''Europa Clipper''

Europa Clipper

Artist's rendering of the Europa Clipper spacecraft.
Mission type Europa reconnaissance
Operator NASA
Website jpl.nasa.gov
Mission duration Cruise: 1.9 years[1][2]
Spacecraft properties
Manufacturer Jet Propulsion Laboratory
Power 600 W from solar cells[3]
Start of mission
Launch date Around 2022 (Around 2022)[4][5]
Rocket SLS (Block IB)[6][7]
Jupiter orbiter
Orbits 45[8]

Europa Clipper[9] is an interplanetary mission in development by NASA comprising an orbiter and a lander. Set for a launch in the 2020s (around 2022),[7] the spacecraft are being developed to study the Galilean moon Europa through a lander and a series of flybys while in orbit around Jupiter. Until March 7, 2017, the mission was developed under the name Europa Multiple Flyby Mission.

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 elliptical orbit around Jupiter and make several close flybys of the moon instead. The mission has been referred to as the Europa Multiple Flyby Mission, and began as a joint investigation between the Jet Propulsion Laboratory and the Applied Physics Laboratory.

The mission will complement ESA's Jupiter Icy Moons Explorer, which will fly-by Europa twice and Callisto multiple times before moving into orbit around Ganymede. Launching around the same time as the Europa Clipper, the Jupiter Icy Moons Explorer will have a cruise phase some three times as long.

The Europa Clipper orbiter 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.

History

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.[10][11][12] 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[13]), the Jupiter Europa Orbiter (a $4.3B concept), an orbiter ($2B concept), and a multi-flyby spacecraft: Europa Clipper.[14]

The proposed Europa Clipper is still in its planning phase, but the approximate cost is estimated at $2 billion.[10][12] The mission is a joint project between the Johns Hopkins University's Applied Physics Laboratory (APL), and the Jet Propulsion Laboratory (JPL).[1][15]

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,[16] as suggested in 2011 by the Planetary Science Decadal Survey.[1][12] In May 2014, a House bill substantially increased the Europa Multiple Flyby Mission funding budget for the 2014 fiscal year from $15 million[4][5] to $100 million to be applied to pre-formulation work.[17][18]

Following the 2014 election cycle, bipartisan support was pledged to continue funding for the Europa Multiple Flyby Mission project.[19][20] The executive branch has also granted $30 million for preliminary studies.[21][22]

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.[23] An internal assessment at ESA is underway to see if there is interest and funds available,[24][25] opening a collaboration scheme similar to the very successful Cassini-Huygens approach.

In May 2015, NASA chose nine instruments that would fly on board the orbiter. They will cost about $110 million over the next three years.[26] In June 2015, NASA announced its approval of the mission concept, allowing the orbiter to move to its formulation stage,[27] and in January 2016 it approved a lander as well.[6][7]

In February 2017 the mission moved from Phase A to Phase B.[28] Phase B is the preliminary design phase of the mission.[28]

Objectives

The concept to achieve global-regional coverage of Europa during successive flybys.

The goals of Europa Clipper are to explore Europa, investigate its habitability and aid in the selection of a landing site for its lander.[7][29] Specifically, the objectives are to study:[15]

The Europa Clipper would not orbit Europa, but instead orbit Jupiter and conduct 45 flybys of Europa at altitudes from 25 to 2,700 km (16 to 1,700 mi) each during its mission.[2][30] Each flyby would cover a different sector of Europa in order to achieve a medium-quality global topographic survey, including ice thickness.[31] 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]

Strategy

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.[14] 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.[14] Most instruments can gather data far faster than the communications system can transmit it to Earth because there are a limited number of antennas available to receive the scientific data.[14]

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.[14] 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.[14]

The 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 titanium. To maximize its effectiveness, the electronics will be nested in the core of the spacecraft for additional radiation protection.[31]

Design and construction

Power

Both radioisotope thermoelectric generator and photovoltaic power sources were assessed to power the orbiter.[32] 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 18 m2 (190 sq ft) and produce 150 watts continuously when pointed towards the Sun while orbiting Jupiter.[33] While in Europa's shadow, batteries will enable the spacecraft to continue gathering data. However, ionizing radiation can damage solar panels. The Europa Clipper's orbit will pass through Jupiter's intense magnetosphere, which is expected to gradually degrade the solar panels as the mission progresses.[31]

The alternative to solar panels was a Multi-Mission Radioisotope Thermoelectric Generator, fueled with plutonium-238.[2][31] 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. On October 3, 2014, it was announced that solar panels were chosen to power Europa Clipper. The mission's designers 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.[32] 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.[34]

