The Extended Duration Orbiter (EDO) program was a project by NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 to prepare for long-term (months) microgravity research aboard Space Station Freedom

Space Station Freedom

Space Station Freedom was a NASA project to construct a permanently manned Earth-orbiting space station in the 1980s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, Freedom was never constructed or completed as originally designed, and after...

, which later evolved into the International Space Station

International Space Station

The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...

. Scientists and NASA needed practical experience in managing progressively longer times for their experiments. The original space shuttle

Space Shuttle

The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 configuration usually provided a week to ten days of spaceflight

Spaceflight

Spaceflight is the act of travelling into or through outer space. Spaceflight can occur with spacecraft which may, or may not, have humans on board. Examples of human spaceflight include the Russian Soyuz program, the U.S. Space shuttle program, as well as the ongoing International Space Station...

. Several research projects and hardware components were part of the project, of which the EDO-pallet was one of the most visible, contracted by Rockwell International

Rockwell International

Rockwell International was a major American manufacturing conglomerate in the latter half of the 20th century, involved in aircraft, the space industry, both defense-oriented and commercial electronics, automotive and truck components, printing presses, valves and meters, and industrial automation....

.

The first orbiter outfitted with the EDO hardware configuration was Endeavour

Space Shuttle Endeavour

Space Shuttle Endeavour is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States. Endeavour was the fifth and final spaceworthy NASA space shuttle to be built, constructed as a replacement for Challenger...

, during its construction, and its last EDO flight was STS-67

STS-67

STS-67 was a human spaceflight mission using that launched from Kennedy Space Center, Florida on 2 March 1995.-Crew:-Mission parameters:*Mass: payload*Perigee: *Apogee: *Inclination: 28.5°*Period: 91.5 min...

, in 1995. Endeavour's EDO modifications were removed in 1996 as part of routine maintenance, to reduce the orbiter's weight prior to STS-89

STS-89

STS-89 was a space shuttle mission to the Mir space station flown by Space Shuttle Endeavour, and launched from Kennedy Space Center, Florida on 22 January 1998.-Crew:-Crew notes:...

. Space Shuttle Columbia

Space Shuttle Columbia

Space Shuttle Columbia was the first spaceworthy Space Shuttle in NASA's orbital fleet. First launched on the STS-1 mission, the first of the Space Shuttle program, it completed 27 missions before being destroyed during re-entry on February 1, 2003 near the end of its 28th, STS-107. All seven crew...

 was outfitted for EDO flight during its maintenance period from August 10, 1991, through February 9, 1992, prior to STS-50

STS-50

-Backup crew:-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee: *Inclination: 28.5°*Period: 90.6 min- Mission highlights:...

, which was the first EDO flight. From 1992, through 1994, Atlantis

Space Shuttle Atlantis

The Space Shuttle Atlantis is a retired Space Shuttle orbiter in the Space Shuttle fleet belonging to the National Aeronautics and Space Administration , the spaceflight and space exploration agency of the United States...

 went through a maintenance period, during which Atlantis was modified to have the provisions needed for EDO capability, but NASA chose not to proceed with the final modifications, and Atlantis does not have EDO capability. The EDO-pallet used in these orbiter configurations was destroyed in the Columbia accident

Space Shuttle Columbia disaster

The Space Shuttle Columbia disaster occurred on February 1, 2003, when shortly before it was scheduled to conclude its 28th mission, STS-107, the Space Shuttle Columbia disintegrated over Texas and Louisiana during re-entry into the Earth's atmosphere, resulting in the death of all seven crew members...

.

EDO pallet

The Extended Duration Orbiter Cryogenic kit (EDO-pallet or CRYO) is a 15 feet (4.6 m) assembly of equipment which attached vertically to the payload bay rear bulkhead of an orbiter

Space Shuttle Orbiter

The Space Shuttle orbiter was the orbital spacecraft of the Space Shuttle program operated by NASA, the space agency of the United States. The orbiter was a reusable winged "space-plane", a mixture of rockets, spacecraft, and aircraft...

, and allowed the orbiter to support a flight of up to 16 days duration. The equipment includes cryogenic tanks, associated control panels, and avionics equipment. Although Atlantis was partially upgraded to accommodate the EDO, only Columbia and Endeavour actually flew with the pallet. The pallet made its debut on STS-50

STS-50

-Backup crew:-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee: *Inclination: 28.5°*Period: 90.6 min- Mission highlights:...

, and was lost on mission STS-107

STS-107

-Mission parameters:*Mass:**Orbiter Liftoff: **Orbiter Landing: **Payload: *Perigee: *Apogee: *Inclination: 39.0°*Period: 90.1 min- Insignia :...

, the Space Shuttle Columbia disaster.

Initially, NASA considered adding a second EDO pallet to Endeavour, placed in front of the first, for a total of thirteen tank sets, that would have allowed an orbiter to remain in space for 28 days, but managers decided against it when the International Space Station assembly began, and instead removed the EDO capability from the orbiter, to reduce its weight and allow it to carry more cargo to the ISS.

