Science Fair Project Encyclopedia
ISS Truss
The ISS Truss forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.
In the initial Space Station Freedom design, a variety of designs for the truss were used, all of them designed to be shipped up as girders where they would be assembled and their equipment installed by astronauts on spacewalks once it had been launched. After the 1991 redesign, NASA switched to shorter, prefabricated pieces that would require minimal installation.
The first truss piece to be launched, the Z1 truss, is a temporary mounting position for one of the solar arrays. It contains the control moment gyro (CMG) assemblies, electrical wiring, communications equipment, and two plasma contractors designed to neutralize the electrical charge of the space station.
The second truss piece to be launched is the P6 truss, which contains a solar array, radiators, and plumbing. It is currently mounted to the Z1 truss, but will eventually be moved to the port side main truss.
The port and starboard trusses attach to the S0 truss. The P1 and S1 trusses, to port and starboard sides of the S0 truss respectively, contain carts to transport the Canadarm 2 and astronauts to worksites and also contains radiators to dissipate heat. Going out to the port side, the P3 and P4 trusses together contain a pair of solar arrays, a radiator, and a rotary joint to better aim the solar arrays. The P5 truss provides a mounting for the P6 truss, once it has been moved off of the Z1 truss. Similarly, the S3, S4, S5 and S6 trusses provide two more pairs of solar arrays, more radiators, and another rotary joint.
Truss and Solar Array Assembly Sequence
| Element | Flight | Launch date | Length (m) | Diameter (m) | Mass (kg) |
|---|---|---|---|---|---|
| Z1 Truss | 3A - STS-92 | October 11,2000 | 4.9 | 4.2 | 8,755 |
| P6 Truss - Solar Array | 4A - STS-97 | November 30,2000 | 73.2 | 10.7 | 15,900 |
| S0 Truss | 8A - STS-110 | April 8,2002 | 13.4 | 4.6 | 13,970 |
| S1 Truss | 9A - STS-112 | October 7,2002 | 13.7 | 3.9 | 12,598 |
| P1 Truss | 11A - STS-113 | November 23,2002 | 13.7 | 3.9 | 12,598 |
| P3/4 Truss - Solar Array | 12A - STS-115 | September 29,2005 | 73.2 | 10.7 | 15,900 |
| P5 Truss | 12A.1 - STS-116 | December 1,2005 | 13.7 | 3.9 | 12,598 |
| S3/4 Truss - Solar Array | 13A - STS-117 | February 9,2006 | 73.2 | 10.7 | 15,900 |
| S5 Truss | 13A.1 - STS-118 | March 30,2006 | 13.7 | 3.9 | 12,598 |
| S6 Truss - Solar Array | 15A - STS-119 | July 13,2006 | 73.2 | 10.7 | 15,900 |
Diagram of ISS Truss elements
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