Station To Shuttle Power Transfer System
The Station-to-Shuttle Power Transfer System (SSPTS; pronounced spits) allowed a docked Space Shuttle to make use of power provided by the International Space Station's solar arrays. Use of this system reduced usage of a shuttle's on-board power-generating fuel cells, allowing it to stay docked to the space station for an additional four days.
SSPTS was a shuttle upgrade that replaced the Assembly Power Converter Unit (APCU) with a new device called the Power Transfer Unit (PTU). The APCU had the capacity to convert shuttle 28 VDC main bus power to 124 VDC compatible with ISS's 120 VDC power system. This was used in the initial construction of the space station to augment the power available from the Russian Zvezda service module. The PTU adds to this the capability to convert the 120 VDC supplied by the ISS to the orbiter's 28 VDC main bus power. It is capable of transferring up to eight kilowatts of power from the space station to the orbiter. With this upgrade both the shuttle and the ISS were able to use each other's power systems when needed, although it is not expected that the ISS will ever again require the use of an orbiter's power systems.
During mission STS-116, PMA-2 (at the forward end of the Harmony module) was rewired to allow for the use of the SSPTS. The first mission to make actual use of the system was STS-118 with Space Shuttle Endeavour.
Only Discovery and Endeavour were equipped with the SSPTS. Atlantis was not equipped with the SSPTS, so could only go on shorter length missions than the rest of the fleet.
Read more about this topic: Electrical System Of The International Space Station
Famous quotes containing the words station, shuttle, power, transfer and/or system:
“If you have any information or evidence regarding the O.J. Simpson case, press 2 now. If you are an expert in fields relating to the O.J. Simpson case and would like to offer your services, press 3 now. If you would like the address where you can send a letter of support to O.J. Simpson, press 1 now. If you are seeking legal representation from the law offices of Robert L. Shapiro, press 4 now.”
—Advertisement. Aired August 8, 1994 by Tom Snyder on TV station CNBC. Chicago Sun Times, p. 11 (July 24, 1994)
“And the shuttle never falters, but to draw an encouraging conclusion
From this would be considerable, too odd. Why not just
Breathe in with the courage of each day, recognizing yourself as one
Who must with difficulty get down from high places?”
—John Ashbery (b. 1927)
“Fortune, which has a great deal of power in other matters but especially in war, can bring about great changes in a situation through very slight forces.”
—Julius Caesar [Gaius Julius Caesar] (100–44 B.C.)
“No sociologist ... should think himself too good, even in his old age, to make tens of thousands of quite trivial computations in his head and perhaps for months at a time. One cannot with impunity try to transfer this task entirely to mechanical assistants if one wishes to figure something, even though the final result is often small indeed.”
—Max Weber (1864–1920)
“He could jazz up the map-reading class by having a full-size color photograph of Betty Grable in a bathing suit, with a co- ordinate grid system laid over it. The instructor could point to different parts of her and say, “Give me the co-ordinates.”... The Major could see every unit in the Army using his idea.... Hot dog!”
—Norman Mailer (b. 1923)