A giant Ariane 5 booster stands ready at the Guiana Space Centre in Kourou, French Guiana, awaiting a nocturnal liftoff at precisely 8:47:38 p.m. local time (7:47:38 p.m. EDT) on Tuesday, 29 July, to deliver the European Space Agency’s (ESA) fifth and final Automated Transfer Vehicle (ATV-5) to provide equipment and supplies to the International Space Station (ISS). Originally scheduled to fly on 24 July, the mission was postponed by several days to permit what Arianespace—the Paris, France-based launch services organization—described as “complementary verifications on the Ariane 5 launch system.” That work has now been completed, and on Tuesday, 22 July, Arianespace announced the revised launch date. Assuming an on-time liftoff, ATV-5 will dock at the aft longitudinal port of the station’s Zvezda module on 12 August and is expected to remain until late January 2015.
Named in honor of the Belgian priest and astronomer Georges Lemaître (1894-1966), the spacecraft departed prime contractor Astrium’s facility in Bremen, Germany, last 7 October, bound for Kourou, on the north Atlantic coast of the tiny French overseas region of French Guiana. “Like its predecessors,” noted Astrium in a news release, “ATV-5 ‘Georges Lemaître’ is being transported by ship in three special containers. At the same time, around 80 sea containers full of test equipment are joining it on its journey.” Following its arrival at the South American spaceport, it underwent extensive tests from November onward—including evaluations of its electricity-generating solar arrays—and its first cargo was loaded earlier this year. According to Arianespace, ATV-5 will deliver about 5,730 pounds (2,600 kg) of dry cargo to the ISS, of which 60 percent was loaded by mid-April, with the remainder following over 30 June-1 July. “The dry cargo is contained in special bags that are positioned on racks inside the ATV’s Integrated Cargo Carrier,” it was reported, “with the locations calculated based on their contents and considerations for the resupply spacecraft’s center-of-mass determination.”
Measuring 34 feet (10.4 meters) long and 15 feet (4.6 meters) wide, ATV-5 includes the Integrated Cargo Carrier for pressurized payloads, together with a Service Module for its computers, gyroscopes, navigation and control subsystems, electrical power and communications hardware, and a propulsion module for rendezvous and periodic “reboosts” of the space station’s orbit. Weighing 44,224 pounds (20,060 kg), of which 43,929 pounds (19,926 kg) is ATV-5 itself, this will be the largest and heaviest payload ever launched by an Ariane 5. The ATV has the capacity to deliver up to 16,000 pounds (7,250 kg) of equipment and supplies into low-Earth orbit, including up to 12,100 pounds (5,500 kg) of dry cargo, up to 1,850 pounds (840 kg) of water, up to 220 pounds (100 kg) of pressurized gases, and up to 10,400 pounds (4,700 kg) of propellants. Whilst ATV-5 is incapable of returning items intact to Earth—and instead burns up in Earth’s atmosphere at the end of each mission—it can remain docked to the ISS for up to six months, far longer than other visiting vehicles, such as Japan’s H-II Transfer Vehicle (HTV), SpaceX’s Dragon, or Orbital Sciences’ Cygnus. Unlike those craft, the ATV is not designed to berth at the U.S. segment of the station, but rather to dock automatically at the Russian “end.” Consequently, it is outfitted with a Progress-type docking mechanism.
In late March, the hardware elements for the Ariane 5 vehicle assigned to the “VA-219” mission began to arrive in Kourou, aboard the MN Toucan ship. Then, in late April, the 100-foot-tall (30-meter) “cryotechnic main stage” was installed onto the operational launch table in the Launcher Integration Building (BIL). The next phase was the attachment of Ariane 5’s twin solid-fueled boosters, followed by the cryogenic upper stage and the Vehicle Equipment Bay (VEB), which contains its computerized “brain.” In the first week of June, Arianespace formally took delivery of the VA-219 vehicle, and on the 23rd it was rolled over from the BIL into the Final Assembly Building (BAF) for final processing operations and integration of the ATV-5 payload. By 5 July, the remaining time-critical payloads—including mango and orange juice, dental floss, bread pudding, cheese noodles, socks, T-shirts, and 110 pounds (50 kg) of coffee for the incumbent Expedition 40 crew—had been loaded in 57 “late cargo” bags and the spacecraft was secured atop the rocket. On 11 July, the bulbous payload fairing was installed around ATV-5.
