'Albert Einstein' Primed for Space Station Resupply Mission

Ten days after leaving Earth, the Automated Transfer Vehicle - boasting its unique X-shaped configuration of solar arrays - will dock with the Zvezda module of the International Space Station. Photo Credit: NASA

Ten days after leaving Earth, the Automated Transfer Vehicle, boasting its unique X-shaped configuration of solar arrays, will dock with the Zvezda module of the International Space Station. Photo Credit: NASA

Europe’s second-to-last Automated Transfer Vehicle (ATV-4), named in honor of German-born physicist Albert Einstein, will roar aloft from the Guiana Space Centre in Kourou, French Guiana, late Wednesday, en-route to the International Space Station. The proven craftwhose future prospects include a potential role in the Orion Service Module for NASA’s Beyond Earth Orbit aspirationswill fly atop the heavy-lift Ariane 5 booster from the ELA-3 complex, with liftoff due at 6:52:13 p.m. local time (10:52:13 p.m. UTC). This will be a mission of records. Weighing a mammoth 44,830 pounds, ATV-4 tips the scales as the heaviest vehicle ever lofted by an Ariane rocket and will transport 5,500 pounds of supplies to the station’s Expedition 36 crew, marking the largest payload of dry cargo ever ferried into orbit by a European spacecraft.

Measuring 34 feet long and 15 feet in diameter, the ATV consists of three main components: an Integrated Cargo Carrier (ICC), which houses its pressurized payloads, together with an Avionics Module for computers, gyroscopes, navigation and control systems, and electrical power and communications facilities, and a Propulsion Module to support rendezvous and docking, as well as periodic “re-boosts” of the ISS orbit. Power comes from four solar arrays, which form an X shape when fully deployed and have a total electrical yield of 3,800 watts. Unlike Japan’s H-II Transfer Vehicle (HTV), SpaceX’s Dragon, and Orbital Sciences Corp.’s Cygnus, the ATV is not designed to berth at the U.S. segment of the ISS, but at the Russian “end.” Consequently, it is equipped with a Russian-compatible Progress-type docking mechanism.

Since the launch of the first ATVnamed for Jules Verne, the 19th-century French science-fiction writer and visionaryback in March 2008, the craft has seen regular service at the space station. ATV-1 spent six months aloft and was undocked and intentionally burned up during re-entry the following September. Next came ATV-2, which paid homage to 17th-century German astronomer Johannes Kepler and which flew from February-June 2011. Most recently, in March of last year, ATV-3 was launched and bore the name of Italian physicist Edoardo Amaldi. This third craft was deorbited in October 2012. With “Albert Einstein” now picking up the baton, the ATV-4 mission is expected to run for about four months, with undocking planned in late October. Only one further voyage, ATV-5, named for Belgian astronomer Georges Lemaître, is scheduled to take place and will fly in the summer of 2014. Last April, the European Space Agency (ESA) announced that no further ATVs would be built, but earlier this year it was revealed that ATV technology will be utilized for the Orion Service Module.

Construction of ATV-4 has been undertaken in Turin, Italy, and Bremen, Germany, and the complete spacecraft was shipped from Bremen harbor on 31 August 2012, bound for Kourou, within the tiny French overseas region on the north Atlantic coast of South America. Three weeks later, it arrived in French Guiana to begin processing for a projected April 2013 liftoff. That target has moved substantially to the right, due to a combination of factors, including the need to replace a failed avionics box aboard the spacecraft.

The patch for ATV-4 - the fourth of five Automated Transfer Vehicles, bound for the ISS - highlights its dedication to German-born physicist Albert Einstein. Image Credit: ESA

The patch for ATV-4the fourth of five Automated Transfer Vehicles, bound for the ISShighlights its dedication to German-born physicist Albert Einstein. Image Credit: ESA

In the meantime, the booster itself arrived in French Guiana in February, primed for Flight VA-213, which will represent the 213th mission by the European launch organization’s Ariane family since the maiden voyage of its Ariane 1 rocket in December 1979. Flight VA-213 will also be the 69th launch of the Ariane 5, which first flew in June 1996. Last month, ATV-4 was installed by crane atop the rocket inside the 295-foot Final Assembly Building (BAF) at the Guiana Space Centre, and the payload was encapsulated within Ariane 5’s bullet-like fairing on 24 May. This relatively late encapsulation allowed for the loading of last-minute cargo items for the ISS delivery mission. “The station’s needs change with every mission, and there are always last-minute requests of every kind,” noted ESA in an ATV-4 pre-launch update. “A new Late Cargo Access Means lift will be used to load larger and heavier bags during the last weeks before launch. This allows for greater flexibility when ATV is already on top of its Ariane 5 rocket.”

