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Six Decades of Guidance and Control Systems Experiences Henry Hoffman, Swales Aerospace Systems Engi

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Title: Six Decades of Guidance and Control Systems Experiences Henry Hoffman, Swales Aerospace Systems Engi


1
Six Decades of Guidance and Control Systems
Experiences Henry Hoffman, Swales
Aerospace Systems Engineering
Seminar December 5th, 2006
0
2
Objectives
0
  • Discuss key design development issues
    associated with guidance control systems
  • Discuss troubleshooting techniques to resolve
    guidance control anomalies
  • Discuss on-orbit satellite ACS troubleshooting
    techniques processes
  • Discuss on-orbit satellite ACS recovery
    techniques processes

3
1940s
0
  • WWII RADAR and fuses
  • Werner von Braun
  • Wind tunnels from Peenemünde

4
1950s
  • Angled arrow projectile/gun- launched guided
    missile (AAP/GLGM)
  • SUBROC development test
  • Explorer I (1/31/58)

R
5
1950s Explorer-1 Satellite
  • First US satellite Launched Jan. 31,1958 on
    modified Jupiter-C rocket by Army Ballistic
    Missile Agency
  • Spin-stabilized
  • Mass 14 kg.
  • Perigee 347 km.
  • Apogee 1,859 km
  • Inclination 33.2
  • Developed by Jet Propulsion Laboratory
  • Carried U.S.-IGY (International Geophysical Year)
    payload of James Van Allen
  • Resulted in discovery of radiation belts around
    Earth

6
1950s Explorer-1 Satellite (cont.)
Experienced On-Orbit Flat Spin Instability Issues
Flexible Whip Telemetry Antennas
R
7
1950s Explorer-1 Satellite (cont.)
  • Explorer-1 stability issues
  • Conservation of angular momentum applied
  • Designed to be spin-stabilized about its minimum
    inertia axis
  • Rotation of rigid body about either maximum or
    minimum inertia axis can be stable
  • Problem Explorer-1 not really a rigid body
  • Energy dissipation in flexible whip telemetry
    antennas had destabilizing effect
  • Resulted in flat spin state

8
Holy Grail of Satellite Dynamics
  • Conservation of momentum must hold
  • HI?K(constant)
  • Energy
  • E½ I?2
  • Emin½ (IMAX?min)?min ½ K?min
  • EMAX½ (Imin?MAX)?MAX ½ K?MAX

9
1960s Dawn of Satellite Era
  • Orbiting Geophysical Observatory (OGO-4)
  • Launch date July 28, 1967
  • Orbiting Astronomical Observatory (OAO-2)
  • Launch date Dec. 7,1968

R
10
1960s OGO-4
  • Mass 562 kg
  • Mission Conduct diversified geophysical
    experiments
  • Zero-momentum ACS
  • Problem Sun-induced thermal oscillations of
    60-ft.- long experiment antenna (floppy
    STEM-type) boom
  • Created attitude disturbance that ACS controller
    responded to by firing thrusters

11
1960s OAO-2
  • OAO science goals dictated stringent ACS
    requirements for pointing accuracy pointing
    stability
  • ACS for OAO-1 was gyroless zero-momentum design
    due to lack of confidence in gyro reliability
    (lifetime) for multi-year mission
  • Problem OAO-1 suffered catastrophic star tracker
    failure (high voltage arcing) entire mission
    was lost
  • ACS had total of 6 two-axis gimbaled star
    trackers
  • OAO-2 was equipped with inertial reference unit
    from MIT with high-precision gyros

12
1970s
IUE (1/26/78)
  • SMM (2/14/80)

RAE-B (6/10/73)
SSS (11/15/71)
R
13
1970s SSS
  • Small Scientific Satellite
  • a.k.a. Explorer-45 or S3
  • Spin-stabilized
  • Mass 52 kg
  • Inclination 3.2
  • Mission Study magnetosphere
  • Problem Thermal energy from sun deflected
    stiff radial booms at nutation frequency
  • Resulted in nutational instability
  • Demonstrated that this type of nutation
    instability is not limited to floppy booms
  • SSS essentially had energy source at nutation
    frequency
  • SSS nutation went away when spin axis moved close
    to sun
  • Maximum boom deflection, but minimum forcing
    function at nutation frequency

