Integrated Truss Structure
List of ISS modules
The Integrated Truss Structure (ITS; German: Integrated lattice structure ) is the supporting grid structure of the International Space Station ( ISS). It forms the backbone and is aligned perpendicular to the flight direction.
The ITS is the entire space station built as modular. The individual elements bear names of a and letters (. . " P" stands for port from engl port; "S " stands for Starboard, of Engl starboard ): P1, P3 / 4, P5 and P6 are in flight to the left arranged while the elements S1, S3 / 4, S5 and S6 are mounted on the right side. The S0 element is located in the center and is connected to the Destiny laboratory with the occupied portion of the station.
The Integrated Truss Structure is a cross-sectionally trapezoidal shaped rigid light metal structure with additional cross braces. For the connection of the individual segments of the grid structure there is a special "Module -to- truss segment attachment system." For each connection there is a remote controlled fishing bar that initially loosely connects the two elements and is tightened afterwards. In addition, then grab four motorized bolts which are additionally secured.
The grating structures were produced by Boeing, the radiators and solar panels manufactured Lockheed Martin for NASA.
- 2.1 solar panels
- 2.2 accumulators
- 2.3 Solar Alpha Rotary Joint
- 2.4 Crew and Equipment Translation Aid ( CETA )
Lattice structure
Integrated Truss Structure Z1
The Z1- Gitterlement ("Z" stands for Zenit ) was brought in October 2000 by the STS -92 mission to the space station and mounted on the top of the module Unity. In Z1 four gyroscopes for attitude control of the station along with motors and heaters are installed. The gyros each have a mass of 315 kg and reach a maximum speed of 6,600 revolutions per minute ( angular momentum: 2.300 J ). Its dimensions are 4.9 m × 4.2 m with a total mass of 8.8 t. At Z1 two communication antennas for data and video images are mounted. Z1 was used in the construction phase of the station as a carrier of the P6 lattice tower with its solar panels. Therefore, power converters are also part of the equipment. Inside the module there is a small storage space, which is used for storage of equipment and spare parts. This is accessible from the Unity zenith by a lockable hatch.
Integrated Truss Structure S0
Starboard Zero S0 (English for starboard zero ) is the central segment of the 100 m long lattice structure of the International Space Station, which was installed in April 2002 by the STS -110 mission. S0 is connected by telescoping support legs with the laboratory module Destiny.
The S0 - grid element is 13.47 m long, 4.57 m wide, has a mass of 12,118 kg and consists of five separate bays. It also has a system for automatic connection to utility lines ( power, data, cooling ), a 6.40 m long radiator to radiate excess heat ( mainly from the energy systems ), a portable work platform, four GPS antennas for determining the position of the station, one of them independent system of two measuring complexes with three ring laser gyros, determine the accelerations in all three axes and calculate over computer the position of the station, a detector for charged particles, four power transfer switches, two circuit breakers, three halogen spotlights, two independent control systems for remote control for main functions, a variety of power cables with automatic connection devices and the Mobile Transporter ( MT).
The MT is an aluminum construction, 2.74 m long, 2.62 m wide and 97 cm high. He has a mass of 885 kg and runs on rails along the lattice structure. A complex software assumes control of the engine 20 for driving, detecting and connecting the power couplings. In the future, the mobile vans are ten docking sites on each grid segments available. Intermediate rail transporters and prevails in the locked state, a contact force of about 30 kN. The maximum payload is 20.9 tons.
Z1- grid element at the start of preparations
ISS lattice structure S0 during transport from the cargo bay of the Space Shuttle
Astronauts of the STS -113 mission to work on the P1- grid segment
ISS on October 9, 2000, after the installation of the P6 power module
The ISS with the first three parts of the grid structure: S1 - S0 - P1
The ISS after installing the P3/P4-Truss (right)
Integrated Truss Structure P1 and S1
Port Side One P1 was on 24 November 2002 aboard the Endeavour (STS- 113) and Starboard One S1 was brought into orbit on 7 October 2002 aboard the Atlantis ( STS -112 ) and both was three days later at the central module S0 coupled. The two elements are each about 14 meters long, 4.57 meters wide and have a mass of 12.5 tons. They each have a system for automatic connection of supply cables ( power, data, cooling ), a coolant tank, this includes a nitrogen tank, three radiators, each with 22 m length to radiate excess heat ( mainly from the energy systems ) together with the associated twist mechanism and control electronics, power converter and splitter, two video port stations, two passive and one active segment connecting systems and one each trolley ( CETA 1 and 2). Differences exist in the installed communication system S1 has an S- band antenna, a UHF communications system P1.
Integrated Truss Structure P2 and S2
The elements P2 and S2 were originally intended as drive elements, but were obsolete by the Russian participation in the station.
Integrated Truss Structure P3/P4 and S3/S4
Both elements consist of two individual segments, which were connected before the start: the grating structures P3 and S3, and the solar array P4 and S4, respectively. They differ slightly from each other: P3/P4 is 13.81 meters long, 4.88 meters wide and has a height of 4.75 meters and has a mass of 15.8 tons. S3/S4 is 13.66 meters long, 4.96 meters wide and 4.63 meters high with a weight of 16.2 tons.
