Transcript Astronomers Learn to Work in Space

Astronomers Learn
to
Work in Space
Technical Challenges
Detectors
Pointing and Stability
Data Storage
Contamination
Thermal Control
Background radiation
First Astronomy from
Space
V-2 Rocket
October 10, 1946
Ultraviolet spectrum of sun
340 nm – 240 nm
Bead entrance
UV film
Aerobee
X-ray and Gamma Ray
Detectors
Geiger counters
Proportional counters
Solid state detectors
Scintillation detectors
Explorer 11(1961)
X-ray and Gamma Ray
Imagers
Rotating Grating
Spark Chamber
Cerenkov counter
Grazing Incidence telescope
Rotating Grating
Spark Chamber
Small Astronomical
Satellites
Three unstabilized survey satellites
SAS A (Uhuru) – Rotating Grating
SAS B – spark chamber
SAS C tandem proportional counters
Grazing Incidence
Orbiting Solar Observatory
8 launches: 1962-1971
OSO 1
Wheel spun at 30 rpm
Solar pointing within 2-3 arc minutes
Dry lubricant used when possible; areas that
required oils were sealed
Passive temperature control using coatings
Optical and UV Detectors
Film
Photomultipliers
Vidicons
SEC Vidicons
IPCS
Digicons
CCDs
Balloons
Human Assisted Missions
Gemini – hand-held near UV spectrograph
Apollo – Spectrometer on moon
Skylab – ATM, Small UV spectrograph,
various X-ray experiments
Spartan
Spacelab
Airplanes
Orbiting Astronomical Observatory
OAO Pointing Systems
3 rate gyros + high trust jets to slow tumble at
launch <0.75o/s
3 wide-angle solar cells + gyros to orient satellite
to sun-line
8 10o solar cells to orient satellite within 0.25o
6 star trackers (f.o.v. =1o) set to pick up at least 3
stars no fainter than magnitude 2 within 15 arc sec
of predicted position
Bore-sight star tracker to 2arcsec
Fine rate gyros counteract drift
Electro-magnets interact with terrestrial field to
unload fine gyros with gas jets only a backup
Data Handling for OAO
Magnetic core memory 100 kbits
Analog data could be transmitted in real time only
40-foot dishes in Quito and Santiago
85-foot dish in Rosman, NC
Commands transmitted to stations and data
returned by teletype
Microwave link available between control station
at Goddard and Rosman
Automatic safe mode if commands discrepant
OAO Mirrors
OAO A: Standard quartz mirrors
OAO B: Be mirror
OAO C: Egg-crate quartz mirror
Infrared Observations
Detectors:
Bolometer
Solid state
Heterodyne
Survey Satellite:
IRAS (1983)
IRAS Focal Plane
Radio Astronomy Explorer
Two V antennas each with 229m
arms
37m dipole
1968: Earth orbiter
1973: Lunar orbiter