Rollout of the VA-213 vehicle from the BAF is scheduled to occur today (Tuesday), ahead of tomorrow’s scheduled liftoff. Standing 171 feet tall and weighing 1.7 million pounds, the two-stage Ariane 5 represents one of the most powerful launch vehicles in operational service. Since its ill-fated first flight in June 1996, it has supported 68 missions, of which only four have been classified as total or partial failures. On its very first launch, it succumbed to a control software glitch, which caused Ariane to veer from its intended flight path and its flight termination system was activated to destroy the vehicle. The second mission, in October 1997, fared better, but suffered a premature shutdown of its core stage and failed to attain orbit. Two others, in July 2001 and December 2002, also underperformed, but Ariane 5 has maintained an unblemished record ever since. Its most recent flight, in February 2013, boosted the Amazonas-3 and Azerspace-1/Africasat-1A communications satellites into orbit.

In the final hours before tomorrow’s launch, the electrical systems aboard Ariane 5 will be checked and at T-4 hours and 50 minutes the lengthy process will begin to load 260,000 pounds of liquid oxygen and 50,000 pounds of liquid hydrogen into the 100-foot-tall “cryotechnic main stage.” These propellants will feed the stage’s single, French-built Vulcain-2 engine, which will produce 300,000 pounds of thrust. As the clock ticks closer to launch, Ariane’s propellant tanks will be pressurized for flight at T-4 minutes and the vehicle will be transferred to internal power. In the final seconds, the on-board systems will assume primary control of all critical functions and the guidance systems will be unlocked to flight mode. Ignition of the Vulcain engine will be followed, seven seconds later, by the ignition of twin, side-mounted solid-rocket boosters, each capable of a 1.4-million-pound propulsive yield. At this stage, VA-213 will be committed to flight.

An Ariane 5 heavy-lift booster carries the ATV-3 payload into orbit last year. Photo Credit: Space Safety Magazine

An Ariane 5 heavy-lift booster carries the ATV-3 payload into orbit last year. Photo Credit: Space Safety Magazine

The Ariane 5 will rise from the ELA-3 (Ensemble de Lancement Ariane) complex and promises to kick off the ATV-4 mission in spectacular fashion. Twelve seconds after T-zero, the rocket will begin a computer-commanded pitch and roll program maneuver, tilting its trajectory toward the northeast and establishing it on the proper flight azimuth for a 51.6-degree-inclined orbit and an altitude of about 150 miles. “It will maintain its attitude,” noted Arianespace in its VA-213 launch kit, “to keep the launcher’s axis parallel to its airspeed vector in order to minimize aerodynamic loads throughout the atmospheric phase of the launch, until the solid boosters are jettisoned.”

Following the departure of the boosters, at T+142 seconds, the Ariane will continue to climb, under the impulse of its Vulcain core engine. At three and a half minutes, ATV-4’s payload fairing will be released and the Vulcain will shut down, and the core stage will be discarded at about nine minutes into the flight. “On this mission, the main stage will fall back into the Atlantic Ocean, off the coast of Portugal,” continued Arianespace. The turn will then come for Ariane 5’s second stage, powered by a restartable Aestus engine, with a vacuum thrust of 6,100 pounds. This engine is fueled by unsymmetrical dimethyl hydrazine and nitrogen tetroxide and will burn for eight minutes, then shut down and enter a lengthy period of coasting, ahead of its second burn. “Following a ballistic phase, lasting 45 minutes, the upper stage is then reignited to circularize the orbit, directing the ATV, once separated into its targeted final orbit,” concluded the Arianespace launch-plan synopsis. The Aestus’ second burn will last about 30 seconds.

By now, an hour will have elapsed since launch, and at T+63 minutes ATV-4 will separate from the final stage of the Ariane 5. “Albert Einstein”or at least a spaceg-going namesake of the great physicistwill finally reach the environment about which he had written, studied, and theorized almost a century ago. Ten days of maneuvers will lie ahead of the cargo craft before its scheduled arrival and docking at the aft port of the International Space Station’s Zvezda module on 15 June, carefully watched by Expedition 36 Commander Pavel Vinogradov. It will remain a pressurized component of the expansive outpost until late October, whereupon it is due to be undocked and deorbited. According to NASA’s Expedition 35/36 press kit, the ATV-4 cargo includes drinking water, food, clothes, equipment, and propellant, and the spacecraft is expected to support periodic boosts of the space station’s orbit. A test of this capability is scheduled for later in June, ahead of a full-up re-boost on 10 July.

 

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