Mission VA-219 will mark the 74th flight by an Ariane 5, which first flew in June 1996, and the 218th overall flight by a member of Arianespace’s rocket family since the maiden voyage of an Ariane 1, way back in December 1979. To date, Ariane 5 has proven an exceptionally reliable vehicle, having enjoyed 69 wholly successful missions. Only two have failed outright and two others have been classified as partial failures. On its first launch in June 1996, the Ariane 5 succumbed to a control software glitch, which caused it to veer from its intended flight path and the Flight Termination System (FTS) remotely destroyed the vehicle. The second flight, in October 1997, fared little better and suffered a premature shutdown of its core stage and failed to achieve orbit. Two others, in July 2001 and December 2002, also underperformed, but Ariane 5 has maintained an unblemished launch record ever since. The launch of ATV-5 will mark the third Ariane 5 mission of 2014, following hard on the heels of VA-217, which lofted the Athena-Fidus and ABS-2 satellites on 6 February and VA-216, which delivered the Astra 5B and Amazonas 4A satellites on 22 March. Another mission, VA-218, was scheduled to fly in early June, but has met with extensive delay, until at least September, due to the need for “additional verifications” of its Optus-10 satellite payload.
In accordance with standard procedures, a Launch Readiness Review for VA-219 occurred Saturday, 26 July, which concluded with authorization to proceed with Tuesday’s planned mission. The Ariane 5 stack was slated for rollout to the ELA-3 (Ensemble de Lancement Ariane) launch zone today (Monday), about 24 hours ahead of the opening launch attempt. Following rollout, Arianespace engineers will set to work establishing electrical, fluid, and other connections between the booster and the pad facilities.
Assuming that final preparations for Tuesday’s launch go smoothly, the loading of 260,000 pounds (118,000 kg) of liquid oxygen and 50,000 pounds (22,700 kg) of liquid hydrogen for the French-built Vulcain-2 engine of the first stage will get underway at T-4 hours and 50 minutes. The propellant tanks will be pressurized for flight at T-4 minutes, and the 171-foot-tall (52-meter) vehicle will transition to internal power supplies. In the final seconds, systems aboard the rocket will assume primary command of all critical functions and the guidance system will be unlocked to Flight Mode. The Vulcain-2 engine will roar to life at T-0, producing 300,000 pounds (136,000 kg) of thrust, although liftoff will not occur for another 7.5 seconds, as a series of computer-controlled health checks are undertaken. When all is verified to be well, the twin side-mounted solid-fueled boosters—each punching out about 1.4 million pounds (635,000 kg) of propulsive yield and together generating 92 percent of the thrust to get Ariane 5 off the pad—will ignite and VA-219 will be committed to its mission.
The stack will rise vertically for about five seconds, after which the two computers inside the VEB will initiate a combined pitch and roll program maneuver, actively rotating the vehicle onto a north-easterly trajectory and placing it onto the correct flight azimuth to insert ATV-5 into a 51.63-degree-inclined orbit. One minute into the ascent, the vehicle will go supersonic and pass “Max Q,” the period of maximum aerodynamic stress on the airframe. The twin boosters will be jettisoned at T+142 seconds, parachuting into the Atlantic Ocean about 300 miles (480 km) east of Kourou. Meanwhile, Ariane 5 will by now have reached a velocity of over 1,200 mph (1,900 km/h) and will continue to climb under the impulse of its Vulcain-2 engine.
Three and a half minutes into the flight, the bullet-like payload shroud will be detached, exposing ATV-5 to the space environment for the first time. Shutdown of the Vulcain-2 is expected about eight minutes and 53 seconds after launch, and the cryotechnic main stage will descend to a splashdown off the coast of Portugal. Meanwhile, the second stage—powered by a restartable, 6,100-pound-thrust (2,770-kg) Aestus engine—will ignite to pick up the baton for the final push into orbit. By now, the rocket will be over 105 miles (170 km) high and traveling at more than 4,300 mph (6,900 km/h). Fueled with unsymmetrical dimethyl hydrazine and nitrogen tetroxide, the Aestus will burn for about eight minutes, then shut down, for an extended period of coasting, ahead of a second, 30-second burn to circularize ATV-5’s orbit at about 150 miles (240 km). The second stage and ATV-5 will part company at T+63 minutes after liftoff.
With this event, Georges Lemaître—or, at least, his mechanized namesake—will enter independent flight at an altitude of 160 miles (260 km) and begin a complex series of orbit-raising and “phasing” maneuvers to gradually close the distance to the ISS, in readiness for an automatic docking at the aft longitudinal port of the Zvezda module on 12 August. At T+98 minutes into the mission, its “windmill” of four solar arrays will be deployed, bringing a total of 3.8 kilowatts of electrical power to the spacecraft. It will spend more than five months at the ISS, during which time it will be unloaded and will perform periodic “reboosts” of the station’s orbital altitude.
