Astronomers Learn to Work in Space. Technical Challenges Detectors Pointing and Stability Data Storage Contamination Thermal Control Background radiation.

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