No replacement for the pallet is planned, since the Station-to-Shuttle Power Transfer System now provides much of the same abilities, and the planned 2011 retirement of the shuttle fleet would make it redundant.

Specifications

The EDO tanks stored 368 pounds (167 kg) of liquid hydrogen

Liquid hydrogen

Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...

 at -418 degrees Fahrenheit (-250 °C), and 3,124 pounds (1,417 kg) of liquid oxygen

Liquid oxygen

Liquid oxygen — abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries — is one of the physical forms of elemental oxygen.-Physical properties:...

 at -285 degrees Fahrenheit (-176 °C). Total empty weight of the system was 3,571 pounds (1,620 kg). When filled with cryogens, the system weight was approximately 7,000 pounds (3.2 t).

Use

Oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 and hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 were supplied to the orbiter's three electrical power generating fuel cell

Fuel cell

A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used...

s, where they were converted into sufficient electrical energy to support the average 4 family-member house for approximately 6 months. About 3,000 pounds of pure drinking water was also produced by the fuel cells.

Missions with the EDO pallet conducted research on microgravity

Weightlessness

Weightlessness is the condition that exists for an object or person when they experience little or no acceleration except the acceleration that defines their inertial trajectory, or the trajectory of pure free-fall...

, Life Science

Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

s, Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 and celestial observations

Astronomy

Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

, and human adaptation to the low gravity environment.

The following missions used the EDO pallet:

EDO Flight	Shuttle	Mission	Launch Date	Duration	Primary Payload(s)
1	Columbia	STS-50 STS-50 -Backup crew:-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee: *Inclination: 28.5°*Period: 90.6 min- Mission highlights:...	June 25, 1992	13 days, 19 hours, 30 minutes, 4 seconds	United States Microgravity Laboratory-1
2	Columbia	STS-58 STS-58 STS-58 shuttle mission of Space Shuttle Columbia launched from Kennedy Space Center, Florida, on 18 October 1993. It was also the last time Columbia would land at Edwards Air Force Base.-Crew:-Mission parameters:*Mass:...	October 18, 1993	14 days, 0 hours, 12 minutes, 32 seconds	Spacelab Life Sciences-2
3	Columbia	STS-62 STS-62 STS-62 was a Space Shuttle program mission flown aboard . The primary payloads were the USMP-02 microgravity experiments package and the OAST-2 engineering and technology payload, both in the orbiter's cargo bay. The two-week mission also featured a number of biomedical experiments focusing on the...	March 4, 1994	13 days, 23 hours, 16 minutes, 41 seconds	United States Microgravity Payload-2
4	Columbia	STS-65 STS-65 STS-65 is a Space Shuttle program mission of Columbia launched from Kennedy Space Center, Florida, 8 July 1994. The flight was commanded by Robert D...	July 8, 1994	14 days, 17 hours, 55 minutes, 1 second	International Microgravity Laboratory-2
5	Endeavour	STS-67 STS-67 STS-67 was a human spaceflight mission using that launched from Kennedy Space Center, Florida on 2 March 1995.-Crew:-Mission parameters:*Mass: payload*Perigee: *Apogee: *Inclination: 28.5°*Period: 91.5 min...	March 2, 1995	16 days, 15 hours, 8 minutes, 48 seconds	ASTRO-2
6	Columbia	STS-73 STS-73 STS-73 was a Space Shuttle program mission, during October–November 1995. The mission was the second mission for the United States Microgravity Laboratory. The crew, who spent 16 days in space, were broken up into 2 teams, the red team and the blue team...	October 20, 1995	15 days, 21 hours, 53 minutes, 16 seconds	United States Microgravity Laboratory-2
7	Columbia	STS-75 STS-75 STS-75 was a United States Space Shuttle mission, the 19th mission of the Columbia orbiter.-Crew:-Mission parameters:*Mass: payload*Perigee: *Apogee: *Inclination: 28.5°*Period: 90.5 min-Mission objective:...	February 22, 1996	15 days, 17 hours, 40 minutes, 22 seconds	Tethered Satellite System-1R (reflight of Tethered Satellite System-1 on STS-46 STS-46 STS-46 was a NASA space shuttle mission using orbiter Atlantis and launched on 31 July 1992 at 9:56:48 am EDT.-Crew:-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee:... ) United States Microgravity Payload-3
8	Columbia	STS-78 STS-78 STS-78 was the fifth dedicated Life and Microgravity Spacelab mission for the Space Shuttle program, flown partly in preparation for the International Space Station project...	June 20, 1996	16 days, 21 hours, 48 minutes, 30 seconds	Life and Microgravity Spacelab
9	Columbia	STS-80 STS-80 -Mission parameters:* Mass: payload* Perigee: * Apogee: * Inclination: 28.5°* Period: 91.5 min-Mission highlights:* The mission deployed two satellites and successfully recovered them after they had performed their tasks....	November 19, 1996	17 days, 15 hours, 53 minutes, 18 seconds	Wake Shield Facility Wake Shield Facility ]Wake Shield Facility is an experimental science platform that was placed in low-earth orbit by the Space Shuttle. It is a 3.7 meter diameter, free-flying stainless steel disk.... ORFEUS-SPAS II
10	Columbia	STS-83 STS-83 STS-83 was a mission of the United States Space Shuttle Columbia.-Crew:-Mission parameters:*Mass:**Orbiter Landing with payload: **MSL-1 Spacelab Module: *Perigee: *Apogee: *Inclination: 28.5°...	April 4, 1997	3 days, 23 hours, 13 minutes, 38 seconds	Microgravity Science Laboratory-1 (Mission ended early due to a problem with one of Columbias fuel cells.)
11	Columbia	STS-94 STS-94 STS-94 was a mission of the United States Space Shuttle Columbia, launched on 1 July 1997.-Crew:-Mission parameters:*Mass:**Orbiter Landing with payload: **MSL-1 Spacelab Module: *Perigee: *Apogee:...	July 1, 1997	15 days, 16 hours, 45 minutes, 29 seconds	Microgravity Science Laboratory-1 (reflight of STS-83)
12	Columbia	STS-87 STS-87 STS-87 was a Space Shuttle mission launched from KSC pad 39-B on 19 November 1997. It was the 88th flight of the Space Shuttle, and the 24th flight of Columbia...	November 19, 1997	15 days, 16 hours, 35 minutes, 1 second	United States Microgravity Payload-4 SPARTAN-201
13	Columbia	STS-90 STS-90 -Backup crew:-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee: *Inclination: 39.0°*Period: 89.7 min-Mission highlights:...	April 17, 1998	15 days, 21 hours, 50 minutes, 58 seconds	Neurolab
14	Columbia	STS-107 STS-107 -Mission parameters:*Mass:**Orbiter Liftoff: **Orbiter Landing: **Payload: *Perigee: *Apogee: *Inclination: 39.0°*Period: 90.1 min- Insignia :...	January 16, 2003	15 days, 22 hours, 20 minutes, 32 seconds	SPACEHAB Research Double Module FREESTAR Freestar experiment FREESTAR, which stands for Fast Reaction Experiments Enabling Science Technology Applications and Research, was a payload of six separate experiments on the Space Shuttle Columbia....