Following its scheduled departure on 25 January 2015, it will give a unique perspective, from the inside, of a vehicle’s destructive dive into the atmosphere. The ATV Break-Up Camera (BUC) and a spherical Re-entry SatCom capsule were developed in just nine months and will provide for the transmission of infrared images during the fiery destruction of the main body of the spacecraft. The experiment is described as giving “as full a picture as possible of the conditions inside the vehicle as it breaks up.” Bolted to a rack within the ATV, the camera itself will eventually burn up, but imagery of its final 20 seconds will be passed to the SatCom, which is protected by a ceramic heat shield. Break-up of ATV-5 is anticipated at an altitude of around 43-50 miles (70-80 km), after which the SatCom will descend at a velocity of about 15,660 mph (25,200 km/h). “The fall will generate high-temperature plasma around it, but signals from its omni-directional antenna should be able to make it through any gap in the plasma to the rear,” said Neil Murray, who leads the ESA project. Additionally, signals will continue after the SatCom has decelerated to an altitude of about 25 miles (40 km) levels, where a plasma “sheath” is no longer formed, by which time it will become visible to Iridium satellite relays.
ATV-5 will be the fifth and final mission by the ESA-provided cargo ship, which first flew in March 2008. The ATV-1 spacecraft was named for Jules Verne, the 19th-century French science fiction writer and visionary, and spent six months at the ISS, before it was undocked and returned to a destructive re-entry the following September. Next came ATV-2, which paid homage to the 17th-century German astronomer Johannes Kepler, and which flew from February-June 2011. This was followed by ATV-3, which honored Italian physicist Edoardo Amaldi and flew from March-October 2012. Most recently, ATV-4 was launched in June 2013, named for the great physicist Albert Einstein, which remained in orbit until November.
The selection by ESA of Lemaître’s name for ATV-5 came in February 2012 and was described as continuing “the tradition of drawing on great European visionaries to reflect Europe’s deep roots in science, technology and culture.” Georges Henri Joseph Édouard Lemaître, born in Charleroi, Belgium, on 17 July 1894, is today famous for having first proposed the theory of the expansion of the Universe and for deriving what we now known as “Hubble’s Law.” Lemaître’s research was published in 1927, two years ahead of the work of U.S. astronomer Edwin P. Hubble.
After a classical education at a Jesuit school, Lemaître entered the Université Catholique de Louvain to study civil engineering, but his work was stalled by the Great War. After serving Belgium as an army artillery officer, he returned to his studies, focusing on physics and mathematics and preparing for the priesthood. Upon receipt of his doctorate in 1920 and ordination as a priest in 1923, Lemaître entered the University of Cambridge, England, as a graduate student in astronomy, and later worked at Harvard College Observatory in Cambridge, Mass. Returning to Belgium in 1925, he became a part-time lecturer at the Université Catholique de Louvain and it was whilst there that he began work on the report which would earn him worldwide renown. In 1927, in the Annals of the Scientific Society of Brussels, Lemaître wrote of “A homogeneous Universe of constant mass and growing radius, accounting for the radial velocity of extragalactic nebulae.” Little read outside of his native Belgium, it was not until 1931 that the work was translated into English.
The famed theoretical physicist Albert Einstein is said to have regarded Lemaître’s ideas of an expanding universe with a measure of scorn, at first, to which the Belgian responded: “Your calculations are correct, but your physics is atrocious!” Invited to speak at a meeting of the British Association in London, Lemaître explained his conviction that the universe expanded from an initial point—which he labeled “The Primeval Atom”—and his work was subsequently published in the journal Nature. He referred to it as a “Cosmic Egg exploding at the moment of creation,” but in years to come it would become the cornerstone of what is today dubbed “The Big Bang.”
In recognition of his work, Lemaître received the Francqui Prize—Belgium’s highest scientific award—from King Léopold III. It was an award for which he had been nominated by Einstein and also by his mentor, the English astrophysicist Arthur Eddington. In 1936, he was elected a member of the Pontifical Academy of Sciences, of which he subsequently became president. Opposed to the mixture of science and religion, Lemaître disagreed with Pope Pius XII’s proclamation that his work validated the notion of Creationism. Both Lemaître and the pope’s scientific advisor, Daniel O’Connell, successfully persuaded Pius XII not to publicly mention Creationism again in a public setting. As head of the Pontifical Academy of Sciences, he continued his teaching workload, albeit in a reduced capacity, until shortly before his death. Lemaître died in Leuven, Belgium, on 20 June 1966, aged 71.
Early in 2012, ESA announced that it intended to shut down its ATV production line after the ATV-5 Georges Lemaître mission. It was specifically indicated that “a significant obsolescence problem” existed at equipment and component levels, limiting the desire or ability to reopen the line. Costing about $600 million, per unit, to build, the ATV operated as part of a “barter” arrangement between ESA and its ISS partners, covering its operating costs at the space station until 2017. A further $600 million investment was needed to cover the 2017-2020 timeframe, and Germany apparently favored participation in the design of the Service Module for NASA’s Orion spacecraft. In November 2012, it was reported that ESA was prepared to provide an ATV-based Service Module as “payment in kind” for continued involvement with the ISS through the end of the decade and, in early 2013, it was formally announced that Europe would indeed build the Service Module for Orion’s first Exploration Mission (EM-1), currently scheduled to launch atop the first Space Launch System (SLS) heavy-lift booster in December 2017.
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