Space Shuttle Relative Navigation Sensors Upgrade Jim Lamoreux NASA/JSC 5/22/02 Shuttle Rel Nav Sensors Upgrade Shuttle Relative Navigation Sensors for Rendezvous, Proximity Operations, & Docking: • Star Trackers (ST) • Ku-Band Rendezvous Radar (Integrated with TDRS Communication System) – Skin tracks 23 sq m target from 22 nmi; ISS from 100 nmi – Measures Rng, Doppler Rng Rate, Brg, Brg Rate • Trajectory Control Sensor (TCS) – Measures Rng, Rng Rate, Brg to retroreflectors on ISS for approach and docking • Hand-Held Lidar (HHL) – Rng, Rng Rate to skin reflection • Closed Circuit TV (CCTV) with subtended angle overlays • Crew Optical Alignment Sight (COAS) Shuttle Rel Nav Sensors Upgrade Shuttle Shuttle Sensor Sensor Management Management 40 nmi 2 ST RR 1 TCS 2 HHL 3 CCTV COAS Trang Le Alan Fox Sean O’Rourke Michele Kocen 22 nmi 8 nmi 3500 ft 100 ft 0 ft Shuttle Rel Nav Sensors Upgrade Typical Shuttle-ISS Rendezvous Profile Target -10 nmi -20 nmi -30 nmi NC4 Ti MC4 MC1 MC2 2 nmi MC3 Night Star Tracker Pass 4 nmi 6 nmi -40 nmi Day Star Tracker Pass Day Star Tracker Pass Sunset Begin Radar Tracking at 135 kft Sunset NCC Night Star Tracker Pass Shuttle Rel Nav Sensors Upgrade Shuttle-ISS Braking Gates and Proximity Operations Shuttle Rel Nav Sensors Upgrade Shuttle-ISS Separation and Fly-Around Shuttle Rel Nav Sensors Upgrade Rendezvous Sensor Priority Matrix Range Prime Sensor Backups >140,000 ft -Z Star Tracker -Y Star Tracker Wait for Radar <140,000 ft Day Radar -Z Star Tracker (while target < 8 arcmin) -Y Star Tracker (while target < 8 arcmin) COAS <140,000 ft Night Radar -Z Star Tracker -Y Star Tracker COAS Shuttle Rel Nav Sensors Upgrade Prox Ops Sensor Priority Matrix (ISS) Range Prime Sensor Backups 5000 - 600 ft TCS Radar HHL 600 - 3 ft TCS HHL CCTV and Overlay 3 ft - Dock TCS CCTV and Overlay Subtended angles charts (Visual) Shuttle Rel Nav Sensors Upgrade Prox Ops Sensor Priority Matrix (Non-ISS) Range Prime Sensor Backups 5000 - 100 ft or loss of lock Radar TCS (If available) HHL 250 (or Radar break lock) Grapple HHL TCS (If available) Camera Triangulation 35 ft - Grapple End Effector Camera TCS (If available) Camera Triangulation Subtended angles charts (Visual) Shuttle Rel Nav Sensors Upgrade • Ku-Band Radar/Comm System and TCS supportability problems are predicted due to a growing shortage of spare parts and unavailability due to obsolescence. Initial assessments (1999): • TCS not supportable beyond 2008, but parts available to built more units. • Ku-Band Radar/Comm System not supportable beyond 2005; Need to develop replacement. Shuttle Rel Nav Sensors Upgrade Initial Efforts for Ku-Band Radar/Comm Upgrade: • Employed QFD tool to identify and prioritize requirements. • • • • • • • • • Separate comm and radar systems for simultaneous use Eliminate antenna deployment (crit 1) Eliminate existing radar problems (e.g., range ambiguity beyond 22 nmi) and unused functions (e.g., angle rate measurement) Enhance sensor capabilities if cost effective Consider single sensor to replace rendezvous radar and TCS Employ dual redundancy to eliminate training and crew workload required for single-string radar failure. Obtained radar/lidar developer info via RFI’s and site visits, collaborated with JPL regarding lidar developments for automated rendezvous, docking, and landing for DS4 comet sample return. Established target costs and risks in design-to-cost exercise. Developed concept of operations, program and system requirements documents. Shuttle Rel Nav Sensors Upgrade • Architecture changed by Shuttle Program (8/01): • Abandon separate tracking and comm plan. • Functionally duplicate existing Ku-band integrated radar/comm system and retain legacy vehicle interfaces to minimize cost. • Radar upgrade terminated by Shuttle Program (2/02) • Reassessment of supportability problems, risks, and costs indicated problems are less severe and are manageable to at least 2012 if KSC repair capabilities are improved. • Business case no longer supports radar/comm upgrade. • Upgrade documentation archived for possible future use (COD, PRD, SRD, Specs, IDD, etc). Shuttle Rel Nav Sensors Upgrade Concluding Remarks • Information generated for Space Shuttle relative navigation sensor upgrade will be valuable for future vehicle developments. • For a new reusable launch vehicle, for which sensor interfaces are not already established, a single sensor type that can support rendezvous, proximity operations, docking/capture, and possibly landing may be attractive.