Europa Multiple-Flyby Mission

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Europa Multiple-Flyby Mission
Europa Mission Transparent.png
Concept artwork of the Europa Multiple-Flyby Mission spacecraft
Names Europa Clipper (2012-15)
Mission type Europa reconnaissance
Operator NASA
Mission duration Cruise: 6.4 years (Atlas V), or
Cruise: 1.9 years (SLS Block I)[1]
Science: 3.5 years[2]
Spacecraft properties
Manufacturer Jet Propulsion Laboratory
Power 600W from solar cells[3]
Start of mission
Launch date Between 2022 & 2025 (Between 2022 & 2025)[4][5]
Rocket Atlas V 551 or SLS Block I[6]
Jupiter orbiter
Orbits 45[7]

The Europa Multiple-Flyby Mission[8] (formerly known as the Europa Clipper) is an interplanetary space probe in development by NASA. Set for a launch in the 2020s, the spacecraft is being developed to study the Galilean moon Europa, through a series of flybys while in orbit around Jupiter.

The mission is a follow-up to studies made by the Galileo spacecraft during its eight years in Jupiter orbit, which indicated the existence of a subsurface ocean underneath Europa. Plans to send a spacecraft to Europa were initially conceived with projects such as Europa Orbiter and Jupiter Icy Moons Orbiter, in which a spacecraft would be injected into orbit around Europa. However, due to the strong impact of radiation from Jupiter's magnetosphere in Europan orbit, it was decided that it would be safer to inject a spacecraft into an orbit around Jupiter and make several close flybys of the moon instead. The mission was originally branded the Europa Clipper mission, and began as a joint investigation between the Jet Propulsion Laboratory and the Applied Physics Laboratory.

The Europa Mission spacecraft will be built and manufactured with a scientific payload of nine instruments, contributed by the JPL, APL, Southwest Research Institute, University of Texas, Arizona State University and University of Colorado Boulder. Two possibilities for transfer to Jupiter have been considered: one, using an Atlas V 551 to launch the spacecraft into a trajectory that will make use of multiple gravity assists from Earth and Venus, and the other using the Space Launch System to launch the spacecraft directly towards Jupiter.


Multiple flybys of Europa by a previous mission collected the data for this mosaic

Europa has been identified as one of the locations in the Solar System that could possibly harbor microbial extraterrestrial life.[6][9][10]

Immediately following the Galileo spacecraft's discoveries, JPL conducted preliminary mission studies that envisioned a capable spacecraft such as the Jupiter Icy Moons Orbiter (a $16B mission concept[11] ), the Jupiter Europa Orbiter (a $4.3B concept), an orbiter ($2B concept), and a multi-flyby spacecraft: Europa Clipper.[12] The proposal and scope of the Europa Clipper mission are still in the conceptual stage, but the approximate cost is estimated at $2 billion.[6][10] Meanwhile, the European Space Agency is already developing the Jupiter Icy Moon Explorer for a proposed launch in 2022.[13]

In March 2013, $75 million USD were authorized to expand on the formulation of mission activities, mature the proposed science goals, and fund preliminary instrument development,[14] as suggested in 2011 by the Planetary Science Decadal Survey.[1][10] In May 2014, a House bill substantially increased Europa Clipper funding budget for the 2014 fiscal year from $15 million[4][5] to $100 million.[15][16] The funds would be applied to pre-formulation work.

The mission's science definition team is chaired by Louise Prockter from the Johns Hopkins University's the Applied Physics Laboratory (APL), and Barry Goldstein from the Jet Propulsion Laboratory (JPL),[1] who presented an updated concept for Europa Clipper in July 2013.[17]

Following the 2014 election cycle, bipartisan support was pledged to continue funding for the Europa Clipper project.[18][19] The executive branch has also granted such a mission $30 million for preliminary studies, the most the White House has proposed for the mission.[20][21]

In April 2015, NASA offered to the European Space Agency to submit concepts for an additional probe to fly together with the Europa Clipper spacecraft. It could be a simple probe, an impactor or a lander.[22] An internal assessment at ESA is underway to see if there is interest and funds available.[22]

