Thor (launch vehicle)
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- See also: PGM-17 Thor
Thor was a space launch vehicle derived from the PGM-17 Thor Intermediate Range Ballistic Missile. The Thor rocket was the first in a large family of space launch vehicles -- the Delta rockets. Thor's descendants fly to this day as the Delta II and Delta IV.
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[edit] Origins and early history
The first space launch type of mission Thor was asked to perform was the testing of the Atlas reentry vehicle. For these three tests a Thor core stage was topped by a second stage named Able using the Aerojet AJ-10-40 engine from the Vanguard second stage. The first such launch, 116, was lost due to turbopump failure of the main engine. The recovery of the reentry vehicles on the succeeding two attempts were not successful. Three mice, one on each vehicle, died in these tests.[1]
The Able stage from the Atlas reentry vehicle tests was upgraded (to become the Able I) with a third stage consisting of an unguided Altair X-248 solid rocket motor. A Thor Able I was used in in an attempt to place the 84 lb (38 kg) Pioneer spacecraft into lunar orbit where it would take pictures of the lunar surface with a TV camera. The mission ended prematurely at 77 seconds after launch on August 17, 1958, due to a turbopump failure.
On June 22, 1960, a Thor-Able-Star launched the first Galactic Radiation and Background (GRAB) electronic intelligence (ELINT) satellite for the United States Navy. These now-declassified satellites, operated under a cover story of providing solar radiation data, included an electronics package to detect Soviet air defense radar signals. GRAB-1 was thus the world's first successful reconnaissance satellite, preceding the first Corona mission to return film (Discoverer 14 on August 18) by almost two months.
[edit] Thor and the Corona program
Thor formed the core of the Thor-Agena vehicle used to launch the early Corona (also known as "Keyhole" and "Discoverer") satellites from Vandenberg AFB.[2] These were the first photographic spy satellites, used for photographic surveillance of the Soviet Union, China and other areas. Thor-Agenas were used as launch vehicles for Corona satellites from June 1959 through May 1963.
[edit] Thor becomes Delta
A fourth modification to Thor for space launch purposes, the Thor-Delta, has proven to be the longest-lasting of all Thor-derived rockets. Members of the Delta rocket family derived from the Thor-Delta continue to launch satellites and space probes for the United States to this day.
[edit] Thrust Augmented Thor
The Thrust Augmented Thor, or TAT, was developed to handle the growing recon sats of the Corona program. It added three Castor solid rocket strapon boosters—each providing 53,000 lbf (236 kN) thrust—to the standard Thor core stage. The boosters were lit on the ground and jettisoned after burnout.
[edit] Long Tank Thor
- Tapered fuel tank changed to cylindrical.
- Both tanks lengthened.
- Core stage 14 feet (4.3 m) longer.
- 49,000 lb (22,000 kg) more propellant.
