The Jupiter Icy Moons Orbiter (JIMO) was a proposed NASA spacecraft designed to explore the icy moons of Jupiter. The main target was Europa, where an ocean of liquid water may harbor alien life. Ganymede and Callisto, which are now thought to also have liquid, salty oceans beneath their icy surfaces, were also targets of interest for the probe.
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 via either the High Power Electric Propulsion or NEXIS engine, and powered by a small fission reactor. A Brayton power conversion system would convert reactor heat into electricity. Providing a thousand times the electrical output of conventional solar- or radioisotope thermoelectric generator (RTG)-based power systems, the reactor was expected to open up opportunities like flying a full scale ice-penetrating radar system and providing a strong, high-bandwidth data transmitter.
Using electric propulsion (8 ion engines, plus Hall thrusters of varying sizes) would make it possible to go into and leave orbits around the moons of Jupiter, creating more thorough observation and mapping windows than exist for 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 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 radionuclides that must be launched into orbit is minimized. This configuration is thought to be less risky than the RTGs used on previous missions to the outer Solar System.
The Europa Lander Mission proposed to include on JIMO a small nuclear-powered Europa lander. It would travel with the orbiter, which would also function as a communication relay to Earth. [1] It would investigate Europa's habitability and assess its astrobiological potential by confirming the existence and determining the characteristics of water within and below Europa's icy shell. [2]
Northrop Grumman was selected on September 20, 2004 for a US$400 million preliminary design contract, beating Lockheed Martin and Boeing IDS. The contract was to have run through to 2008. Separate contracts, covering construction and individual instruments, were to be awarded at a later date.
The JIMO mission was proposed to include a nuclear electric propulsion system for the long-duration mission, with power provided by a small 200 kWe fission power system. The nuclear propulsion program was conducted from 2003 to 2005 by the Naval Reactors branch of the DOE. [4]
The proposed system design was a gas-cooled reactor and Brayton power conversion to generate a peak output of 200 kilowatts of power over the long life of the JIMO mission. [4]
Three launches were planned for May 2015 to LEO in order to assemble the two transfer stages and the probe. Transfer stages were designed to launch the probe on its trajectory to Jupiter during the launch window extending from late October 2015 to mid-January 2016.
During the first month of flight, the probe's main structures would be deployed, the nuclear reactor activated, and the thrusters tested. The interplanetary flight would have lasted until April 2021 (the ion engines were supposed to work two-thirds of the time).
Once the probe was in the influence area of Jupiter, the navigation would become more complex and difficult. The probe would have to use gravity assist maneuvers to enter orbit.
The probe would have studied Callisto and then Ganymede for three months each, and finally Europa for one month (studies of Io were also planned when the orbital conditions would have been favorable).
At the end of the mission in September 2025, the vehicle would have been parked in a stable orbit around Europa.
Due to a shift in priorities at NASA that favored crewed 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. [5] Engineers at the Jet Propulsion Laboratory with JIMO were laid off or reassigned during the spring and summer of 2005.[ citation needed ]
As a result of the budget changes, NASA is[ when? ] instead considering a demonstration mission to a target closer to Earth to test out the reactor and heat rejection systems. The spacecraft would possibly be scaled down from its original size as well.[ citation needed ]
When it was cancelled, the JIMO mission was in an early planning stage and launch wasn't expected before 2017. It was to be the first proposed mission of NASA's Project Prometheus, a program for developing nuclear fission into a means of spacecraft propulsion.
After JIMO, NASA and ESA planned a joint mission to Jupiter's moons, the Europa Jupiter System Mission. This mission was also cancelled in 2011.
ESA has since continued to work separately on that design and on May 2, 2012 selected the Jupiter Icy Moon Explorer (JUICE) mission over two other ESA missions for funding. The JUICE mission will study the Jupiter moons Europa, Callisto and Ganymede and was launched as an ESA L-class mission on April 14, 2023 on an Ariane 5 carrier rocket.
In the late 2010s, the Europa Clipper became the main NASA mission to Europa with a significant difference in that it would be solar-powered and engage in multiple flybys of the moon rather than orbit it. Another similar mission is the Europa Lander, a proposed NASA astrobiology mission Europa, to complement Europa Clipper. Europa Clipper is planned to be launched in 2024 [6] and Europa Lander is planned to be launched in 2025. [7]
Galileo was an American robotic space program that studied the planet Jupiter and its moons, as well as several other Solar System bodies. Named after the Italian astronomer Galileo Galilei, the Galileo spacecraft consisted of an orbiter and an atmospheric entry probe. It was delivered into Earth orbit on October 18, 1989, by Space ShuttleAtlantis on the STS-34 mission, and arrived at Jupiter on December 7, 1995, after gravity assist flybys of Venus and Earth, and became the first spacecraft to orbit Jupiter. The spacecraft then launched the first probe to directly measure its atmosphere. Despite suffering major antenna problems, Galileo achieved the first asteroid flyby, of 951 Gaspra, and discovered the first asteroid moon, Dactyl, around 243 Ida. In 1994, Galileo observed Comet Shoemaker–Levy 9's collision with Jupiter.
A fusion rocket is a theoretical design for a rocket driven by fusion propulsion that could provide efficient and sustained acceleration in space without the need to carry a large fuel supply. The design requires fusion power technology beyond current capabilities, and much larger and more complex rockets.
Callisto, or Jupiter IV, is the second-largest moon of Jupiter, after Ganymede. In the Solar System it is the third-largest moon after Ganymede and Saturn's largest moon Titan, and as large as the smallest planet Mercury, though only about a third as massive. Callisto is, with a diameter of 4,821 km, roughly a third larger than Earth's Moon and orbits Jupiter on average at a distance of 1,883,000 km, which is about six times further out than the Moon orbiting Earth. It is the outermost of the four large Galilean moons of Jupiter, which were discovered in 1610 with one of the first telescopes, being visible from Earth with common binoculars.
