Europa Clipper

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Europa Clipper
Artist rendering of the Europa Clipper mapping the surface of Europa
NASA/JPL-Caltech rendering of the proposed Europa Clipper space probe.
Operator JPL/APL
Mission type Multiple flybys of Europa while in Jupiter orbit
Launch date 2025 (proposed)[1][2]
Launch vehicle Atlas V 551 or SLS[3]
Mission duration Cruise: 6.4 years
(Atlas V and VEEGA)
or
Cruise: 1.9 years[4]
(SLS direct)
Science: 3.5 years[5]
Orbits 32 [6] to 48 [3]
Homepage Europa Clipper - NASA Jet Propulsion Laboratory
Power 150W from MMRTG or Solar cells [7]

Europa Clipper is a mission concept under study by NASA that would conduct detailed reconnaissance of Jupiter's moon Europa and would investigate whether it has conditions suitable for life.[5][6][8]

The mission name is a reference to the lightweight clipper ships of the 19th century that routinely plied trade routes around the world.[6]

History[edit]

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, other than the Earth, that could possibly harbor microbial extraterrestrial life.[3][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 $1.6B mission concept), the Jupiter Europa Orbiter (a $4.3B concept), an orbiter ($2B concept), and a multi-flyby spacecraft: Europa Clipper.[11] The proposal and scope of the Europa Clipper mission are still in the conceptual stage, but the approximate cost is estimated at $2 billion.[3][10] Meanwhile, the European Space Agency is already developing the Jupiter Icy Moon Explorer for a proposed launch in 2022.[12]

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,[13] as suggested in 2011 by the Planetary Science Decadal Survey.[4][10] In May 2014, a House bill substantially increased Europa Clipper funding budget for the 2014 fiscal year from $15 million[1][2] to $100 million.[14][15] 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),[4] who presented an updated concept for Europa Clipper in July 2013.[16]

Following the 2014 election cycle, bipartisan support was pledged to continue funding for the Europa Clipper project.[17]

Objectives[edit]

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.[8][18][19] Specifically, the objectives are to study:[16]

  • 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 between 32 to 48 flybys of Europa[8] at altitudes from 25 to 100 km each during its mission.[5] Each flyby will cover a different sector of Europa in order to achieve a medium-quality global topographic survey, including ice thickness.[8] 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.[1][2] 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.[5]

Strategy[edit]

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.[11] 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.[11] 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.[11]

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.[11] Between each of the flybys, the multi-flyby spacecraft would have seven to ten days to transmit data stored during each brief encounter. That would let the multi-flyby craft 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.[11]

Scientific payload[edit]

The concept for the operation of the science instruments on-board Europa Clipper during a Europa flyby. (Courtesy NASA/JPL-Caltech)

The spacecraft, trajectory and payload are subject to change as the design matures. The eight science instruments under consideration, with a calculated total mass of 82.3 kg are:[6][8][20]

  • Shortwave Infrared Spectrometer (SWIRS) can identify materials exposed on Europa's surface and map their distribution, and eventually study it with a lander.
  • Ice-penetrating radar (IPR) would determine the thickness of the ice, study whether bodies of water are trapped within the ice between the surface and the ocean below, study fracturing of the shell and help understand how material is transported between the ocean and the surface.
  • Stereo Topographical Imager (TI) to map the surface.
  • Neutral Mass Spectrometer (NMS) to elucidate the chemical structures of molecules on the surface, and to analyze the moon's trace atmosphere during flybys
  • Magnetometer[8] would characterize the magnetic field and gravity of Europa.
  • Langmuir probes[8] would measure the plasma field around Europa.
  • Reconnaissance Camera (RC) to acquire surface images in the visible spectrum.
  • Thermal Imager (ThI) to map temperature at the surface.[21]
Nanosatellites

The scientists proposing this mission are also considering deploying from the spacecraft several miniaturized satellites of the CubeSat type, possibly driven by xenon thrusters, to sample and analyse Europa's plumes.[5][8][22] Europa Clipper will relay signals from the satellites with its high gain antenna back to Earth. With propulsion, some nanosatellites will be capable of entering orbit around Europa.[8] 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.[8]

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.[8]

Power[edit]

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.[7] 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.[8]

