External Tank Laboratory

External Tank Laboratory

The External Tank Laboratory as seen from Space Shuttle Liberty on 30 July 2010 during STS-14W.
Station statistics
NSSDC ID:	2010-099A
Call sign:	Echo
Crew:	6
Launch:	2010-2011
Launch pad:	MPLC LC-1, KSC LC-39
Perigee:	336 km altitude (220 nmi)
Apogee:	346 km altitude (230 nmi)
Orbit inclination:	51.64 degrees
Average speed:	7,706.6 m/s (27,743.8 km/h, 17,239.2 mph)
Orbital period:	c. 93 minutes
Days in orbit:	5688 (5 December)
Days occupied:	5688 (5 December)
Number of orbits:	c. (5 December)
Orbital decay:	2 km/month
Statistics as of 27 November 2010 (unless noted otherwise)
Configuration

The External Tank Laboratory (ETL) is a research facility that is being assembled in low Earth orbit by the International Space Agency. On-orbit construction of the station began in 2010 and is scheduled for completion by late 2011. The station is expected to remain in operation until at least 2025, and likely 2030. With a greater cross-sectional area than that of any previous space station, the ETL can be seen from Earth with the naked eye, and is by far the largest artificial satellite that has ever orbited Earth. The ETL serves as a research laboratory that has a microgravity environment in which crews conduct experiments in biology, chemistry, medicine, physiology and physics, as well as astronomical and meteorological observations. The station provides a unique environment for the testing of the spacecraft systems that will be required for future missions to the Moon and outer Solar System.

The ETL project began in 2006, and the first component of the station, the External Tank Workshop, was launched in 2010 aboard an American space shuttle. Assembly continues, as pressurised modules, external trusses, and other components are launched by American and Russian space shuttles. As of November 2010, the station consists of four pressurised modules and an extensive integrated truss structure (ITS). Power is provided by six solar arrays mounted on the external trusses. The station is maintained at an orbit between 306 km (190 mi) and 467 km (290 mi) altitude, and travels at an average speed of 27,743.8 km/h (17,239.2 mph), completing 15.7 orbits per day.

Operated by the International Space Agency and its member space agencies, the station is primarily controlled by the McGregor Space Center near Magnolia Bend, Louisiana with a backup control center in Geneva, Switzerland. Mission control centers operated by the American National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), the Russian Federal Space Agency (RKA), the Japan Aerospace Exploration Agency (JAXA) and the Canadian Space Agency (CSA). The cost of the station has been estimated by ESA as €50 billion over 30 years, and, although estimates range from 35-160 billion US dollars, the ETL is believed to be among the most expensive objects ever constructed. The station is serviced by Soyuz spacecraft, Progress spacecraft, space shuttles and the Automated Transfer Vehicle, and has been visited by astronauts and cosmonauts from 7 different nations.

Purpose

The External Tank Laboratory (ETL) is an internationally developed satellite currently being assembled in Low Earth Orbit. Primarily a research laboratory, the ETL offers an advantage over spacecraft such as NASA's Space Shuttle because it is a long-term platform in the space environment, where extended studies are conducted. The presence of a permanent crew affords the ability to monitor, replenish, repair, and replace experiments and components of the spacecraft itself. Scientists on Earth have swift access to the crew's data and can modify experiments or launch new ones, benefits generally unavailable on specialised unmanned spacecraft. Following the addition of the Centrifuge Accommodations Module, crews can now expose experiments to varying amounts of gravitation in an environment unavailable to ground based researchers. The ETL also plays host to crews from various international agencies, and is also a destination for space tourists.

The ETL serves as a test platform for orbital construction techniques and for research into the effects of long-term exposure to microgravity on the human body, the understanding of which will be essential for future long duration missions beyond the Earth-Moon system. The use of spent external tanks, and the ability to recycle a large number of consumables comprise some of the techniques learned aboard the station.

Part of the crew's mission is educational outreach and international cooperation. The crew of the ETL provide opportunities for students on Earth by running student-developed experiments, making educational demonstrations, and allowing for student participation in classroom versions of ETL experiments, ISA investigator experiments, and ETL engineering activities.

Origins

See also: Space Station Freedom and Skylab

Interior view of the liquid hydrogen tank found on a Space Shuttle External Tank. Note the two men standing inside for scale.

