The SHuttle Expendable Rocket for Payload Augmentation (SHERPA)

Transcription

1 The SHuttle Expendable Rocket for Payload Augmentation (SHERPA) Aaron Rogers, Paul Gloyer, Randall Carlson, Steve Buckley SSC03-II-2 August 12 th, 2003

2 Overview Introduction Mission Requirements Description CAPE Team Key component technologies Configurations Architecture Design Summary

3 Introduction Operational need for responsive orbit transfer capability Currently no capability for secondary payloads Space Test Program Provides subsidized spaceflight for DOD Space Experiments Review Board (DOD SERB) approved experiments Provides spaceflight for other DOD approved experiments on a costreimbursable basis

4 SHERPA Mission Requirements Raise satellite from 350 km (190 nm) to 700 km (380 nm) in 57 degree inclined orbit Mass Breakdown: 56 kg (124 lbm) for SHERPA 90 kg (198 lbm) for satellite/payload kg ( lbm) total Dependent upon berth location in STS cargo bay (5 available positions) Comply with Shuttle & International Space Station safety requirements 1 degree plane change for re-contact avoidance Inhibits, fault-tolerance, material selection Total Delta-V of 240 meters/second Required components Lightweight, Restartable, and Controllable motor Guidance, Navigation, and Control System Satellite Bus System (Power, Thermal, Communications) Separation System

5 SHERPA Description Lightweight orbit transfer system for small satellites Meets needs of Space Test Program (STP) Could be secondary payload aboard Expendable Launch Vehicle (ELV) Current design utilizes Shuttle Hitchhiker Experiment Launch System (SHELS) Will utilize the Canister for All Payload Ejections (CAPE) Concept of Operations: Secondary payload manifest Ejection, loiter on orbit Perform orbit adjust using Hohmann transfer Separation from payload Collision/Clearance Avoidance Maneuver (CCAM) Rapid re-entry Goal to demonstrate in 2005/6 Goal to cost $1 million (production) B A

6 CAPE Design CAPE Canister All aluminum construction One piece design 22 id. X 52 Long EMI corners Extension Collar 22 id. X 2 long Allows for separation mechanism changes Endcap Mounting Brackets Mounting Plate Wire tie guides Inhibit Box SHERPA configuration approx. 34 kg (75 lbm)

7 SHERPA Team Hybrid Propulsion Rocket SpaceDev, Inc. (Poway, California) Hall Effect Thruster Busek Co. Inc. (Natick, Massachusetts) Guidance & Navigation System Avidyne Corporation (Lincoln, Massachusetts) Systems Engineering and Integration AeroAstro, Inc. (Ashburn, Virginia) Payload Separation System Planetary Systems Corporation (Silver Spring, Maryland)

8 Hybrid Propulsion Rocket Primary propulsion module Propellant: Nitrous Oxide (N 2 O) oxidizer and Plexiglas fuel Nontoxic Non-corrosive Non-flammable Safe (two inherent ignition inhibits) N 2 O feed valve AND igniter must actuate for motor operation Motor assembly and 4 tanks Boost time less than hour Parameters: 50% Mass Fraction Specific Impulse (Isp) of 260 sec Pyro Igniter (4 PL) Motor Case Inconel Injector Assy Lightband Interface Payload Interface N2O Flow Control Valve N2O Pressure Relief (2 PL) Feed Manifold N2O Tank Titanium (4 PL) Hybrid Propulsion Module (HPM)

9 Hall Effect Thruster Hall-effect thruster (HET) electric propulsion module Utilizes inert xenon gas Low thrust (12 mn 16 mn) Throttleable system High efficiency Isp of sec Low power (300 W) Long duration orbit raising Continuous thrusting

10 Guidance & Navigation System Silicon Pilot Light weight and flexible 3 accelerometers, 3 gyros, GPS Microprocessor Functions Host ADCS software Update measurements from attitude sensors Propagate attitude knowledge Orbit determination Mission Data Load GPS GPS A ccelerom eters Gyros S erial I/O A n a lo g F ilte rin g IS R s Navigation Attitude Determ ination Guidance Control Mulit-process RTOS MPC 555 µ P Silicon Pilot Flight Control System Actuators

11 Payload Separation System Lightweight (2 kg) Low-shock (< 300 G s) Non-pyrotechnic Precision separation springs sizable to impart variable separation velocity Fully redundant switches and tensioners/detensioners Customizable bolt pattern and mechanical interface of the upper and lower rings to adjoining vehicles Half the height of V-bands and 1/8th the cross sectional area Flight heritage: NASA Starshine-3 mission (2001) 11 Lightbands are awaiting launch on several Shuttle flights and EELV missions Lightband Separation Systems