14
1970s SSS (cont.)
  • Fundamental nature of problem concerned thermal
    time constant of boom
  • Infinite time constant would mean no thermal
    bending at any frequency
  • Zero time constant would mean instantaneous
    thermal bending occurs in phase with motion
    relative to the sun (does not impact nutation)
  • If time constant is such that there is some mass
    motion phase shift at nutation frequency, there
    will be impact on nutation
  • Not just booms - could be any moving mass on
    spacecraft
  • Impact could be stabilizing or destabilizing
  • Similar nutation instabilities occurred on
    Ulysses spacecraft in 1990s

15
1970s RAE-B
  • Also known as Explorer 49
  • Mission Radio astronomy
  • Mass 328 kg
  • Orbit Lunar
  • Modified design of RAE-A to include bolt-on
    propulsion module needed for transfer orbit to
    Moon
  • Spin stabilized during transfer orbit to Moon
  • 750'-long booms attached to central body (1,500'
    tip-to-tip)

16
1970s RAE-B Schematic
LUNAR INSERTION MODULE
CENTER OF GRAVITY
VELOCITY CONTROL PROPULSION SYSTEM
R
17
1970s RAE-B (cont.)
  • Potential problem New bolt- on propulsion
    module mounted well below plane of spacecraft CG
  • Small principal axis misalignment would result in
    fluid transfer, causing further misalignment of
    maximum inertia axis away from geometric axis
  • Would have unfavorably impacted desired spin axis
    in transfer orbit (up to 15º from geometric spin
    axis)
  • Was discovered analytically by GSFC prior to
    launch

R -16
18
1970s RAE-B Propulsion Diagram
Solution Pinching off gas interconnect prevented
any significant fluid transfer Gas fuel
interconnects allow tanks to maintain equal
pressure on both tanks in spin stabilized mode
R -16
19
1970s IUE
  • International Ultraviolet Explorer (IUE)
  • Developed as GSFC in-house space science mission
  • Zero-momentum ACS
  • Mission Analyze ultraviolet light from stars
    blocked by Earths ozone layer
  • 3 year design life requirement, 5 year goal
  • July 1982 Down to 3 operating gyros from 6 (no
    spares)
  • Control scheme proposed that used FSS with any 2
    remaining gyros
  • Simulated, developed ready for operation by
    Spring 1983
  • Aug. 17, 1985 4th gyro failed, leaving
    spacecraft in safe hold mode with only 2
    functioning gyros
  • Upload of new 2-gyro control scheme was
    successful science operations resumed
  • Later, single gyro also fully tested on-orbit,
    but never required
  • Zero gyro case was also simulated (see SOHO)

R -12
20
1970s SMM
  • Solar Maximum Mission developed using MACS
    technology
  • Mass 2315 kg
  • Zero-momentum ACS
  • Low-Earth orbit (574 km)
  • Mission Study sun during high part of solar
    cycle
  • First spacecraft designed with on-orbit repair
    capability
  • By November 1980, a loss of reaction wheels
    (blown fuse) in satellites MACS module cut short
    original mission
  • GSFC developed magnetic control laws to maintain
    SMM in power thermally safe condition until it
    could be serviced
  • See 1980s slides for servicing mission details

R -12
21
1980s
TDRS-1 (4/5/83)
Ulysses (10/6/90)
COBE (11/18/89)
SMM Servicing (4/84)
R
22
1980s TDRS-1
  • Momentum-bias ACS
  • Used for relaying telemetry tracking from other
    space assets to ground, while not in view of
    ground station