Scientific payload

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 payload and trajectory are subject to change as the mission design matures. While the Europa Clipper spacecraft is well equipped for Europa studies, which include plume detection and characterization, it is limited in its ability to fully analyze Europa water plumes.[35]

The nine science instruments for the orbiter, announced in May 2015, have an estimated total mass of 82 kg (181 lb) and are listed below:[36]

The Europa Thermal Emission Imaging System (E-THEMIS) will provide high spatial resolution, multi-spectral imaging of Europa in the medium- and long-wave infrared bands 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 Mapping Imaging Spectrometer for Europa (MISE) instrument will image in the short-wave infrared band to probe the surface composition of Europa, identifying and mapping the distributions of organics, salts, acid hydrates, water ice phases, and other materials to assess 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.[37][38] MISE is built in collaboration with the Johns Hopkins University Applied Physics Laboratory (APL).
Principal investigator: Diana Blaney, Jet Propulsion Laboratory
The Europa Imaging System (EIS) is a visible-spectrum 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 0.5 m resolution.
Principal investigator: Elizabeth Turtle, Applied Physics Laboratory
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. Principle Investigator Kurt Retherford was part of a group that discovered plumes erupting from Europa while using the Hubble Space Telescope in the UV spectrum.[39]
Principal investigator: Kurt Retherford, Southwest Research Institute
The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON)[40][41] 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.[37][40]
Principal investigator: Donald Blankenship, University of Texas
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.[37]
Principal investigator: Carol Raymond, Jet Propulsion Laboratory
The Plasma Instrument for Magnetic Sounding (PIMS)[42][43] measures the plasma surrounding Europa to characterise the magnetic fields generated by plasma currents. These plasma currents mask the magnetic induction response of Europa's subsurface ocean. In conjunction with the ICEMAG instrument, it is key to determining Europa's ice shell thickness, ocean depth, and salinity. PIMS will also probe the mechanisms responsible for weathering and releasing material from Europa's surface into the atmosphere and ionosphere and understanding how Europa influences its local space environment and Jupiter's magnetosphere.
Principal investigator: Joseph Westlake, Applied Physics Laboratory
The MAss SPectrometer for Planetary EXploration/Europa (MASPEX) will determine the composition of the surface and subsurface ocean by measuring Europa's extremely tenuous atmosphere and any surface materials ejected into space. Jack Waite, who led development of MASPEX, was also 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
The SUrface Dust Mass Analyzer (SUDA) mass spectrometer 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 identifying traces of organic and inorganic compounds in the ice of ejecta.[44]
Principal investigator: Sascha Kempf, University of Colorado Boulder

Additional probes

Nanosatellites
1U CubeSat is a 10 cm (4 in) cube

Since the Europa Clipper mission may not be able to easily modify its orbital trajectory or altitude to fly through the episodic water plumes, scientists and engineers working on the mission have investigated deploying from the spacecraft several miniaturized satellites of the CubeSat format, possibly driven by ion thrusters, to fly through the plumes and assess the habitability of Europa's internal ocean.[2][22][45] Some early proposals include Mini-MAGGIE,[46] DARCSIDE,[47] and Sylph.[48] The Europa Clipper would relay signals from the nanosatellites back to Earth. With propulsion, some nanosatellites could also be capable of entering orbit around Europa.[31]

Biosignature Explorer for Europa

NASA is also assessing the release of an additional 250 kg (550 lb) probe called Biosignature Explorer for Europa (BEE), that would be equipped with a basic bi-propellant engine and cold gas thrusters to be more agile and responsive to the episodic activity on Europa and sample and analyze the water plumes for biosignatures and life evidence before they are destroyed by radiation.[35] The BEE plume probe would be equipped with a proven mass spectrometer combined with gas chromatograph separation. It would also carry a UV plume targeting camera as well as visible and IR cameras to image the active region with better resolution than the Clipper mother ship instruments.[35] The BEE probe would fly through at 2–10 km altitude, then make a quick exit and perform its analysis far from the radiation belts.

Add-on lander history

An early Europa Clipper concept calls for a small lander about 1 meter in diameter, perhaps about 230 kg (510 lb) with a maximum of 30 kg (66 lb) for instruments.[7] Suggested instruments are a mass spectrometer and a Raman spectrometer to determine the chemistry of the surface.[7] The lander would be delivered to Europa by the main spacecraft and possibly require the sky crane system for a high precision, soft landing near an active crevasse.[49] The lander would operate about 10 days on the surface using battery power.[7] In January 2016 it was announced that including additional mass of a lander and detachable probes, meant the Europa Clipper will be launched with NASA's Space Launch System (SLS) heavy lift launch vehicle[6][7] that could arrive at Jupiter on a direct trajectory in less than three years.[2]

