The SHuttle Expendable Rocket for Payload Augmentation ...

The SHuttle Expendable Rocket for Payload Augmentation

(SHERPA)

Aaron Rogers, Paul Gloyer, Randall Carlson, Steve Buckley

17th Annual AIAA/USU Conference on Small SatellitesSSC03-II-2

August 12th, 2003

17th Annual AIAA/USU Conference on Small Satellites

OverviewIntroduction

Mission Requirements

Description

CAPE

Team

Key component technologies

Configurations

Architecture Design

Summary


Operational need for responsive orbit transfer capabilityCurrently no capability for secondary payloadsSpace Test Program• Provides subsidized spaceflight for

DOD Space Experiments Review Board (DOD SERB) approved experiments

• Provides spaceflight for other DOD approved experiments on a cost-reimbursable basis

Introduction


Raise satellite from 350 km (190 nm) to 700 km (380 nm) in 57 degree inclined orbitMass Breakdown: • 56 kg (124 lbm) for SHERPA• 90 kg (198 lbm) for satellite/payload• 150-170 kg (330-375 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/secondRequired components• Lightweight, Restartable, and Controllable motor• Guidance, Navigation, and Control System• Satellite Bus System (Power, Thermal,

Communications)• Separation System

SHERPA Mission Requirements


SHERPA DescriptionLightweight orbit transfer system for small satellitesMeets 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 2005/6Goal to cost $1 million (production)

1 2 3 4 5

A

B

1 2 3 4 5

A

B


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)


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)


Hybrid Propulsion RocketPrimary propulsion modulePropellant: Nitrous Oxide (N2O) oxidizer and Plexiglas fuel• Nontoxic• Non-corrosive• Non-flammable• Safe (two inherent ignition inhibits)

– N2O feed valve AND igniter must actuate for motor operation

Motor assembly and 4 tanksBoost time less than hourParameters:• 50% Mass Fraction• Specific Impulse (Isp) of 260 sec

N2O Pressure Relief(2 PL)

Motor Case Inconel

Pyro Igniter(4 PL)

Hybrid Propulsion Module (HPM)

N2O Tank Titanium(4 PL)

Lightband Interface

N2O Flow Control Valve

Feed Manifold

Injector Assy

Payload Interface


Hall Effect ThrusterHall-effect thruster (HET) electric propulsion module• Utilizes inert xenon gas

Low thrust (12 mN – 16 mN)Throttleable systemHigh efficiency• Isp of 1000 – 1400 sec

Low power (300 W)Long duration orbit raisingContinuous thrusting


A c tu a to rs

M u l i t - p r o c e s s R T O S

G y r o s

A c c e le r o m e te r s

M is s io n D a ta L o a d

G u id a n c e

N a v ig a t io n

M P C 5 5 5 µ P

A n a lo g F i l te r in gS e r ia l I /O

S il ic o n P i lo t F l ig h t C o n tr o l S y s te m

A t t i tu d e D e te rm in a t io n

IS R s

C o n t ro l

G P SG P S

A c tu a to rs

M u l i t - p r o c e s s R T O S

G y r o s

A c c e le r o m e te r s

M is s io n D a ta L o a d

G u id a n c e

N a v ig a t io n

M P C 5 5 5 µ P

A n a lo g F i l te r in gS e r ia l I /O

S il ic o n P i lo t F l ig h t C o n tr o l S y s te m

A t t i tu d e D e te rm in a t io n

IS R s

C o n t ro l

G P SG P S

Light weight and flexible3 accelerometers, 3 gyros, GPSMicroprocessorFunctions• Host ADCS software• Update measurements from attitude

sensors• Propagate attitude knowledge• Orbit determination

Silicon Pilot

Guidance & Navigation System


Lightband Separation Systems

Payload Separation SystemLightweight (2 kg)Low-shock (< 300 G’s)Non-pyrotechnicPrecision separation springs sizable to impart variable separation velocityFully redundant switches and tensioners/de-tensionersCustomizable bolt pattern and mechanical interface of the upper and lower rings to adjoining vehiclesHalf the height of V-bands and 1/8th the cross sectional areaFlight heritage:• NASA Starshine-3 mission (2001)• 11 Lightbands are awaiting launch on several