Europa, or Jupiter II, is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet of all the 95 known moons of Jupiter. It is also the sixth-largest moon in the Solar System. Europa was discovered independently by Simon Marius and Galileo Galilei and was named after Europa, the Phoenician mother of King Minos of Crete and lover of Zeus.
Ganymede, or Jupiter III, is the largest and most massive natural satellite of Jupiter and in the Solar System. It is the largest Solar System object without a substantial atmosphere, despite being the only moon in the Solar System with a substantial magnetic field. Like Titan, Saturn's largest moon, it is larger than the planet Mercury, but has somewhat less surface gravity than Mercury, Io, or the Moon due to its lower density compared to the three.
Project Prometheus was established in 2003 by NASA to develop nuclear-powered systems for long-duration space missions. This was NASA's first serious foray into nuclear spacecraft propulsion since the cancellation of the SNTP project in 1995. The project was planned to design, develop, and fly multiple deep space missions to the outer planets.
An interstellar probe is a space probe that has left—or is expected to leave—the Solar System and enter interstellar space, which is typically defined as the region beyond the heliopause. It also refers to probes capable of reaching other star systems.
Juno is a NASA space probe orbiting the planet Jupiter. It was built by Lockheed Martin and is operated by NASA's Jet Propulsion Laboratory. The spacecraft was launched from Cape Canaveral Air Force Station on August 5, 2011 UTC, as part of the New Frontiers program. Juno entered a polar orbit of Jupiter on July 5, 2016, UTC, to begin a scientific investigation of the planet. After completing its mission, Juno will be intentionally deorbited into Jupiter's atmosphere.
The exploration of Jupiter has been conducted via close observations by automated spacecraft. It began with the arrival of Pioneer 10 into the Jovian system in 1973, and, as of 2023, has continued with eight further spacecraft missions in the vicinity of Jupiter. All of these missions were undertaken by the National Aeronautics and Space Administration (NASA), and all but two were flybys taking detailed observations without landing or entering orbit. These probes make Jupiter the most visited of the Solar System's outer planets as all missions to the outer Solar System have used Jupiter flybys. On 5 July 2016, spacecraft Juno arrived and entered the planet's orbit—the second craft ever to do so. Sending a craft to Jupiter is difficult, mostly due to large fuel requirements and the effects of the planet's harsh radiation environment.
TAU was a proposed uncrewed interstellar probe that would go to a distance of one thousand astronomical units from the Earth and Sun by the NASA Jet Propulsion Laboratory in 1987 using tested technology. One scientific purpose would be to measure the distance to other stars via stellar parallax. Studies continued into 1990, working with a launch in the 2005–2010 timeframe.
The Europa Orbiter was a planned NASA mission to Jupiter's Moon Europa, that was cancelled in 2002. Its main objectives included determining the presence or absence of a subsurface ocean and identifying candidate sites for future lander missions. Europa Orbiter received pre-project funding in 1998, and resulted from NASA's Fire and Ice project.
The Europa Jupiter System Mission – Laplace (EJSM-Laplace) was a proposed joint NASA/ESA uncrewed space mission slated to launch around 2020 for the in-depth exploration of Jupiter's moons with a focus on Europa, Ganymede and Jupiter's magnetosphere. The mission would have comprised at least two independent elements, NASA's Jupiter Europa Orbiter (JEO) and ESA's Jupiter Ganymede Orbiter (JGO), to perform coordinated studies of the Jovian system.
The Jupiter Magnetospheric Orbiter is a cancelled space probe proposed by the Japanese Aerospace Exploration Agency (JAXA), to undertake detailed in situ studies of the magnetosphere of Jupiter as a template for an astrophysical magnetised disk.
Jupiter Ganymede Orbiter (JGO) was a part of the international Europa Jupiter System Mission (EJSM). It was a proposed orbiter by the ESA slated for lift-off in 2020. Plans for the mission include detailed studies of Jupiter's moons Ganymede and Callisto as well as the Jovian magnetosphere.
Laplace-P was a proposed orbiter and lander by the Russian Federal Space Agency designed to study the Jovian moon system and explore Ganymede with a lander.
The Jupiter Icy Moons Explorer is an interplanetary spacecraft on its way to orbit and study three icy moons of Jupiter: Ganymede, Callisto, and Europa. These planetary-mass moons are planned to be studied because they are thought to have beneath their frozen surfaces significant bodies of liquid water, which would make them potentially habitable for extraterrestrial life.
Nuclear power in space is the use of nuclear power in outer space, typically either small fission systems or radioactive decay for electricity or heat. Another use is for scientific observation, as in a Mössbauer spectrometer. The most common type is a radioisotope thermoelectric generator, which has been used on many space probes and on crewed lunar missions. Small fission reactors for Earth observation satellites, such as the TOPAZ nuclear reactor, have also been flown. A radioisotope heater unit is powered by radioactive decay and can keep components from becoming too cold to function, potentially over a span of decades.
Europa Clipper is a space probe in development by NASA. Planned for launch in October 2024, the spacecraft is being developed to study the Galilean moon Europa through a series of flybys while in orbit around Jupiter.It is the largest spacecraft NASA has ever developed for a planetary mission.
The Europa Lander is a proposed astrobiology mission concept by NASA to send a lander to Europa, an icy moon of Jupiter. If funded and developed as a large strategic science mission, it would be launched in 2027 to complement the studies by the Europa Clipper orbiter mission and perform analyses on site.
Tianwen-4, formerly known as Gan De, is a planned Chinese interplanetary mission to study the Jovian system, possibly sharing a launch with a spacecraft which will make a flyby of Uranus.
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