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ATV-2 Johannes Kepler
Image Credit: European Space Agency (ESA)
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Keeping the International Space Station supplied will become an increasing challenge with the retirement of the US Space Shuttle in 2011.
The Japanese were schedule to launch their second H-II Transfer Vehicle (HTV-2) resupply mission today, 20 January, but weather has caused the mission to be rescheduled for a possible launch on Saturday.
The Russians fly their Progress spacecraft on resupply missions, and the next one is scheduled for 28 January.
Finally, the European Space Agency (ESA) has flown their Automated Transfer Vehicle once before (ATV-1 or Jules Verne) on 9 March 2008 and their next launch is coming up on 15 February 2011.
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The 20 ton Johannes Kepler ATV has a cargo capacity of up to 7 metric tons. The composition of this load can vary depending on the mission:
- 1.5 to 5.5 metric tons of freight and supplies (food, research instruments, tools, etc.)
- up to 840 kilograms of drinking water
- up to 100 kilograms of gases (air, oxygen and nitrogen)
- up to four metric tons of fuel for orbit correction and up to 860 kilograms of propellant to refuel the space station.
The spacecraft is compose of two main sections. The first is the ATV Service Module (below, left), which is not pressurized, includes propulsion systems, electrical power, computers, communications and most of the avionics. The ATV uses four main engines and 28 small thrusters to control the navigation of the spacecraft. Four solar panels are deployed after launch and supply 4800 Watts of power to the batteries and the electrical systems.
The second component is the Integrated Cargo Carrier (below, right). The large section in the front is pressurized and comprises about 90% of the cargo volume. It handles all the dry cargo, including the racks on each side. The inhabitants of the International Space Station access this area through the hatch in the Russian docking system.
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The Equipped External Bay of the Integrated Cargo Carrier (ICC) holds 22 spherical tanks of different sizes and colors. These tanks are used to re-supply the Station with propellant for the International Space Station propulsion system, various gases (air, oxygen, and nitrogen) and water for the crew.
The contents of these tanks are delivered to the Station through dedicated connections, or through manually operated hoses.
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ATV Liquid Resupply Tanks
Image Credit: ESA
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Russian Docking Module
Image Credit: ESA
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The ATV uses the Russian-made docking equipment sensors to perform the approach and docking sequence. The procedure is the same as with the Soyuz manned capsules and the Progress resupply spacecraft.
The Russian docking system enables physical, electrical and propellant connections with the Station. Access to the ICC is through the Russian hatch.
Once the ATV is securely docked, the crew can enter the cargo section and remove the payload, which usually includes maintenance supplies, science hardware, parcels of fresh food, mail and family tapes or DVDs.
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