Shuttle flights and EELV missions


Launched 1993

Planned Launch 2006

DeliveredSPASE

Satellite Bus Systems

STPSat-1

Systems engineering, analysis,mission planningComplete bus design• Modular support structure• Software• Communications• Short Duration Mission Avionics

(SDMA)Final SHERPA integration, test, flight packagingSpacecraft expertise:• Alexis, HETE-1 & -2, Terriers,

SPASE (not yet flown)• Dept. of Defense STPSat-1

Launched 1996

HETE


SHERPA Configurations


Simplest configuration—provides only propulsive capability, no other sub-systems presentPayload is an independent system responsible for directing the propulsion systemNo separation

Mark I SHERPA


Demonstration modelStand-alone satellite with all sub-systemsBoost another independent satelliteEither chemical or electrical propulsion (demo will be chemical)Could add deployable panels or booms depending on mission needsProvides boost and then separation

Mark II SHERPA


Battery Module(fits 2 to 3 battery packs)

Avionics Module

Battery Pack

ACS Thruster

Radio

Avionics Module

Avionics / VME Cage

Silicon Pilot

SpaceDev Propulsion Module w/ ~12” Lightband

Coarse Sun Sensor (6 total)

“Saddle Bag”Mounting Structure

Mark II – Chemical Hybrid


Mark II – Electrical

Busek Hall Thruster Propulsion Module w/ ~12” Lightband

Booms are 3.15m long, 7 segmentsRoot Hinge can be designed for sun trackingOrbit average power of 422 W sun pointing

Mark II-E requires much more power than Mark II-C due to Hall ThrusterLarge Deployable Thin Film Solar Panels are employed


Platform configuration for space experimentsDesigned 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 long-

duration powerBoth Chemical and Electrical versions available

Mark III SHERPA


SHERPA Avionics

Nano Core

VME Backplane

PC&T Processor(optional)

I/OBoards Expansion Boards

SolarArrays

BatteriesPayload

SeparationSystem

Payload

TxRx Propulsion Power

Interface (PPI)

AttitudeSensors

Silicon Pilot(GPS/INS)

Backdoor Serial Bus

PropulsionModule(Hybrid or Hall)

ACSModule

SHERPA Signal Block Diagram


PC&T

Processor(optional)

I/OBoards

SolarArrays

Batteries

PropulsionModule(Hybridor HET)

PayloadSeparation

System

Payload

Tx

Rx

Propulsion PowerInterface (PPI)

Silicon Pilot(GPS/INS)

Attitude Sensors

PC&T

Arbiter

Masters

Slaves

Ground Command

ACSModule

SHERPA Command & Control Hierarchy


ISS Keep Out Zone

1d 13h 5m400

1d 23h 42m500

2d 11h 47m600

4d 5h 53m790

3d 3h 1m700

1d 3h 11m300

0d 17h 53m200

Time∆V

Simulation (STK)

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 = 795.33 m/sΘ

β

α

rA

rB

z

SHERPA

ISS

Analytical Analysis


Target Orbit Delivery Capability

Increasing Payload Mass

17.2 kg

10 kg

80 kg

20 kg

30 kg

40 kg

50 kg60 kg70 kg

90 kg

Increasing Perigee

400 km

700 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


SHERPA provides new & necessary capabilityDemonstrates and flight qualifies innovative technology research and developmentProvides on-demand flexibility for wide range of payloads and missionsImproves space-asset responsiveness• Satellites stored on-orbit and moved when needed• Reconfigurable and maneuverable• Easily procured

Summary


AeroAstro, Inc.- Aaron Rogers: (617) 451-8630 x27

[email protected]

Air Force Research Laboratory, Space Vehicles Directorate (AFRL/VS) – Kirtland Air Force Base, NM

- Lt Randall Carlson: (505) [email protected]

- Steven Buckley (Northrop Grumman) : (505) [email protected]

Questions?

The SHuttle Expendable Rocket for Payload Augmentation ...

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