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ESA has Fruitfully Performed a Completely Computerized Docking for the First Time with ISS

ATV Jules Verne, the European Space Agency’s first resupply and reboost vehicle, has successfully performed a fully automated docking with the International Space Station (ISS). This docking marks the beginning of Jules Verne’s main servicing mission to deliver cargo, propellant, water, oxygen and propulsion capacity to the Station, as well as ESA’s entry into the restricted club of the partners able to access the orbital facility by their own means.

The 19-ton unmanned spaceship manoeuvred from a holding position 39 km behind the 275-ton space outpost and conducted a 4-hour staged approach with several stops at reference points for checks. It autonomously computed its own position through relative GPS (comparison between data collected by GPS receivers both on the ATV and the ISS) and in close range it used videometers pointed at laser retroreflectors on the ISS to determine its distance and orientation relative to its target. Final approach was at a relative velocity of 7 cm/s and with an accuracy of less than 10 cm, while both the ATV and the ISS were orbiting at about 28000 km/h, some 340 km above the Eastern Mediterranean. ATV Jules Verne’s docking probe was captured by the docking cone at the aft end of Russia’s Zvezda module at 16:45 CEST (14:45 GMT). Docking was completed with hooks closing at 16:52 CEST (14:52 GMT).

First automated docking
This is the very first time in Europe that an automated docking is performed in due respect of the very tight safety constraints imposed by manned spaceflight operations. All the approach and docking phase was piloted by the ATV’s onboard computers under close monitoring by the teams of ESA, CNES (the French Space agency) and Astrium (the prime contractor) at the ATV Control Centre at CNES Toulouse, France, as well as the ISS crew inside the Zvezda module. In case of anomaly, both ends could trigger pre-programmed manoeuvres to hold position, retreat to the previous reference point or escape to a safe distance.
The ATV’s behaviour was also under surveillance from its own independent Monitoring & Safing Unit (MSU), which uses a separate set of sensors and computers to check that the approach manoeuvre is conducted safely. In case of major anomaly, the MSU would have been able to take over the commands and order a Collision Avoidance Manoeuvre (CAM) through dedicated avionics chains and thrusters.

As all operations went smoothly, none of these safety manoeuvres was required during this afternoon’s approach and docking.

The ATV Jules Verne was launched by an Ariane 5 from Europe’s spaceport in Kourou, French Guiana, on 9 March. Three days later, it successfully demonstrated its autonomous CAM capability and was cleared for ISS proximity operations. The spaceship then moved to a parking orbit for the duration of space shuttle Endeavour’s visit to the ISS. On March 29 and 31 it conducted two rehearsals of today’s docking, approaching at 11 m from the Station.

New delivery service
Now that it is docked, the ATV Jules Verne will become an additional module of the ISS for about four months. The astronauts will enter its pressurized cargo module and retrieve 1,150 kg of dry cargo, including food, clothes and equipment as well as two original manuscripts handwritten by Jules Verne and a XIXth century illustrated edition of his novel “From the Earth to the Moon”. In addition, they will pump 856 kg of propellant, 270 kg of drinking water and 21 kg of oxygen into Zvezda’s tanks.

The ATV can carry about three times as much payload as Russia’s Progress freighters but on this mission, most of it is actually propellant to be used by the ATV’s own propulsion system for periodical manoeuvres to increase the altitude of the ISS in order to compensate its natural decay caused by atmospheric drag. If required, the ATV will also be able to provide redundant attitude control to the ISS or even perform evasive manoeuvres to move the Station out of the way of potentially dangerous space debris. The first of ATV Jules Verne’s reboost manoeuvres is currently scheduled on 21 April.

“The ATV is so much more than a simple delivery truck, it is an intelligent and versatile spaceship which has just demonstrated its extraordinary skills,” said Daniel Sacotte, ESA’s Director for Human Spaceflight, Microgravity and Exploration. “It is the largest and most complex spacecraft ever developed in Europe and the second in size of all the vehicle’s visiting the Station, after NASA’s space shuttle. With Columbus and the ATV, we have entered the major league of the ISS.”

“The docking of the ATV is a new and spectacular step in the demonstration of European capabilities on the international scene of space exploration ”said Jean-Jacques Dordain, ESA’s Director General. “This fantastic step is in first instance the result of collective work in Europe, including ESA Member States, industry under Astrium as prime contractor, CNES and ESA staff as well as among ISS partners, in particular the USA and Russia. We shall now reap the benefits of such investments after the launch of ESA’s Columbus laboratory, first in utilizing the unique capabilities of the ISS and secondly in preparing for the exploration of the Solar System. Now that the ATV is "up and running", I am happy to announce that in the next few weeks ESA will launch a recruitment campaign to hire new European astronauts"

About International Space Station
The International Space Station (ISS) is a research facility currently being assembled in space. The on-orbit assembly of ISS began in 1998. The space station is in a low Earth orbit and can be seen from Earth with the naked eye: it has an altitude of approximately 350 km (217 mi) above the surface of the Earth, and travels at an average speed of 27,700 km (17,210 statute miles) per hour, completing 15.77 orbits per day. The ISS is a joint project among the space agencies of the United States (NASA), Russia (RKA), Japan (JAXA), Canada (CSA) and eleven European countries (ESA).

The Brazilian Space Agency (AEB, Brazil) participates through a separate contract with NASA. The Italian Space Agency similarly has separate contracts for various activities not done in the framework of ESA's ISS works (where Italy also fully participates). China has reportedly expressed interest in the project, especially if it is able to work with the RKA. The Chinese are currently not involved, however.