23
1980s TDRS-1 (cont.)
  • Inertial (interim) Upper Stage (IUS) gimbaled
    nozzle failure caused stack to spin up to
    180º/sec
  • About 6 hours after launch, TDRS separated from
    IUS placed in stable inertial hold mode
  • Resulting orbit was highly elliptic (perigee
    several thousand miles low)
  • Operations further complicated when ground crew
    commanded TDRS into earth pointing mode, leading
    to excessive thruster firings, which overheated
    thrusters
  • Recovered orbit over 4 months with station
    keeping thrusters (39 ? V burns up to 180 min.)
  • 1 LBF thrusters used to de-spin, perform a total
    ? V of 1,000 fps to raise perigee 8,600 miles
    for 5,000-lb. spacecraft
  • Once 1 bad thing happens, take time to think
    about recovery BEFORE making another decision!

24
1980s SMM Servicing
  • Spin stabilized to 0.1/sec.
  • Shuttle mission 41-C (April 6, 1984)
  • George Pinkie Nelson attempted to grapple SMM
  • Original grapple device didnt work
  • Hand attempts to de-spin caused tumble that had
    to be recovered by ground before servicing EVA
    was successful
  • 10,000 LOC reloaded to get 6 LOC for Bdot
    control to de-tumble spacecraft
  • First satellite repair on-orbit
  • Mission completed December 1989

25
1980s COsmic Background Explorer (COBE)
  • Developed by GSFC to study residual radiation of
    Big Bang
  • Zero momentum ACS
  • Design philosophies
  • No single point failures
  • Autonomous safe hold
  • Fail operational
  • Fail operational philosophy used to prevent sun
    exposure of main science instrument dewar
  • Minutes of exposure would result in days of lost
    helium
  • Suffered gyro failure in 1st week of launch
  • Came up over horizon fully operational

26
1980s COsmic Background Explorer (COBE)
Dr. John Mather of GSFC
27
1980s Ulysses
  • ACS Spin-stabilized 5 rpm
  • Joint ESA-NASA mission in its 17th year of
    operation
  • Mission Explore polar regions of sun
  • Planned mission 10/1990 9/1995
  • Dimensions
  • Length (booms stowed) 3.2 m
  • Width 3.3 m
  • Height 2.1 m
  • Mass
  • Total spacecraft 370 kg
  • Scientific payload 55 kg
  • Propellant 33 kg

Only spacecraft in near solar-polar orbit
28
1980s Ulysses (cont.)
  • After launch, Ulysses operated normally in its
    cruise phase for about 1 month, with proper
    operation of passive nutation damper verified by
    sensor data
  • Problem Minutes after deployment of a 7.5-m
    axial boom antenna, Ulysses began unexpected
    nutation that grew to 7º peak-to-peak
  • When spacecraft operated CONSCAN earth tracking
    mode (using thrusters), nutation disappeared

29
1980s Ulysses (cont.)
  • Analysis predicted thermal deformation of boom at
    nutation frequency would cause nutation based
    upon Earth-spacecraft-sun angle (remember SSS?)
  • Based on JPL trajectory predictions spacecraft
    geometry, GSFC predicted boom would go into
    spacecraft shadow around Dec. 20
  • Henry stated that Santa Claus would fix to
    spacecraft before Christmas
  • Santa Claus prediction made a believer of ESA IG
    (chief engineer) Massimo Trella (See SOHO later)

30
1980s Ulysses (cont.)
  • Prime Mission
  • Oct. 1990-Sep. 1995
  • Jupiter flyby
  • Feb. 8, 1992
  • 1st extension
  • Oct. 1995-Dec. 2001

Ulysses Orbit Showing North South Solar Polar
Passes
31
1980s Ulysses (cont.)
  • 2nd extension
  • Jan. 2002-Sep. 2004

Ulysses Orbit Showing North South Solar Polar
Passes
32
1980s Ulysses (cont.)
  • 3rd extension
  • Oct. 2004-Mar. 2008

