Instrument, Spacecraft, and Launch Overview

1. Instrument, Spacecraft, and Launch Overview Joan Howard Ball Aerospace

2. Instrument Requirements

4. Ball Heritage • Currently building SIRTF CTA and instrument which uses Ge:Ga FPA’s • Past CDR in subassembly test • No major technical showstoppers • IRAS flying successfully • very similar from a cryo design - only smaller • Conceptually simple design • simple electronics, tested FPA’s, small/few element optics, but…. • Cryo design never simple

5. Spacecraft Requirements • Low Cost - less than $15M? • Accept >125 kg instrument • Provide > 30 Watts of power to payload • Pointing Stability < 24 seconds per data acquistion • Fit into selected Launch Vehicle • Data Storage: 200 Mbytes

6. Spacecraft Key Performance Requirements Description X-12M SMEX LITE SA-200S MiniStar Spacecraft Bus Mass 65.6 kg 75kg 98kg Payload Mass Capability 200 kg 91kg 200kg 180kg Available Payload Power > 100 W 150W 60W 17.5W ACS Configuration 3-axis stabilized 3 axis zero momentum Gravity Gradient Attitude Knowledge 28 mrad 5mrad .5 degrees Attitude Control 32 mrad 96mrad 10 degrees Payload Data Storage 256 Mbytes 130 Mbytes 8Gbyte 3Mbytes Communications S-Band S-Band S-band S-band Telemetry Rate 4Mbps 2.25Mbps 10Mbps 1 Mbps

7. Equipment Shelf Provides Ample Area For Subsystem Units

8. S/C Selection • Meets minimum requirements • Lowest total cost • nearly all COTS buses will need changes • integration issues • heritage of performance: technical, cost, schedule • Willing to work with team • Selection not mandatory for 1st round - a solution, not the solution needed

9. Issues/risks/options • Need good story for aperture cover - esp. after WIRE • Light shade a key driver in itself and for cryo design • Star tracker vs. gyro • battery size vs. eclipse • CPU capabilities/memory - on orbit computation vs. downlink • configuration drivers: LV, COTS, star tracker location, timeline, launch date

10. Launch Options