Jupiter Icy Moons Orbiter

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Jupiter Icy Moons Orbiter

The Jupiter Icy Moons Orbiter (JIMO) was a proposed spacecraft

Spacecraft

A spacecraft is a Craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters outer space then returns to the Earth....
designed to explore the icy moons of Jupiter. The main target was Europa

Europa (moon)

'Europa' is the Moons_of_Jupiter#Table Natural satellite of the planet Jupiter. Europa was discovered in 1610 by Galileo Galilei , and named after a mythical Phoenician noblewoman, Europa , who was courted by Zeus and became the queen of Crete....
, the suspected ocean of which is one of the places where simple alien life is a possibility in our solar system.

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The Jupiter Icy Moons Orbiter (JIMO) was a proposed spacecraft

Spacecraft

Europa (moon)

Ganymede (moon)

'Ganymede' is a Moons of Jupiter and the List of natural satellites by diameter in the Solar System. Completing an orbit in a little more than seven days, it is the seventh satellite and third Galilean satellite from Jupiter....
and Callisto

Callisto (moon)

'Callisto' is a natural satellite of the planet Jupiter , discovered in 1610 by Galileo Galilei. It is the List of natural satellites by diameter in the Solar System and the second largest in the Jovian system, after Ganymede ....
, which are now thought to have liquid, salty oceans beneath their icy surfaces, were also targets of interest for the probe.

The JIMO spacecraft

JIMO was to have a large number of revolutionary features. Throughout its main voyage to the Jupiter moons, it was to be propelled by an ion propulsion system called HiPEP, and powered by a small fission reactor

Nuclear reactor

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an explosion....
. A Brayton

Brayton cycle

The Brayton cycle is a thermodynamic cycle that describes the workings of the gas turbine engine, basis of the jet engine and others. It is named after George Brayton , the American engineer who developed it, although it was originally proposed and patented by Englishman John Barber in 1791....
power conversion system would convert reactor heat into electricity. Providing a thousand times the electrical output of conventional solar

Solar cell

A solar cell or photovoltaic cell is a device that converts sunlight directly into electricity by the photovoltaic effect. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the source is unspecified....
or RTG

Radioisotope thermoelectric generator

A radioisotope thermoelectric generator is an electrical generator which obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactivity material is converted into electricity by the Seebeck effect using an array of thermocouples....
based power system, the reactor was expected to open up opportunities like flying a full scale ice-penetrating radar

Radar

Radar is a system that uses electromagnetic radiation waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain....
system and providing a strong, high-bandwidth data

DATA

Debt, AIDS, Trade in Africa is a multinational Non-governmental organization founded in January 2002 in London by U2's Bono along with Robert Sargent Shriver III and activists from the Jubilee 2000 Drop the Debt campaign....
transmitter.

Using electric propulsion (8 ion engines, plus Hall thrusters

Hall effect thruster

In spacecraft propulsion, a Hall thruster is a type of ion thruster in which the propellant is accelerated by an electric field. Hall thrusters trap electrons in a magnetic field and then use the electrons to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the ions in the plume....
of varying sizes) would make it possible to go into and leave orbits around Jupiter's moons, creating more thorough observation and mapping windows than exist for the current spacecraft, which must make short fly-by maneuvers because of limited fuel for maneuvering.

The design called for the reactor to be positioned in the tip of the spacecraft behind a strong radiation

Particle radiation

Particle radiation is the radiant energy of energy by means of fast-moving subatomic particles. Particle radiation is referred to as a particle beam if the particles are all moving in the same direction, similar to a light beam....
shield protecting sensitive spacecraft equipment. The reactor would only be powered up once the probe was well out of Earth orbit, so that the amount of radionuclide

Radionuclide

A radionuclide is an atom with an unstable Atomic nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron ....
s that must be launched into orbit is minimized. This configuration is thought to be less risky than the radioisotope thermoelectric generator

Radioisotope thermoelectric generator

A radioisotope thermoelectric generator is an electrical generator which obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactivity material is converted into electricity by the Seebeck effect using an array of thermocouples....
s (RTGs) used on previous missions to the outer solar system

Solar System

The Solar System consists of the Sun and those Astronomical object bound to it by gravity: the eight planets and five dwarf planets, their 173 known Natural satellite, and billions of Small Solar System body....
.

