
The Space Transportation System (STS), also known internally to
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeedi ...
as the Integrated Program Plan (IPP),
was a proposed system of reusable crewed
space vehicles
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider ...
envisioned in 1969 to support extended operations beyond the
Apollo program. (NASA appropriated the name for its
Space Shuttle Program
The Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. I ...
, the only component of the proposal to survive Congressional funding approval). The purpose of the system was two-fold: to reduce the cost of
spaceflight
Spaceflight (or space flight) is an application of astronautics to fly spacecraft into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in o ...
by replacing the current method of launching
capsules on expendable rockets with reusable
spacecraft
A spacecraft is a vehicle or machine designed to spaceflight, fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth ...
; and to support ambitious follow-on programs including permanent orbiting
space station
A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station ...
s around
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...
and the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width ...
, and a human landing mission to
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
.
In February 1969, President
Richard Nixon
Richard Milhous Nixon (January 9, 1913April 22, 1994) was the 37th president of the United States, serving from 1969 to 1974. A member of the Republican Party, he previously served as a representative and senator from California and was t ...
appointed a Space Task Group headed by Vice President
Spiro Agnew to recommend human space projects beyond Apollo. The group responded in September with the outline of the STS, and three different program levels of effort culminating with a human Mars landing by 1983 at the earliest, and by the end of the twentieth century at the latest. The system's major components consisted of:
* A permanent
space station
A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station ...
module designed for 6 to 12 occupants, in a
low Earth orbit
A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never m ...
, and as a permanent lunar orbit station. Modules could be combined in Earth orbit to create a 50 to 100 person permanent station.
* A chemically fueled Earth-to-orbit
shuttle
The original meaning of the word shuttle is the device used in weaving to carry the weft. By reference to the continual to-and-fro motion associated with that, the term was then applied in transportation and then in other spheres. Thus the word ma ...
.
* A chemically fueled
space tug to move crew and equipment between Earth orbits as high as
geosynchronous orbit
A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbit ...
, which could be adapted as a lunar orbit-to-surface shuttle.
* A
nuclear-powered shuttle or ferry using the
NERVA engine, to move crew, spacecraft and supplies between low Earth orbit and lunar orbit, geosynchronous orbit, or to other planets in the solar system. A crew module derived from the space station module would be used to send humans to the Moon or Mars.
The tug and ferry vehicles would be of a modular design, allowing them to be clustered and/or
staged for large payloads or interplanetary missions. The system would be supported by permanent Earth and lunar orbital
propellant depot
An orbital propellant depot is a cache of propellant that is placed in orbit around Earth or another body to allow spacecraft or the transfer stage of the spacecraft to be fueled in space. It is one of the types of space resource depots that h ...
s.
[Space Task Group Report, "Program Objectives", 4.b.] The
Saturn V
Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, with three stages, and powered with liquid fuel. It was flown from 1 ...
might still have been used as a
heavy lift launch vehicle for the nuclear ferry and space station modules. A special "
Mars Excursion Module" would be the only remaining vehicle necessary for a human
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
landing.
The STS was championed by NASA Administrator
Thomas O. Paine until May 1969 and gained Agnew's enthusiastic support. However, as Apollo accomplished its objective of landing the first humans on the Moon, Nixon realized that political support for further crewed space activities was beginning to wane, and the Congress would be unwilling to provide funding for most of these extended activities. Based on this, Nixon rejected all parts of the program except the
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
, which inherited the STS name. Nixon accepted Paine's resignation in July 1970 and replaced him as administrator with
James C. Fletcher.
As a result of funding constraints, Shuttle was significantly scaled back from its planned degree of reusability. The overall program scheduled was also delayed. The Shuttle first flew in
1981
Events January
* January 1
** Greece enters the European Economic Community, predecessor of the European Union.
** Palau becomes a self-governing territory.
* January 10 – Salvadoran Civil War: The FMLN launches its first major off ...
, and was
retired in
2011.
A second part of the system,
Space Station Freedom, was approved in the early 1980s and announced in 1984 by president
Ronald Reagan. However, this also became politically unviable by 1993, and was replaced with the
International Space Station
The International Space Station (ISS) is the largest Modular design, modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos ( ...
(ISS), with substantial contribution by
Russia
Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eigh ...
. The ISS was completed in 2011.
1969 Space Task Group
System vehicles
Earth-to-orbit shuttle
Space tug

The MSFC space tug was designed to handle a number of missions including satellite repair, transfer to
geosynchronous orbit
A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbit ...
, and as the name implies, towing payloads to the nuclear shuttle. Its modular design was centered around a cylindrical propulsion module, with an attachable crew module, cargo module, and lunar landing legs to convert it to a lunar orbit-to-surface shuttle.
Nuclear ferry

Planned uses for NERVA included a visit to
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
by 1978 and a permanent
lunar base by 1981.
[ ] NERVA rockets would be used for nuclear "tugs" designed to take payloads from Low Earth Orbit to larger orbits, resupply of several
space station
A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station ...
s in various orbits around the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...
and
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width ...
, and support for a permanent lunar base. The NERVA rocket would also be used in the Saturn S-N, an upper stage for the
Saturn V
Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, with three stages, and powered with liquid fuel. It was flown from 1 ...
rocket' upgrading the Saturn's
low Earth orbit
A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never m ...
(LEO) capability to .
Space station module
Projected program cost
References
Further reading
*
* Compton, W.D. and Charles D. Benson,
NASA SP-4208 Living and Working in Space: A History of Skylab' (1983) Chapters 5 and 6 mention 1969 Space Task Group's plan leading to a crewed Mars landing by 2000
* Heppenheimer, T.A
Washington, DC: National Aeronautics and Space Administration, 1999.
*
* NASA Report, Technical Study for the Use of the Saturn 5, INT-21 and Other Saturn 5 Derivatives to Determine an Optimum Fourth Stage (space tug). Volume 1: Technical Volume, Book 1, Web Address when accessed: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810065609_1981065609.pdf
*Dewar, James. "To The End Of The Solar System: The Story Of The Nuclear Rocket", Apogee, December 2003.
External links
*
{{NASA space program
NASA programs