The Europa Clipper would take about three years to image 95% of the surface of Europa at about 50 meters per pixel. With this data, scientists could then find a suitable landing site.[49] By one estimate, including a lander could add as much as $1 billion to the mission's cost.[49]

Separate launch
Artist's impression of the separately launched-version of Europa lander mission (2017 design)

Eventually the desire for the lander increased until the point it became a stand-alone mission proposal: the Europa Lander.[50] The NASA Europa Lander, if selected, would be a separately launched spacecraft building on the Europa Clipper mission.[51][52]

Launch options

A baseline profile for the mission involved launch aboard an Atlas V 551. By using a Venus-Earth-Earth gravity assist trajectory the transit time to Jupiter would be about six years. The baseline design of Europa Clipper includes a launch with NASA's Space Launch System (SLS) heavy lift launch vehicle[6][7] that could arrive at Jupiter on a direct trajectory in less than three years.[2]

See also

References

  1. 1 2 3 Leone, Dan (22 July 2013). "NASA's Europa Mission Concept Progresses on the Back Burner". Space News.
  2. 1 2 3 4 5 6 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. 1 2 3 Wall, Mike (5 March 2014). "NASA hopes to launch ambitious mission to icy Jupiter moon". Space.com. Retrieved 2014-04-15.
  5. 1 2 3 Clark, Stephen (14 March 2014). "Economics, water plumes to drive Europa mission study". Spaceflight Now. Retrieved 2014-04-15.
  6. 1 2 3 4 Kornfeld, Laurel (4 January 2016). "Additional $1.3 billion for NASA to fund next Mrs rover, Europa mission". The Space Reported. Retrieved 2016-01-05.
  7. 1 2 3 4 5 6 7 8 9 Kane, Van (5 January 2016). "A Lander for NASA's Europa Mission". The Planetary Society. Retrieved 2016-01-05.
  8. ↑ All Systems Go for NASA's Mission to Jupiter Moon Europa. NASA News, 17 June 2015
  9. ↑ "Europa Multiple Flyby Mission". Solar System Exploration. National Aeronautics and Space Administration. Retrieved 9 July 2015.
  10. 1 2 Dreier, Casey (12 December 2013). "Europa: No Longer a "Should," But a "Must"". The Planetary Society.
  11. ↑ 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.
  12. 1 2 3 Zabarenko, Deborah (7 March 2011). "Lean U.S. missions to Mars, Jupiter moon recommended". Reuters.
  13. ↑ "Project Prometheus final report – page 178" (PDF). 2005. Retrieved 20 January 2015.
  14. 1 2 3 4 5 6 Kane, Van (26 August 2014). "Europa: How Less Can Be More". Planetary Society. Retrieved 2014-08-29.
  15. 1 2 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.
  16. ↑ "Destination: Europa". Europa SETI. 29 March 2013.
  17. ↑ Zezima, Katie (8 May 2014). "House gives NASA more money to explore planets". Washington Post. Retrieved 2014-05-09.
  18. ↑ Morin, Monte (8 May 2014). "$17.9-billion funding plan for NASA would boost planetary science". Los Angeles Times. Retrieved 2014-05-09.
  19. ↑ Nola Taylor Redd (November 5, 2014). "To Europa! Mission to Jupiter's Moon Gains Support in Congress". Retrieved August 31, 2016.
  20. ↑ Dreier, Casey (3 February 2015). "It's Official: We're On the Way to Europa". Retrieved 8 February 2015.
  21. ↑ Kane, Van (3 February 2015). "2016 Budget: Great Policy Document and A Much Better Budget". Retrieved 8 February 2015.
  22. 1 2 Clark, Stephen (March 10, 2015). "Europa Multiple Flyby Mission concept team aims for launch in 2022". Space Flight Now. Retrieved 2015-04-09.
  23. ↑ Clark, Stephen (10 April 2015). "NASA invites ESA to build Europa piggyback probe". Space Flight Now. Retrieved 2015-04-17.
  24. ↑ Amos, Jonathan (19 April 2016). "European scientists set eyes on ice moon Europa". BBC News. Retrieved 2016-04-19.
  25. ↑ Blanc, Michel; Jones, Geraint H.; Prieto-Ballesteros, Olga; Sterken, Veerle J. (2016). "The Europa initiative for ESA’s cosmic vision: a potential European contribution to NASA’s Europa mission" (PDF). Geophysical Research Abstracts. 18. Retrieved 2016-09-29.