The P3 ( S3) - element is the SARJ joint ( Solar Alpha Rotary Joint) pivotally connected to the P4 (S4 ) element to which there are two fold out solar panels that are used for energy production. The blades are rotatably mounted and can be oriented perpendicular to the sun. Within the lattice structure of the P4 ( S4) - element are batteries to store the energy generated. Also located on the element and a radiator which emits excess heat into space and thus cool the electronics of the solar collector.
The P3/P4-Element was taken in September 2006 with the Space Shuttle mission STS -115 into orbit and assembled at the P1 carrier.
S3/S4 was launched with the mission STS -117 in June 2007 to the ISS and installed on the S1 segment.
Integrated Truss Structure P5 and S5
In the segments of P5 and S5 are each a 3.37 m -long adapter piece to mount the P6 and S6 solar modules to the P4 and S4 solar modules can.
The P5- structure with the mission STS -116 (ISS 12A.1 ) in December 2006 and the S5 - structure in August 2007 with the mission STS -118 (ISS 13A.1 ) transported to the ISS.
Integrated Truss Structure P6 and S6
P6 and S6 are the outermost segments of the Integrated Truss Structure. Both consist of both a lattice structure as well as from solar panels.
P6 was taken during the STS -97 mission into space and initially attached to the December 3, 2000 at the base of Z1. It was relocated part of the ISS, the P5 element during the STS -120 mission on 30 October 2007 to its final location on the port side ( left side in direction of flight ).
With the S6 element is the last element of the Integrated Truss Structure with the mission STS -119 was launched into space. On 19 March 2009 it was attached to the S5 element. Thus, the construction of the Integrated Truss Structure was completed.
Modules
Solar panels
In addition to the smaller solar cells to the Russian modules which were used primarily to construction, the ISS has four large solar panels.
There are two each solar array at the ends of the ITS lattice structure: the elements of P6 and P4 on the larboard and S6 and S4 on the starboard side. The elements can be rotated 360 ° in order to be always perfectly aligned with the sun.
Each of the eight solar panels deployed 35,05 m long and 11.58 m wide. A surface whose mass is 1.1 t, consists of 32,800 individual solar cells, which are combined into strips of 400 pieces. A panel is made of 82 stripes and can generate 32.8 kW DC. Since both surfaces are deployed opposite each other, together they have a wingspan of 73 m.
Each solar panel ( Solar Array Wing ) consists of a collapsible lattice mast, two foldable solar panels, tension wires for extending or retracting the panels and devices for their control. In addition, facilities for stabilization and storage of electrical energy for cooling and all facilities are available. The electrical current passes through lines 82 per panel to three charging systems with two nickel-hydrogen batteries. The voltage is regulated to about 140 volts.
In theory, 31 kW harness. It can be provided for power, control the cooling equipment and the station at the same time. In addition, the batteries are charged ( up to 3 × 8.4 kW per solar cell area ).
The cooling system consists of the heat sinks with fins, which are in direct contact with the heat-generating parts, a plurality of cooling circuits with ammonia as a refrigerant, electrical pump, and a radiator which has theoretically 14 kW radiation power. All plants have a combined power requirement of more than 6 kW, which therefore is not eligible for use in the space station.
In summary, it is more of a small power plant, as a solar energy system to generate electricity. The complex systems are controlled by multiple computers, maintained during the operation of the space station and replaced if necessary. But the power module S6 cost about 1.2 billion U.S. dollars.
Accumulators
The nickel -hydrogen batteries provide the power for the station is available while it is in the shadow of the Earth. They are installed in the elements S4, P4, P6 and S6. Each battery consists of 38 individual cells, has 38,000 charge-discharge cycles, an estimated life span of six and a half years and a mass of 187 kg.
Solar Alpha Rotary Joint
The Solar Alpha Rotary Joint ( SARJ ) is a rotary joint, which has the task of the solar panels always nachzuführen just the sun in order to ensure the best possible energy. To the solar panels to be rotated so that the sun falls perpendicularly on the solar cells. The individual solar panels can additionally on their fortifications about a second axis - called Beta Gimbal Assembly ( BGA) - be rotated.
There are two SARJs of which connects the first segments and the second P3 and P4, the segments S3 and S4. The two joints are in the form of a wagon wheel and turn the respective ends of the grating structure consisting of the elements S4, S5 and S6, and P4, P5 and P6. All the electrical connections are made through slip-rings so that the joint does not need to be turned back.
With a diameter of 3.20 meters, a length of 1.02 meters and a mass of 1.1 tons, the SARJ can be rotated with an accuracy of one degree over 360 degrees. Was built the SARJ of Lockheed Martin.
On the starboard SARJ a very high wear was found in the course of 2008, the issue was resolved during the STS -126 mission.
Crew and Equipment Translation Aid ( CETA )
On the Integrated Truss Structure There are two additional CETA platforms. The Crew and Equipment Translation Aid ( CETA abbreviated, English for personnel and equipment transport assistance) is a mobile hand- barrow -like small platform which can be moved on the rails of the grid structure. It consists of an aluminum plate with attached mounts for payloads with guide wheels, locking devices, shock absorbers and different containers. She has a mass of 283 kg, 2.50 m long, 2.36 m wide and 0.89 m high. With folded arms CETA can be moved from one side of the mobile transporter to the other. Both systems use the same rail system.
During the Mobile Transporter, however, is thought t mass for the transport of loads up to about 20, CETA serves as an easy -to-use transport system for astronauts and small payloads.