In May 2015, NASA announced they had chosen the nine instruments that would fly onboard the orbiter. They will cost about $110 million over the next three years.[23]

In June 2015, NASA announced its approval of the mission concept, allowing the orbiter to move to its formulation stage.[24]


The concept to achieve "global-regional coverage" of Europa during successive flybys. (Courtesy NASA/JPL-Caltech)

The goals of the proposed Europa Clipper space probe are to explore Europa, investigate its habitability and aid in the selection of future landing sites.[25][26][27] Specifically, the objectives are to study:[17]

  • Ice shell and ocean: Confirm the existence, and characterize the nature, of water within or beneath the ice, and processes of surface-ice-ocean exchange.
  • Composition: Distribution and chemistry of key compounds and the links to ocean composition.
  • Geology: Characteristics and formation of surface features, including sites of recent or current activity.

The Europa Clipper would not orbit Europa, but instead orbit Jupiter and conduct 45 flybys of Europa at altitudes from 25 to 2700 km each during its mission.[2][28] Each flyby would cover a different sector of Europa in order to achieve a medium-quality global topographic survey, including ice thickness.[25] The Europa Clipper could conceivably flyby at low altitude through the plumes of water vapor erupting from the moon's icy crust, thus sampling its subsurface ocean without having to land on the surface and drill though the ice.[4][5] Europa's surface needs to be scouted out first; thus, the Clipper concept has as a secondary goal: to characterize scientifically compelling sites for a future lander mission to Europa.[2]


A wide orbit of Jupiter with several flybys of Europa would minimize radiation exposure and increase data transfer speed

Because Europa lies well within the harsh radiation fields surrounding Jupiter, even a radiation-hardened spacecraft in near orbit would be functional for just a few months.[12] Another key limiting factor on science for a Europa orbiter is not the time the instruments can make observations. Rather, it is the time available to return data to Earth.[12] Most instruments can gather data far faster than the communications system can transmit it to Earth, but there are a limited number of antennas available to receive the scientific data.[12]

Studies by scientists from the Jet Propulsion Laboratory show that by performing several flybys with many months to return data, the Europa Clipper concept would enable a $2B mission to conduct the most crucial measurements of the cancelled $4.3B Jupiter Europa Orbiter concept.[12] Between each of the flybys, the spacecraft would have seven to ten days to transmit data stored during each brief encounter. That would let the spacecraft have up to a year of time to transmit its data compared to just 30 days for an orbiter. The result would be almost three times as much data returned to Earth, while reducing exposure to radiation.[12]

Europa Clipper would inherit tested technology of the Galileo and Juno Jupiter orbiters with regards to radiation protection. Shielding will be provided by 150 kilograms of material. To maximize its effectiveness, the electronics will be nested in the core of the spacecraft for additional radiation protection.[25]

Design and construction[edit]


Both radioisotope thermoelectric generator and photovoltaic power sources were analyzed as possible power for the mission.[29] In September 2013 it was decided that solar panels are the least expensive option to power the spacecraft. Early analysis suggest that each panel will have a surface area of 18m2 and produce 150 watts continuously when pointed towards the Sun while at Jupiter.[30] While in Europa's shadow, batteries will enable the spacecraft to continue gathering data. However, ionizing radiation can damage solar cells. The Europa Clipper's orbit causes the spacecraft pass through Jupiter's intense magnetosphere, which is expected to gradually degrade the solar cells as the mission progresses.[25]

The alternative to solar panels considered is Multi-Mission Radioisotope Thermoelectric Generators, fueled with plutonium-238.[2][25] The power source has already been demonstrated in the Mars Science Laboratory mission. Five units are currently available, with one reserved for the Mars 2020 rover mission and another as backup. If funding becomes available, providing a restart of plutonium production and the replacement of the equipment needed to press it into pellets, it would be feasible to use MMRTGs on Europa Clipper.[25][31]