Nutation Occurs on this arc
Ulysses Orbit Showing North South Solar Polar
Passes
33
1990s
http//www.cira.colostate.edu/ramm/hillger/GOES-8-
12_image.jpg
GOES (4/13/94)
SOHO (12/2/95)
R
34
1990s GOES-I
  • 1st Loral series of geosynchronous weather
    satellites
  • Spacecraft acquisition managed by GSFC for NOAA
  • Momentum-biased ACS
  • Issue Loral safe-hold mode (SHM) was sun-
    pointing zero momentum on thrusters
  • Sensitive to earlier satellite losses due to
    control center inexperience
  • Not a forgiving SHM, unnecessarily throwing
    away momentum bias
  • Could achieve near-zero-momentum state but end up
    in tumble
  • GSFC directed a forgiving SHM without thrusters
    which retained momentum bias

35
1990s GOES-I (cont.)
  • Once GSFC SHM was implemented, on-orbit test were
    desired
  • Center director would not approve in-orbit SHM
    checkout of operational spacecraft
  • Henry gets his wish on a dark stormy night at
    230 a.m. on a weekend, when new software upload
    crashed flight computer ground commanded GOES
    to SHM
  • SHM was completely successful much more
    stressful than would have ever been permitted for
    checkout

36
1990s SOHO Overview
  • Solar and Heliospheric Observatory joint
    international collaboration between ESA NASA
  • Designed to study internal structure of sun
  • Launched 2 Dec. 1995
  • Mass
  • Total at launch 1850 kg
  • Payload 610 kg
  • Dimensions
  • Length with solar array deployed 9.5 m

37
1990s SOHO Reaction Wheel (Pre-launch) Story
  • 2 of 4 original RWAs failed in less than 1,000
    hours while on ground in Europe
  • Time to arrive on-station at Sun-Earth Lagrange
    point (L1) orbit was almost 2,000 hours
  • ESA planned only to rebuild 2 failed wheels
    others met spec
  • Direction from ESA IG (remember Massimo?) forced
    re-build of all wheels

38
1990s SOHO Orbit
  • SOHO slowly orbits L1
  • L1 point is about 1.5 million km away from Earth
    in direction of sun
  • From this vantage point, SOHO enjoys
    uninterrupted view of sun
  • Without rebuild of wheels, SOHO would probably
    have never attained L1
  • All wheels still working after more than 11 years
    on station

39
1990s SOHO Loss of Attitude Control in 1998
  • Control of spacecraft lost June 1998 due to
    cockpit error
  • Spacecraft in flat spin with no communication
    arrays on edge of sun
  • Restored 3 months later through efforts of SOHO
    recovery team
  • Recovery team had to defrost SOHO
  • 2 of 3 onboard gyroscopes never recovered 3rd
    failed, December 1998
  • GSFC proposed use of zero-gyro concept, 1st
    developed for IUE spacecraft
  • Flight software installed February 1999
  • Allowed spacecraft to return to full scientific
    operations

40
Lessons Learned
  • Conservation of momentum must hold !
  • If at all possible, join with Mother Nature,
    dont fight her
  • If at all possible, dont autonomously fire
    thrusters
  • In spin stabilized configuration, consider
    nutation as structural resonance of system (SSS
    Ulysses)
  • Look for disturbances at nutation frequency, not
    spin frequency
  • Safety reliability are opposing requirements
  • Be persistent! If something is not right, say so!
    (GOES SHM)
  • When accused, the key 1st step is denial (OGO-4)

41
Lessons Learned
  • Design philosophies
  • Design Backwards Start conceptual design of
    satellite ACS based on what is needed for
    on-orbit normal mode operations then move to
    launch
  • Reliability 3 Levels
  • No single point failures
  • Safe hold whether autonomous or by ground command
    must have ability to reconfigure around failure
    and resume mission after ground intervention
  • Fail operational
  • In real-time environment, once 1 bad thing
    happens, take time to think about recovery BEFORE
    making another decision!
  • Practice omphaloskepsis
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