12 Satellite Bus Systems Systems engineering, analysis, mission planning Complete bus design Modular support structure Software Communications Short Duration Mission Avionics (SDMA) Final SHERPA integration, test, flight packaging Spacecraft expertise: Alexis, HETE-1 & -2, Terriers, SPASE (not yet flown) Dept. of Defense STPSat-1 HETE Launched 1996 Launched 1993 SPASE Delivered STPSat-1 Planned Launch 2006

13 SHERPA Configurations

14 Mark I SHERPA Simplest configuration provides only propulsive capability, no other sub-systems present Payload is an independent system responsible for directing the propulsion system No separation

15 Mark II SHERPA Demonstration model Stand-alone satellite with all subsystems Boost another independent satellite Either chemical or electrical propulsion (demo will be chemical) Could add deployable panels or booms depending on mission needs Provides boost and then separation

16 Mark II Chemical Hybrid Radio Avionics Module Coarse Sun Sensor (6 total) SpaceDev Propulsion Module w/ ~12 Lightband Saddle Bag Mounting Structure Silicon Pilot Battery Pack Avionics / VME Cage ACS Thruster Battery Module (fits 2 to 3 battery packs) Avionics Module

17 Mark II Electrical Mark II-E requires much more power than Mark II-C due to Hall Thruster Large Deployable Thin Film Solar Panels are employed Busek Hall Thruster Propulsion Module w/ ~12 Lightband Booms are 3.15m long, 7 segments Root Hinge can be designed for sun tracking Orbit average power of 422 W sun pointing

18 Mark III SHERPA Platform configuration for space experiments Designed to provide flexible, responsive interface for many-different payloads and missions Provides on orbit support after orbit transfer Navigation, guidance, attitude control, and propulsion Can provide communications and longduration power Both Chemical and Electrical versions available

19 SHERPA Signal Block Diagram Solar Arrays Batteries Payload Payload Separation System Attitude Sensors Silicon Pilot (GPS/INS) ACS Module Propulsion Module (Hybrid or Hall) Tx Rx Nano Core PC&T Processor (optional) I/O Boards Propulsion Power Interface (PPI) Expansion Boards SHERPA Avionics VME Backplane Backdoor Serial Bus

20 Ground Command SHERPA Command & Control Hierarchy Rx Arbiter PC&T Masters PC&T Processor (optional) Silicon Pilot (GPS/INS) Tx I/O Boards Propulsion Power Interface (PPI) Attitude Sensors Slaves Solar Arrays Batteries Payload Separation System Payload Propulsion Module (Hybrid or HET) ACS Module

21 ISS Keep Out Zone NASA unofficial ISS Keep-Out Zone guideline (pending formal notice): No orbit translation activities until minimum stand-off position achieved Precession analysis for required on-orbit loiter time 2.8 nautical miles per ft/s of s/c V Max SHERPA V = m/s Analytical Analysis Simulation (STK) β r B α ISS Θ z r A SHERPA V Time d 17h 53m 1d 3h 11m 1d 13h 5m 1d 23h 42m 2d 11h 47m 3d 3h 1m 4d 5h 53m

22 Target Orbit Delivery Capability 10 kg 17.2 kg 20 kg Increasing Payload Mass 30 kg 40 kg 50 kg 60 kg 70 kg 80 kg 90 kg Increasing Perigee 700 km 400 km Vehicle V a function of stack mass (i.e. propellant loading, payload) Achievable orbits vary with V capability: 17.2 kg payload: 700 km x 700 km circular orbit 400 km x 4500 km HEO orbit 700 km x 3750 km HEO orbit 90 kg payload: 700 km x 700 km circular orbit 400 km x 1750 km HEO orbit 700 km x 1400 km HEO orbit

23 Summary SHERPA provides new & necessary capability Demonstrates and flight qualifies innovative technology research and development Provides on-demand flexibility for wide range of payloads and missions Improves space-asset responsiveness Satellites stored on-orbit and moved when needed Reconfigurable and maneuverable Easily procured

24 Questions? AeroAstro, Inc. - Aaron Rogers: (617) x27 Aaron.Rogers@AeroAstro.com Air Force Research Laboratory, Space Vehicles Directorate (AFRL/VS) Kirtland Air Force Base, NM - Lt Randall Carlson: (505) Randall.Carlson@Kirtland.af.mil - Steven Buckley (Northrop Grumman) : (505) Steven.Buckley@Kirtland.af.mil