Northrop Grumman

Northrop Grumman

Northrop Grumman Corporation is an aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company is the fourth largest defense contractor in the world, and the largest builder of Naval ship....
was selected on September 20, 2004 for a $400 million preliminary design contract, beating Lockheed Martin

Lockheed Martin

Lockheed Martin is a large Multinational corporation aerospace manufacturer and advanced technology company formed in 1995 by the Horizontal integration of Lockheed with Martin Marietta....
and Boeing IDS

Boeing Integrated Defense Systems

Boeing Integrated Defense Systems , based in St. Louis, Missouri, Missouri, USA, is a unit of Boeing responsible for Arms industry and aerospace products and services....
. The contract was to have run through to 2008. Separate contracts, covering construction and individual instruments, were to be awarded at a later date.

Preliminary design specifications

Science payload mass: 1,500 kg
Electric turboalternators: multiple 104 kW (440 V AC)
Deployable radiator: 422 m² surface area
Electric Herakles ion thrusters: multiple 30 kW high efficiency, specific impulse 7,000 s (69 kN·s/kg)
Hall thrusters: high power, higher thrust
Telecommunications link: 10 Mbit/s (4×250 watt TWTA)
Deployed size: 58.4 m long × 15.7 m wide
Stowed size: 19.7 m long × 4.57 m wide
Mission design life: 20 years
Launch date: 2017
Launch Vehicle: Delta 4H
Delta IV rocket

Delta IV is an active expendable launch system in the Delta rocket family. Delta IV uses rockets designed by Boeing's Boeing Integrated Defense Systems and built in the United Launch Alliance facility in Decatur, Alabama....

Cancellation

Due to a shift in priorities at NASA

NASA

The National Aeronautics and Space Administration is an agency of the Federal government of the United States, responsible for the nation's public list of space agencies....
that favored manned space missions, the project lost funding in 2005, effectively cancelling the JIMO mission. Among other issues, the proposed nuclear technology was deemed too ambitious, as was the multiple-launch and in-orbit assembly mission architecture. Engineers at the Jet Propulsion Laboratory with JIMO were laid off or reassigned during the spring and summer of 2005.

As a result of the budget changes, NASA is instead considering a demonstration mission to a target closer to Earth

Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
to test out the reactor and heat rejection systems. The spacecraft would possibly be scaled down from its original size as well.

When it was cancelled, the JIMO mission was in its early planning stage and launch wasn't expected before 2017. It was to be the first proposed mission of NASA's Project Prometheus

Project Prometheus

Project Prometheus was established in 2003 by NASA to develop Nuclear power systems for long-duration space missions. This is NASA's first serious foray into Nuclear propulsion since the cancellation of the NERVA project in 1972....
, a program for developing nuclear fission

Nuclear fission

In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the atomic nucleus of an atom splits into smaller parts, often producing free neutrons and lighter atomic nucleus, which may eventually produce photons ....
into a viable means of spacecraft propulsion

Spacecraft propulsion

Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research....
.

Europa Jupiter System Mission

Europa Jupiter System Mission

The Europa Jupiter System Mission is a proposed joint ESA/NASA unmanned space mission for the in-depth exploration of Jupiter's moons with a focus on Europa , Ganymede and Jupiter's magnetosphere; its working name at ESA is Laplace....
is a currently planned NASA/ESA mission to Jupiters moons.

Jupiter Icy Moons Orbiter

The JIMO spacecraft

Preliminary design specifications

Cancellation

External links