On 3 October 2014, it was announced that solar panels have been chosen to power Europa Clipper. The mission's designers have determined that, despite the fact that solar power is only 4% as intense at Jupiter as it is in Earth's orbit, solar was both cheaper than plutonium and practical to use on the spacecraft.[29] Despite the increased weight of solar panels compared to plutonium-powered generators, the vehicle's mass had been projected to still be within acceptable launch limits.[32]

Scientific payload[edit]

Artist's impression of the spacecraft's REASON instrument in action, using dual-frequency radar to map Europa's ice layer.
Photograph of the Thermal Emission Imaging System (THEMIS) instrument, as used aboard 2001 Mars Odyssey.
A photograph of Nanedi Valles by THEMIS aboard 2001 Mars Odyssey. The E-THEMIS instrument aboard the Europa Mission will produce similar quality images.

The spacecraft and trajectory are subject to change as the design matures. The nine science instruments, announced in May 2015, have an estimated total mass of 82 kg (181 lb) and are listed below:[33]

  • PIMS
The Plasma Instrument for Magnetic Sounding (PIMS)[34] works in conjunction with a magnetometer and is key to determining Europa's ice shell thickness, ocean depth, and salinity by correcting the magnetic induction signal for plasma currents around Europa.
Principal investigator: Joseph Westlake, Applied Physics Laboratory
The Interior Characterization of Europa using Magnetometry (ICEMAG) is a magnetometer that will measure the magnetic field near Europa and – in conjunction with the PIMS instrument – will probe the location, depth, thickness and salinity of Europa's subsurface ocean using multi-frequency electromagnetic sounding.[35]
Principal investigator: Carol Raymond, Jet Propulsion Laboratory
  • MISE
The Mapping Imaging Spectrometer for Europa (MISE) instrument will probe the surface composition of Europa, identifying and mapping the distributions of organics, salts, acid hydrates, water ice phases, and other materials to determine the habitability of Europa's ocean. From these measurements, scientists expect to be able to relate the moon's surface composition to the habitability of its ocean.[35][36] MISE is built in collaboration with the Johns Hopkins University Applied Physics Laboratory (APL).
Principal investigator: Diana Blaney, Jet Propulsion Laboratory
  • EIS
The Europa Imaging System (EIS) is a wide and narrow angle camera instrument that will map most of Europa at 50 m (160 ft) resolution, and will provide images of selected surface areas at up to 100 times higher resolution.
Principal investigator: Elizabeth Turtle, Applied Physics Laboratory
The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON)[37][38] is a dual-frequency ice penetrating radar instrument that is designed to characterize and sound Europa's ice crust from the near-surface to the ocean, revealing the hidden structure of Europa's ice shell and potential water pockets within. This instrument will be built by JPL and the University of Iowa.[35][37]
Principal investigator: Donald Blankenship, University of Texas
The Europa Thermal Emission Imaging System (E-THEMIS) is a "heat imager", which will provide high spatial resolution, multi-spectral thermal imaging of Europa to help detect active sites, such as potential vents erupting plumes of water into space. This instrument is derived from the Thermal Emission Imaging System (THEMIS) on 2001 Mars Odyssey orbiter, also developed by Philip Christensen.
Principal investigator: Philip Christensen, Arizona State University
The MAss SPectrometer for Planetary EXploration/Europa (MASPEX) is a spectrometer that will determine the composition of the surface and subsurface ocean by measuring Europa's extremely tenuous atmosphere and any surface material ejected into space. Jack Waite, who developed MASPEX, was selected as the Science Team Lead of the Ion and Neutral Mass Spectrometer (INMS) on Cassini spacecraft. The INMS was developed as a facility instrument at NASA Goddard Space Flight Center under the direction of Dr. Hasso Niemann.
Principal investigator: Jack Waite, Southwest Research Institute
  • UVS
The Ultraviolet Spectrograph/Europa (UVS) instrument will be able to detect small plumes and will provide valuable data about the composition and dynamics of the moon's exosphere. He discovered plumes erupting from Europa while using the Hubble Space Telescope in the UV spectrum.[39]
Principal investigator: Kurt Retherford, Southwest Research Institute
  • SUDA
The SUrface Dust Mass Analyzer (SUDA) instrument will measure the composition of small solid particles ejected from Europa, providing the opportunity to directly sample the surface and potential plumes on low-altitude flybys. The instrument is capable of reliably identifying traces of organic and inorganic materials in the ice matrix of ejecta.[40]
Principal investigator: Sascha Kempf, University of Colorado Boulder
1U CubeSat is a 10 cm (4 in) cube

