C3 performance requirements  M+ (5,4) config. meets C3 performance requirements but does not meet fairing volume envelope  Heavy meets C3 performance requirements and fairing volume envelope  Atlas V:  Core and core plus 2 strap-on do not meet C3 performance requirements  Core plus 4 or 5 strap-on meet C3 performance requirements but does not meet fairing volume envelop for the 5m short or medium PLF  Heavy meets C3 performance requirements and fairing volume envelope  Lockheed Martin studying (via a KSC task) whether the stretched version of the medium PLF (5.4 m dia.X 26.5 m) can be used on the medium EELV launch vehicles (Results expected in a couple of months)  Boeing studying (via a KSC task) whether the heavy fairing (5 m dia. X 19.8 m) can be used on the medium EELV launch vehicles (Results expected in a couple of months)

Launch Vehicle Performance Baselined 8/18/99

For this study the Delta IV/5m/19.8m was baseline Launch vehicle will: Meet lift-off (mass) requirements +20% (actually approx.. 50%, as of 8/19 AM) Meets volume requirements LAUNCH VEHICLE

Delta IV (H) 5m diameter x 19.8m long Launch Fairing Removed Detector Spacecraft (2.2m) Optics Instruments (10m) Optic Spacecraft Systems (2.2m) Baffling LAUNCH CONFIGURATION 15.5 m 16.4 m Payload Spacecraft

ORBIT CONFIGURATION Optic Spacecraft Detector Spacecraft Solar Array (7 m^2, projected area)

Different views of the Optic space- craft Spacecraft sub- System This view the spacecraft subsystems removed OPTIC SPACECRAFT (DIFFERENT VIEWS)

This is the far end away from the detector spacecraft This is the viewing end toward the detector spacecraft Solar Array Propulsion Tanks (4) OPTIC SPACECRAFT (ON ORBIT)

Range lasers (4) Aspect Interferometer Walter Telescope Aspect Interferometer Walter Telescope Electronics X-Ray Interferometer OPTIC Instrument (rotated) OPTIC Instrument with support structure Note- The X-Ray Interferometer has been removed form clarity OPTIC INSTRUMENT

Stowed Orbit Payload Spacecraft Spacecraft Subsystems are mounted in this volume Fixed Solar Array (6m^2 shown) DETECTOR SPACECRAFT

Detector / CCD/ QC Cryogenics and Baffle Range Sensors and Baffle DETECTOR PAYLOAD INSTRUMENTS

Detector Baffle Range Sensors Range Sensors Baffle Detector / CCD/ QC Cryogenics Enlarged View of Baffle DETECTOR SPACECRAFT Payload Volume

TOP LEVEL SPACECRAFT BUS MASS SUMMARY Mass(kg)/per unit Total Mass(kg)

TOP LEVEL SPACECRAFT BUS MASS SUMMARY Mass(kg)/per unit Total Mass(kg) Amendment 8/20/99

SYSTEM LEVEL MASS SUMMARY (preliminary)

Conclusions: Mechanically this mission is feasible: - As of this phase of the study the dual spacecraft configuration can be accommodated on a single launch vehicle. * Using the Delta IV, DIV-H 5 m diameter x 19.8 m long fairing * Meets the minimum 20% mass margin * Meets the volume margin Launching two spacecraft always lower the frequencies due to the two separations, however with the extra mass margins you can increase the structural integrity of the structure by adding structural members and increasing cross sectional areas. The separation system between the Optic spacecraft and Detector spacecraft has yet to be worked out. This is not a trivial matter, I’m not aware of a 3 m + diameter marman ring at this time. Note- According with the Titan IV folks, anything that fit's inside this fairing the PAF can handle with reference to C.G. locations.