Forty years ago today — March 11, 1972 — the European TD-1A satellite launched from Vandenberg AFB atop a Thor-Delta rocket. The satellite’s “TD” designation was actually taken from the Thor-Delta launch system.
(TD-1A satellite. NASA image.)
TD-1A was Europe’s first three-axis-stabilized spacecraft, designed “to make a systematic sky survey in the ultraviolet and high-energy regions of the spectrum.” Two instruments pointed at the sun and measured its x-ray and gamma ray output; five other instruments scanned the sky to measure “ultraviolet, x and gamma rays, and heavy nuclei.”
More information on TD-1A is available on its page in the High Energy Astrophysics Science Archive Research Center.
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