The ISS is a continuation of what began as the U.S. Space Station Freedom, the funding for which was cut back severely. It represents a merger of Freedom with several other previously planned space stations: Russia's Mir 2, the European Columbus and Kibo, the Japanese Experiment Module. The projected completion date is 2010, with the station remaining in operation until around 2016. As of 2008, the ISS is already larger than any previous space station.

The ISS has been continuously inhabited since the first resident crew entered the station on November 2, 2000, thereby providing a permanent human presence in space. The crew of Expedition 16 are currently aboard. At present the station has a capacity for a crew of three. In order to fulfill an active research program it will be necessary to eventually hold 6 crew members. Early crew members all came from the Russian and U.S. space programs. German ESA astronaut Thomas Reiter joined the Expedition 13 crew in July 2006, becoming the first crew member from another space agency. The station has, however, been visited by astronauts from 15 countries. The ISS was also the destination of the first five space tourists.

The station is serviced primarily by Russian Soyuz and Progress spacecraft and by U.S. Space Shuttle orbiters. On March 9, 2008, the European Space Agency ESA launched an Ariane 5 with the first Jules Verne ATV Automated Transfer Vehicle toward the ISS carrying over 8,000 kilograms of cargo. Successful docking took place at 1440 GMT on 3 April 2008.

The assembly of the International Space Station is a major aerospace engineering endeavor. When assembly is complete the ISS will have a pressurized volume of approximately 1,000 cubic meters. Assembly began in November 1998 with the launch of Zarya -- the first ISS module -- on a Proton rocket, and as of March 2008 assembly is about 70% complete.

Two weeks after Zarya was launched, the STS-88 shuttle mission followed, bringing Unity, the first of three node modules, and connecting it to Zarya. This bare 2-module core of the ISS remained unmanned for the next one and a half years, until in July 2000 the Russian module Zvezda was added, allowing a maximum crew of three astronauts or cosmonauts to be on the ISS permanently.

About Ariane 5
Ariane 5 is a European expendable launch system designed to deliver payloads into geostationary transfer orbit or low Earth orbit.

It is manufactured under the authority of the European Space Agency (ESA) and the Centre National d'Etudes Spatiales (CNES), with EADS Astrium Space Transportation (Astrium) as prime contractor, leading a consortium of sub-contractors. The rocket is operated and marketed by Arianespace as part of the Ariane programme. Astrium builds the rockets in Europe and Arianespace launches them from the Guiana Space Centre.

It succeeded Ariane 4, but does not derive from it directly. Its development took 10 years and cost €7 billion. Ariane 5 has been refined since the first launch in successive versions, G, G+, GS, ECA, and most recently, ES. ESA originally designed Ariane 5 to launch the manned mini shuttle Hermes, and thus intended it to be "human rated" from the beginning. After ESA cancelled Hermes, the rocket became a purely robotic launcher.

Two satellites can be mounted using a Sylda carrier. Three main satellites are possible depending on size. Up to eight secondary payloads, usually small experiment packages or minisatellites, can be carried with an ASAP (Ariane Structure for Auxiliary Payloads) platform.

By mid 2007, Arianespace has ordered a total of 99 Ariane 5 launchers from Astrium. The first batch ordered in 1995 consisted of 14 launchers, while the second - P2 - batch ordered in 1999 consisted of 20 launchers . A third - PA - batch consisting of 25 ECA and 5 ES launchers was ordered in 2004. The latest batch ordered in mid 2007 consist of another 35 ECA launchers. Through these orders, the Ariane 5 will be the workhorse of Arianespace at least through 2015.

Ariane 5’s cryogenic H158 main stage (H173 for Ariane 5 ECA) is called the EPC "Étage Principal Cryotechnique" (Cryotechnic Main Stage). It consists of a large tank 30.5 metres high with two compartments, one for 130 tonnes of liquid oxygen and one for 25 tonnes of liquid hydrogen, and a Vulcain engine at the base with thrust of 115 tonnes-force (1.13 meganewtons). This part of the first stage weighs about 15 tonnes when empty.

Attached to the sides are two solid propellant boosters, P238 (P241 for Ariane 5 ECA), each weighing about 277 tonnes full. Each delivers a thrust of about 630 tonnes-force (6.2 MN). These boosters can be recovered with parachutes, like the Space Shuttle Solid Rocket Boosters. They may have been retrieved for examination on early missions, but are not reused.

The second stage is on top of the main stage and below the payload. The Ariane 5G used the EPS (Étage à Propergols Stockables/Storable Propellant Stage), which is fueled by monomethylhydrazine (MMH) and nitrogen tetroxide, whereas the Ariane 5 ECA uses the ESC (Étage Supérieur Cryotechnique/Cryogenic Upper Stage), which is fueled by liquid hydrogen and liquid oxygen. The payload and all upper stages are covered at launch by the fairing, which splits off once sufficient altitude has been reached. Ariane 5G+ used and Ariane 5 GS and ES use an improved EPS upper stage. The EPS upper stage is capable of re-ignition, which has been demonstrated twice. The first demonstration occurred during flight V26, which was launched on 5 October 2007. This was purely to test the engine, and occurred after the payloads had been deployed. The first operational use of restart capability as part of a mission, came on 9 March 2008, when two burns were made to deploy the first Automated Transfer Vehicle into a circular parking orbit.

In figure 1, Jules Verne ATV docking

In figure 2, ESA DG and dignitaries at ATV-CC

In figure 3, The International Space Station as seen from the departing Space Shuttle Endeavour on STS-123