A more reliable alternative to solar panels is Multi-Mission Radioisotope Thermoelectric Generators, fueled with plutonium-238.[5][8] 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, a restart of plutonium production and replacement of the equipment needed to press it into pellets, it would be feasible to use MMRTGs on Europa Clipper.[8][23]

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.[5]

See also[edit]

References[edit]

  1. ^ a b c Wall, Mike (5 March 2014). "NASA hopes to launch ambitious mission to icy Jupiter moon". Space.com. Retrieved 2014-04-15. 
  2. ^ a b c Clark, Stephen (14 March 2014). "Economics, water plumes to drive Europa mission study". Spaceflight Now. Retrieved 2014-04-15. 
  3. ^ a b c d Dreier, Casey (12 December 2013). "Europa: No Longer a "Should," But a "Must"". The Planetary Society. 
  4. ^ a b c Leone, Dan (22 July 2013). "NASA's Europa Mission Concept Progresses on the Back Burner". Space News. 
  5. ^ a b c d e f g 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. 
  6. ^ a b c d "Europa Clipper". Jet Propulsion Laboratory (NASA). November 2013. 
  7. ^ a b Dreier, Casey (5 September 2013). "NASA's Europa Mission Concept Rejects ASRGs -- May Use Solar Panels at Jupiter Instead". The Planetary Society. 
  8. ^ a b c d e f g h i j k l m n Kane, Van (26 May 2013). "Europa Clipper Update". Future Planetary Exploration. 
  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 on 2006-07-03. 
  10. ^ a b c Zabarenko, Deborah (7 March 2011). "Lean U.S. missions to Mars, Jupiter moon recommended". Reuters. 
  11. ^ a b c d e f Kane, Van (26 August 2014). "Europa: How Less Can Be More". Planetary Society. Retrieved 2014-08-29. 
  12. ^ "ESA—Selection of the L1 mission". April 17, 2012. 
  13. ^ "Destination: Europa". Europa SETI. 29 March 2013. 
  14. ^ Zezima, Katie (8 May 2014). "House gives NASA more money to explore planets". Washington Post. Retrieved 2014-05-09. 
  15. ^ Morin, Monte (8 May 2014). "$17.9-billion funding plan for NASA would boost planetary science". Los Angeles Times. Retrieved 2014-05-09. 
  16. ^ a b Pappalardo, Robert; Cooke, Brian; Goldstein, Barry; Prockter, Louise; Senske, Dave; Magner, Tom (July 2013). "OPAG Update" (PDF). Lunar and Planetary Institute.  |chapter= ignored (help)
  17. ^ http://www.space.com/27660-jupiter-moon-europa-exploration-congress.html
  18. ^ Pappalardo, Robert T.; Vance, S.; Bagenal, F.; Bills, B.G.; Blaney, D.L.; Blankenship, D.D.; Brinckerhoff, W.B.; et al.; Hand, K.P.; Hoehler, T.M.; Leisner, J.S.; Kurth, W.S.; McGrath, M.A.; Mellon, M.T.; Moore, J.M.; Patterson, G.W.; Prockter, L.M.; Senske, D.A.; Schmidt, B.E.; Shock, E.L.; Smith, D.E.; Soderlund, K.M. (2013). "Science Potential from a Europa Lander". Astrobiology 13 (8): 740. doi:10.1089/ast.2013.1003. PMID 23924246. Retrieved 2013-12-14. 
  19. ^ Senske, D. (2 October 2012). "Presentation to Planetary Science Subcommittee" (PDF).  |chapter= ignored (help)
  20. ^ Lewis, Kari; Klaasen, Ken (March 19, 2014). "Europa Clipper Pre-Project" (PDF). Update to ICEE Teams. NASA. 
  21. ^ Senske, D. A.; Pappalardo, R. T.; Prockter, L.; Vance, S. (2014). "Investigating icy world habitability through the Europa Clipper mission concept" (PDF). Workshop on the Habitability of Icy Worlds (2014). 
  22. ^ Grossman, Lisa (4 January 2014). "Water plumes spark a race to Europe" (PDF). New Scientist: page 10. Retrieved 2014-05-06. 
  23. ^ Leone, Dan (28 July 2014). "Europa Clipper Would Wash Out Other Nuclear-powered Missions". Space News. Retrieved 2014-08-29.