the experience of 22 years developing small satellites in south · pdf file ·...

3rd Nanosat Symposium 12th December 2011

The experience of 22 years developing small satellites in

South Africa Prof Herman Steyn

University of Stellenbosch

12th December 2011

“GreenSat”

Military space program 1980-1994

Included a launcher program

Produced test facilities (vacuum,

vibration, anechoic, acoustic, etc)

Satellite was not fully completed

when program stopped in 1994

University involvement defined in

1989 with “Kleinsat” (Smallsat) idea

Sponsorships for MSc at Univ of

Surrey in the UoSAT unit (1990/91)

Junior lecturer of Stb Univ send to

ISU in Japan (Kitakyushu in 1992) 3rd Nanosat Symposium

12th December 2011

SUNSAT Birth

Chair of Satellite Systems in 1990 –

Prof Garth Milne

Prof Schoonwinkel father of “Kleinsat”

idea joined Stb Univ 1993

SUNSAT student project in Elec Eng

department of Stb Univ started in 1992

Aims were to:

» Train engineers for SA space industry

» Challenge graduate students

» Inspire school kids in science

» Have international cooperation

» Get sponsorships from SA industry

3rd Nanosat Symposium

12th December 2011 3rd Nanosat Symposium

SUNSAT Project

Africa’s first indigenous (locally built) orbiting satellite

Satellite was designed and developed without any technology transfer help

Developed by graduate students and staff in period 1992-1998

First microsatellite (64kg) with SPOT-5 type 3-band multispectral resolution

3456 pixel pushbroom sensor giving a 52 km swath and 15 m GSD from 800 km

64 Mbyte SRAM disk with 40 Mb/s QPSK S-band data downlink capability

3-Axis stabilised with reaction wheels during imaging, passive gravity gradient


SUNSAT Launch

NASA Turbo-Rogue GPS and laser reflectors for occultation research

Free piggyback launch with Danish Oersted microsatellite and USA Argos satellite as primary payload

Launch 23/2/99 on Delta II USAF

Orbit altitude 640 to 850 km

Successfully commissioned in 3 months

Radio amateur payload was huge success (store & forward, voice repeater)

Orbital useful life almost 2 years, last contact made in January 2001

Possible collision with space debris or more probable a battery malfunction


SUNSAT Imaging


SUNSAT Hardware


SUNSAT Achievements

Schools outreach program reached about 30 000 children with electronic kits

More than 100 graduates were involved in the program (Masters & PhD degrees)

Over 90 journal and conference papers

Large participation by AMSAT community

Significant international contact » Germany: FG Magnetometer for SAFIR-2

» South Korea: 15m GSD imager for KITSAT-3

» Australia: Star imager & Boom for FEDSAT

» NASA USA: Atmospheric occultation and gravitational studies

Established an university spin-off company SunSpace, to exploit SUNSAT’s satellite technology commercially


Stellenbosch Satellite Eng Group

Sun Space and

Information Systems

System

Development and

Deployment

ESL Electrical and

Mechanical

Engineering

Teaching and

Research

Research and

Development

Stellenbosch

University

Strategic

Partners

Optics

ISSA

AISS

SAC

12th December 2011 Satellite Research US

SunSpace Partnership

Research support

» Space radiation testing & fault tolerant

design methods

» Propulsion/thermal/material analysis

» Formation flying/Constellation control

» Small GEO platforms

» Imaging applications/data handling

» ADCS algorithms/simulation support

Product development

» New ADCS sensors and actuators

» New OBC and MMU architectures

» Spaceborne GPS receiver

» Sunsat-2004 microsatellite bus

ESL Ground Station


Typical Masters Topics

Satellite Engineering:

An AIS for ship surveillance and tracking from a satellite

Development of an onboard computer for a nanosatellite

Low-power communications bus and protocol for a nanosatellite

An infra-red based earth horizon sensor for a LEO satellite

GPS based orbit propagation/estimation for a LEO satellite

A real time operating system and housekeeping software for a satellite

An attitude control system for a nanosatellite

Onboard image classification to grade images for downloading

An arcjet propulsion system for a nanosatellite

Integrated CMOS star tracker and MEMS inertial rate sensor

Visual approach and docking mechanism for a satellite pair


SS-3 Satellite Project

200 kg Minisatellite

Technology transfer training

650 km sun-sync orbit

Main imager payload:

» 6.5 meter/pixel

» 3 Spectral bands

3-Axis reaction wheel stabilised

Video view finder capability

Design and built in South Africa by SunSpace

Dnepr Launch in April 2007

Commissioned in 8 weeks

Still fully operational to date


SS-3 Hardware/Testing


SS-3 Imaging Example


SS3 - View Finder - Aden

12th December 2011

Sumbandila Satellite Project

83 kg Microsatellite for DST

» 505 km 9 am/pm sun-synchronous orbit

» 6.25 m GSD Imaging in 6 spectral bands

» Email Communication system for DOC

» Propulsion system for drag compensation

» Expected orbital life 5 years

Satellite build by SunSpace in 15 months

Stellenbosch University did project

management

20 Masters and 2 PhD students and 8

interns in satellite engineering trained

Launch 17 Sept 2009 @ 17h55:07 from

Baikonur Kazakstan on a Soyuz/Fregat



Sumbandila Imaging: FMC4 scanning with X & Y wheel

Pitch forward ≈ 13 deg Roll = required amount for off-track image target

Increase pitch rate to ≈ -0.6 deg/sec

Scan image for 34 sec at constant rate for a 60 km image strip through target

Stop at pitch ≈ -13 deg

Return to nadir pointing Pitch & roll = 0 deg


Image Data download: Target Tracking towards SAC

12th December 2011

Imaging Product Tokyo Haneda Airport Area (≈ 12 km x 8 km)


12th December 2011

Tsunami Damage Sendai 05/04/11 (rightside image)


12th December 2011

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000-1000

0

1000

2000

3000

4000

5000

6000

7000Decay of semimajor axis

Decay (

Mete

r)

Orbits since launch

X: 8732

Y: 3515

Propulsion: Orbit Maintenance

On 26th January 2010 the butane propulsion fired for a total of 75 sec to lift the orbit ≈ 250 m

On 9 to10th March 2010 a total of 20 x 30 sec firings was used to lift the orbit another ≈ 1650 m

On 27 to 30th April 2010 a total of 34 x 60 sec firings was used to lift the orbit another ≈ 5000 m

On 14 to 16th April 2011 a total of 20 x 60 sec firings was used to lift the orbit another ≈ 3250 m

Current orbit perigee and apogee: 498 x 502 km

250 m

1650 m

5000 m


3250 m

12th December 2011

ADCS Product Examples


12th December 2011

Satellite Imagers


12th December 2011

RSA EO Satellite Roadmap

ARM-C

- 2m5 GSD Panchromatic

- 5m GSD Multispectral

- 15m GSD Hyper spectral

ZA-004 Very High Resolution

- < 2m GSD MS

- < 5m GSD SAR

SumbandilaSat

- 6m25 GSD Multispectral

- 6m25 GSD Viewfinder SUNSAT

- 15m GSD Multispectral Mass

Performance


12th December 2011

Next SA Satellite(s) ARM Constellation


12th December 2011

MSMI Camera

Core innovative concept:

» Dissimilar sensors on focal plane of a

single telescope

– Multi-spectral (VNIR) and panchromatic

– Hyperspectral: VNIR & SWIR

– Video (Snap shot or real time motion)

» Included

– Selectable combinations of EO data for

storage/downloading

– On board mass memory & data

compression

– Bore sight motion detection to assist ADCS

» Compact & light for micro/mini-satellites

– More affordable revisits by small satellite

constellations


12th December 2011

Camera Components


12th December 2011

Mission Requirements

Track crop production for predicting final yield » about once every 10 days

=> Multi-spectral data

Provide statistical estimates of cultivated areas » especially small field sizes typical of developing

countries

» estimate population density

=> High resolution panchromatic data

Identify crop variety planted » using unique spectral signatures

=> Hyper-spectral data


12th December 2011

MSMI Imager: Baseline for ARM Constellation

200 channels

Hyper-spectral –

15m

1 Pan

chromatic

channel

= 2.5m 6 Multi-

Spectral

channels =

5m

Blue Green Red NIR SWIR 3rd Nanosat Symposium

12th December 2011

University CubeSat programs

CPUT / F’SATI program:

» ≈ 40 Master students working on

ZACube-1 and ZACube-2

» University of Stellenbosch

contributing the ADCS design

» Human capital development for

SA space engineering needs

Univ Stellenbosch FP7 project:

» Participant in European Union

FP7 “Deorbit Sail” project

» Develop an ADCS for a solar sail

3U Cubesat


12th December 2011

ZACube-2

Objective: Student satellite project

3U CubeSat - Matrix 5.2 Mpix colour camera - HF beacon for SANAE radar antenna calibration - UHF store/forward system - L-band transponder - Novel 3-axis ADCS

ADCS - 3-axis Nanowheels - CubeSense Sun & Earth sensor - 3-axis Torquerods - Passive aerodynamic control


12th December 2011

Questions ?


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