EDO medical project

Prior to the EDO project, no shuttle had flown a mission longer than 10 days. Since space travelers may faint when they stand up (orthostatic

Orthostatic hypotension

Orthostatic hypotension, also known as postural hypotension, orthostasis, and colloquially as head rush or dizzy spell, is a form of hypotension in which a person's blood pressure suddenly falls when the person stands up or stretches. The decrease is typically greater than 20/10 mm Hg, and may be...

 intolerance) after returning to normal gravity even after short flights, and muscle strength may be reduced, the EDOMP project focused on ensuring that the crew could land the orbiter, and exit from it without help after a 16-day flight. Astronauts on 40 shuttle flights (STS-32

STS-32

STS-32 was the 33rd mission of NASA's Space Shuttle program, and the 9th launch of Space Shuttle Columbia. Launching on 9 January 1990, it marked the first time since STS-61-C that Pad A at Kennedy Space Center's Complex 39 was used for a launch; it also marked the first use of Mobile Launcher...

 through STS-72

STS-72

STS-72 was a Space Shuttle Endeavour mission to capture and return to Earth a Japanese microgravity research spacecraft known as Space Flyer Unit...

) participated in 36 EDOMP investigations. The results of these investigations were used to make rules and recommendations for 16-day flights. Several types of exercise

Physical exercise

Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness. It is performed for various reasons including strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance, as well as for the purpose of...

 devices (i.e. a treadmill

Treadmill

A treadmill is an exercise machine for running or walking while staying in one place. The word treadmill traditionally refers to a type of mill which was operated by a person or animal treading steps of a wheel to grind grain...

, a cycle ergometer, and a rower

Indoor rower

An indoor rower, or rowing machine, is a machine used to simulate the action of watercraft rowing for the purpose of exercise or training for rowing. Indoor rowing has become established as a sport in its own right...

) were among the devices and procedures developed to prevent the de-conditioning of the body that occurs during space flight. The crew transport vehicles, in which astronauts are now transported after landing, were built to enhance medical capabilities at the landing site, as well as crew comfort and safety. A database of 125 formal publications, and 299 abstracts, technical papers, and presentations, also resulted from the EDOMP. The project saw its successor in the ISS Medical Project.

Other EDO projects and studies

• Manual Apparel Cleaning System - A system for laundering selected items of clothing.
• An automated Fault Detection, Isolation, and Reconfiguration-system (FDIR) that would support the shuttles for up to 28 days.
• Extended Duration Orbiter Waste Collection System. A similar system was later added to ISS as the ISS Waste Collector Subsystem.
• Extended Duration Orbiter Regenerable CO₂ Removal System.
• Medical Extended Medical Enterprise (MEME).