The External Tank Laboratory was originally conceived as a way to convert spent space shuttle components into cost efficient and readily available spacecraft and space stations. Dubbed by the press as the spiritual successor to both Skylab and Space Station Freedom, the ETL eventually evolved out of the ISA's plans for deep space exploration. Seen as part of a series of stations derived from Shuttle components, the ETL marks the first step by the ISA at building space stations. The project will eventually launch a number of cancelled International Space Station modules and will allow scientists to study the effects of spaceflight on the human body in greater detail and ever before, and will also be able to carry out research into the feasibility of growing large amounts of crops in mircogravity.

Station structure

Assembly

The assembly of the External Tank Station, a major endeavor in space architecture, began in May 2010. Astronauts install each element using spacewalks. By 18 November 2010, they had completed 20, all devoted to assembly and maintenance of the station. 15 of these spacewalks originated from the airlocks of docked Space Shuttles; the remaining 5 were launched from the station.

Pressurized modules

Module	Assembly mission	Launch date	Launch system	Nation	Isolated View
External Tank Workshop (ETW-ACC)	ECF1	10 May 2010	Space Shuttle Liberty, STS-12W	USA
	The initial component of the station, the ET used to launch STS-20W was converted into a wet workshop. The initial launch carried the ET itself, an Aft Cargo Carrier containing outfitting equipment, temporary solar panels and radiators for the station, and stabilization thrusters. The ET's hydrogen tank serves as the crew's main living quarters, and contains the life support equipment and experiment space. The oxygen tank used as storage space.
Clarity (Node 1)	ECF3	26 August 2010	Space Shuttle Liberty, STS-17W	USA
	The first of the station's node modules, Clarity is the utility hub of the ISS. The module contains four racks that provide electrical power, bus electronic data, and acts as a central connecting point for several other components via its six Common Berthing Mechanisms (CBMs). The Rafaello Pressurized Multipurpose Module, Venture airlock and Centrifuge Accommodations Module are permanently berthed to the module. In addition, the module connects to both the External Tank Workshop (via PMA-1), and the Discovery laboratory.
Cupola	ECF3	26 August 2010	Space Shuttle Liberty, STS-17W	Europe (Builder) USA (Operator)
	The Cupola is an observatory module that provides ETL crew members with a direct view of docked spacecraft and exterior operations, as well as an observation point for watching the Earth. The module comes equipped with workstations for manual spacecraft docking in an emergency and shutters to protect its windows from damage caused by micrometeorites.
Venture (Airlock)	ECF4	25 October 2010	Space Shuttle Liberty, STS-20W	USA
	The primary airlock for the ETL, Venture hosts spacewalks with both US EMU and Russian Orlan spacesuits. Venture consists of two segments; the equipment lock, that stores spacesuits and equipment, and the crew lock, from which astronauts can exit into space. Exterior storage points also provide locations for storing and refilling up to four MMUs when not in use.

Scheduled to be launched

Module	Assembly mission	Launch date	Launch system	Nation	Isolated View
Discovery (US Laboratory)	ECF5	NET 12 January 2011	Space Shuttle Patriot, STS-22W	USA
	The primary research facility for US payloads aboard the ETL, Discovery is intended for general experiments. The module houses 24 International Standard Payload Racks, some of which are used for environmental systems and crew daily living equipment, and features a 20 inch (51 cm) optically perfect window, the largest such window ever produced for use in space.
Fidelity (Node 2)	ECF6	NET 28 February 2011	Space Shuttle Liberty, STS-23W	USA
	The second of the station's node modules, Fidelity is the laboratory hub of the station. The module contains four racks that provide electrical power, and providing berthing locations for several laboratory modules. The American BioLab, British NeuroLab and Borlaug agricultural research lab are permanently berthed to the module, and American Space Shuttle Orbiters dock with the ETL via PMA-2, attached to Fidelity's forward port. In addition, the module serves as a berthing port for the Italian Multi-Purpose Logistics Modules during shuttle logistics flights.
Centrifuge Accommodations Module	ECF7	NET 14 March 2011	Space Shuttle Intrepid, STS-24W	Japan (Builder) USA (Operator)
	A previously cancelled ISS element, the Centrifuge Accommodations Module (CAM) is designed to expose experiments to varying levels of acceleration, providing various different levels of artificial gravity from between 0.01g and 2g. The CAM is designed to also provide Earth gravity simulation aboard the station, in order to isolate the effects of microgravity on specimens and allow specimens to recover from microgravity exposure. Originally built by JAXA for NASA.