The scientists proposing this mission are also considering deploying from the spacecraft several miniaturized satellites of the CubeSat format, possibly driven by ion thrusters, to sample and analyse Europa's plumes.[2][21][41] Europa Clipper would relay signals from the satellites with its high-gain antenna back to Earth. With propulsion, some nanosatellites could be capable of entering orbit around Europa.[25] However, including additional mass would only be possible if the Europa Clipper is launched with the powerful Space Launch System (SLS) heavy lift launch vehicle.[25]

Launch options[edit]

A baseline profile for the mission would involve launch aboard an Atlas V 551. By using a Venus-Earth-Earth gravity assist trajectory the transit time to Jupiter would be about 6 years. Alternately, if the mission was launched by NASA's Space Launch System, it could arrive at Jupiter on a direct trajectory in less than 3 years.[2]

See also[edit]


  1. ^ a b c Leone, Dan (22 July 2013). "NASA's Europa Mission Concept Progresses on the Back Burner". Space News. 
  2. ^ a b c d e f Phillips, Cynthia B.; Pappalardo, Robert T. (20 May 2014). "Europa Clipper Mission Concept:". Eos, Transactions American Geophysical Union 95 (20): 165–167. doi:10.1002/2014EO200002. Retrieved 2014-10-01. 
  3. ^ Goldstein, Barry; Pappalardo, Robert (19 February 2015). "Europa Clipper Update" (PDF). Outer Planets Assessment Group. 
  4. ^ a b c Wall, Mike (5 March 2014). "NASA hopes to launch ambitious mission to icy Jupiter moon". Retrieved 2014-04-15. 
  5. ^ a b c Clark, Stephen (14 March 2014). "Economics, water plumes to drive Europa mission study". Spaceflight Now. Retrieved 2014-04-15. 
  6. ^ a b c Dreier, Casey (12 December 2013). "Europa: No Longer a "Should," But a "Must"". The Planetary Society. 
  7. ^ All Systems Go for NASA's Mission to Jupiter Moon Europa. NASA News, 17 June 2015
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  9. ^ Schulze-Makuch, Dirk; Irwin, Louis N. (2001). "Alternative Energy Sources Could Support Life on Europa" (PDF). Departments of Geological and Biological Sciences. University of Texas at El Paso. Archived from the original (PDF) on 2006-07-03. 
  10. ^ a b c Zabarenko, Deborah (7 March 2011). "Lean U.S. missions to Mars, Jupiter moon recommended". Reuters. 
  11. ^ "Project Prometheus final report - page 178" (PDF). 2005. Retrieved 20 January 2015. 
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  14. ^ "Destination: Europa". Europa SETI. 29 March 2013. 
  15. ^ Zezima, Katie (8 May 2014). "House gives NASA more money to explore planets". Washington Post. Retrieved 2014-05-09. 
  16. ^ Morin, Monte (8 May 2014). "$17.9-billion funding plan for NASA would boost planetary science". Los Angeles Times. Retrieved 2014-05-09. 
  17. ^ a b Pappalardo, Robert; Cooke, Brian; Goldstein, Barry; Prockter, Louise; Senske, Dave; Magner, Tom (July 2013). "The Europa Clipper" (PDF). OPAG Update (PDF). Lunar and Planetary Institute. 
  18. ^ Nola Taylor Redd (5 November 2014). "To Europa! Mission to Jupiter's Moon Gains Support in Congress". Retrieved November 2014. 
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