Astronomers Learn to Work in Space
Dec 16, 2015
Astronomers Learn to
Work in Space
Technical ChallengesDetectors
Pointing and StabilityData Storage
ContaminationThermal Control
Background radiation
First Astronomy from Space
V-2 RocketOctober 10, 1946
Ultraviolet spectrum of sun340 nm – 240 nmBead entrance
UV film
Aerobee
X-ray and Gamma Ray Detectors
Geiger countersProportional countersSolid state detectorsScintillation detectors
Explorer 11(1961)
X-ray and Gamma Ray
ImagersRotating Grating Spark Chamber
Cerenkov counterGrazing 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 Observatory8 launches: 1962-1971
OSO 1
Wheel spun at 30 rpmSolar pointing within 2-3 arc minutes
Dry lubricant used when possible; areas thatrequired oils were sealed
Passive temperature control using coatings
Optical and UV DetectorsFilm
PhotomultipliersVidicons
SEC VidiconsIPCS
DigiconsCCDs
Balloons
Human Assisted MissionsGemini – 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 Systems3 rate gyros + high trust jets to slow tumble at
launch <0.75o/s3 wide-angle solar cells + gyros to orient satellite
to sun-line8 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 positionBore-sight star tracker to 2arcsec
Fine rate gyros counteract driftElectro-magnets interact with terrestrial field to
unload fine gyros with gas jets only a backup
Data Handling for OAO
Magnetic core memory 100 kbitsAnalog data could be transmitted in real time only
40-foot dishes in Quito and Santiago85-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:BolometerSolid state Heterodyne
Survey Satellite:IRAS (1983)
IRAS Focal Plane
Radio Astronomy Explorer
Two V antennas each with 229m arms
37m dipole
1968: Earth orbiter1973: Lunar orbiter