  26. ↑ Klotz, Irene (26 May 2015). "NASA's Europa Mission Will Look for Life's Ingredients". Discovery News. Retrieved 2015-05-26.
  27. ↑ Howell, Elizabeth (20 June 2015). "NASA's Europa Mission Approved for Next Development Stage". Space.com. Retrieved 2015-06-21.
  28. 1 2 Greicius, Tony (2017-02-21). "NASA's Europa Flyby Mission Moves into Design Phase". NASA. Retrieved 2017-02-22.
  29. ↑ Pappalardo, Robert T.; Vance, S.; Bagenal, F.; Bills, B.G.; Blaney, D.L.; Blankenship, D.D.; Brinckerhoff, W.B.; Connerney, J.E.P.; 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): 740–73. PMID 23924246. doi:10.1089/ast.2013.1003. Retrieved 2013-12-14.
  30. ↑ "Europa Clipper". NASA - JPL. 2015. Retrieved 2015-02-08.
  31. 1 2 3 4 5 Kane, Van (26 May 2013). "Europa Clipper Update". Future Planetary Exploration.
  32. 1 2 A. Eremenko et al., "Europa Clipper spacecraft configuration evolution," 2014 IEEE Aerospace Conference, pp. 1–13, Big Sky, MT, March 1–8, 2014
  33. ↑ Dreier, Casey (5 September 2013). "NASA's Europa Mission Concept Rejects ASRGs – May Use Solar Panels at Jupiter Instead". The Planetary Society.
  34. ↑ Foust, Jeff (8 October 2014). "Europa Clipper Opts for Solar Power over Nuclear". Retrieved 8 February 2015.
  35. 1 2 3 Amato, Michael J.; Spidaliere, P.; Mahaffy, P. (2016). Biosignature Explorer for Europa (BEE) Probe – The Concept for Directly Searching for Life Evidence on Europa at Lower Cost and Risk (PDF). 47th Lunar and Planetary Science Conference.
  36. ↑ "NASA's Europa Mission Begins with Selection of Science Instruments". Jet Propulsion Laboratory. NASA News. 26 May 2015. Retrieved 2015-05-27.
  37. 1 2 3 "Europa Mission to Probe Magnetic Field and Chemistry". Jet Propulsion Laboratory. 27 May 2015. Retrieved 2015-05-29.
  38. ↑ Blaney, Diana L. (2010). "Europa Composition Using Visible to Short Wavelength Infrared Spectroscopy". JPL. American Astronomical Society, DPS meeting #42, #26.04; Bulletin of the American Astronomical Society, Vol. 42, p.1025.
  39. ↑ Roth, Lorenz (2014). "Transient Water Vapor at Europa’s South Pole". Science. 343 (171): 171–4. ISSN 1095-9203. PMID 24336567. doi:10.1126/science.1247051.
  40. 1 2 "Radar Techniques Used in Antarctica Will Scour Europa for Life-Supporting Environments". University of Texas Austin. 1 June 2015. Retrieved 2015-06-04.
  41. ↑ Grima, Cyril; Schroeder, Dustin; Blakenship, Donald D.; Young, Duncan A. (15 November 2014). "Planetary landing-zone reconnaissance using ice-penetrating radar data: Concept validation in Antarctica". Planetary and Space Science. 103: 191–204. Bibcode:2014P&SS..103..191G. doi:10.1016/j.pss.2014.07.018.
  42. ↑ Westlake, Joseph (2014). "Workshop on the Habitability of Icy Worlds (2014)" (PDF). Retrieved 2015-05-27.
  43. ↑ Joseph, Westlake, (2015-12-14). "The Plasma Instrument for Magnetic Sounding (PIMS): Enabling Required Plasma Measurements for the Exploration of Europa". Agu.
  44. ↑ Kempf, Sascha; et al. (May 2012). "Linear high resolution dust mass spectrometer for a mission to the Galilean satellites". Planetary and Space Science. 65 (1): 10–20. Bibcode:2012P&SS...65...10K. doi:10.1016/j.pss.2011.12.019. Retrieved 2015-05-27.
  45. ↑ "JPL Selects Europa CubeSat Proposals for Study". Jet Propulsion Laboratory. NASA. 8 October 2014. Retrieved 2015-04-17.
  46. ↑ Mini-MAGGIE: CubeSat MAGnetism and Gravity Investigation at Europa. (PDF) 2016.
  47. ↑ CubeSat Session I: Beyond LEO. 2016.
  48. ↑ Sylph – A SmallSat Probe Concept Engineered to Answer Europa's Big Question. 2016.
  49. 1 2 3 Berger, Eric (17 November 2015). "Attempt no landing there? Yeah right—we’re going to Europa". ARS Technica. pp. 1–3. Retrieved 2016-01-05.
  50. ↑ JPL moves ahead with Mars and Europa missions despite funding uncertainty. Jeff Foust. July 18, 2017.
  51. ↑
  52. ↑
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