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OKEANOS

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OKEANOS
NamesOversize Kite-craft for Exploration and Astronautics in the Outer Solar system
Jupiter Trojan Asteroid Explorer
Mission typeTechnology demonstration,
Reconnaissance,
Possible sample return
OperatorJAXA
Mission duration≈12 years
>30 years for optional sample return
Spacecraft properties
Spacecraft typeSolar sail
ManufacturerISASandDLR
Launch mass1400 kg
Landing mass≈100 kg
Payload massSpacecraft: 30 kg
Lander: 20 kg[1]
DimensionsSail/solar panel:
40×40 m (1600 m2)[2]
Lander: 65 × 40 cm[1]
PowerMax: 5 kW at Jupiter[2]
Start of mission
Launch date2026
RocketH-IIAorH3[1]
Launch siteTanegashima Space Center
ContractorMitsubishi Heavy Industries
Jupiter Trojanlander
Landing date2039[2]
Main telescope
WavelengthsInfrared
Transponders
BandX-band
Capacity16 Kbps[3]
Large Mission Class

OKEANOS(Oversize Kite-craft for Exploration and Astronautics in the Outer Solar system) was a proposed mission concept toTrojan asteroids,which share Jupiter's orbit, using a hybridsolar sailfor propulsion; the sail was planned to be covered with thinsolar panelsto power anion engine.In situanalysis of the collected samples would have been performed by either direct contact or using a lander carrying a high-resolution mass spectrometer. A sample-return toEarthwas an option under study.[4]

OKEANOS was a finalist for Japan'sInstitute of Space and Astronautical Science(ISAS)'2nd Large Mission Class to be launched in 2026,[2][5][6]and possibly return Trojan asteroid samples to Earth in the 2050s.[6][7]The winning mission wasLiteBIRD.

Overview[edit]

The OKEANOS mission was a concept first proposed in 2010 to fly together with theJupiter Magnetospheric Orbiter(JMO) as part of the cancelledEuropa Jupiter System Mission – Laplace.[8]

In its latest formulation, the OKEANOS mission andLiteBIRDwere the two finalists of Japan's Large Mission Class by theMinistry of Education, Culture, Sports, Science and Technology.LiteBIRD, acosmic microwave backgroundastronomy telescope, was selected.[9]

Analyzing the composition of theJupiter Trojansmay help scientists understand how theSolar Systemwas formed. It would also help determine which of the competing hypotheses is right:[10]remnantplanetesimalsduring the formation of Jupiter, or fossils of building blocks of Jupiter, or capturedtrans-Neptunian objectsby planetary migration. The latest proposal included a lander to performin situanalyses.[11][12]There were several options for this mission, and the most ambitious one proposed to retrieve and send samples to Earth for extensive investigations.[13]Had it been selected in April 2019 for development, the spacecraft would have launched in 2026,[2]and may had offered some synergy withLucyspacecraftthat will flyby multiple Jupiter Trojans in 2027.[14]

Spacecraft[edit]

The spacecraft was projected to have a mass of about 1,285 kg (2,833 lb) including a possible lander[3]and would have been equipped with solar electricion engines.[5]The 1600 m2sail would have had a dual purpose of solar sail propulsion and solar panel for power generation. If a lander had been included, its mass would have been no greater than 100 kg. The lander would have collected and analyzed samples from the asteroid. A more complex suggested concept would have had the lander take off again, rendezvous with the mothership and transfer the samples for their transport to Earth.

Solar sail and solar panels[edit]

The unique proposed sail was a hybrid that would have provided both photon propulsion and electric power. JAXA referred to the system as a Solar Power Sail.[3][15]The sail would have been made of a 10 μm-thickpolyimidefilm measuring 40 × 40 meters (1600 m2),[2]covered with 30,000 solar panels 25 μm thick, capable of generating up to 5 kW at the distance ofJupiter,5.2Astronomical Unitsfrom theSun.[6][7][10]The main spacecraft would have been located at the center of the sail, equipped with a solar-electricion enginefor maneuvering and propulsion, especially for a possible sample-return trip to Earth.[4][6][7]

The spacecraft would have used solar sail technology initially developed for the successfulIKAROS(Interplanetary Kite-craft Accelerated by Radiation of the Sun) that launched in 2010, whose solar sail was 14 m × 14 m in size.[6][15]As with the IKAROS, the solar angle of the sail would have been changed by dynamically controlling the reflectivity ofliquid crystal displays(LCD) on the outer edge of the sail so that the sunlight pressure would produce torque to change its orientation.[16]

Ion engine[edit]

Theion engineintended for the mission was called μ10 HIsp. It was planned to have a specific impulse of 10,000 seconds, power of 2.5 kW, and a maximum thrust magnitude of 27 mN for each of the four engines.[17][18]The electric engine system would have been an improved version of the engine from theHayabusamission, used for maneuvering, and especially for an optional sample-return trip to Earth.[15][18]A study indicated the need for 191 kg ofxenonpropellant if it had been decided to bring a sample back to Earth.[18]

Lander[edit]

Lander
 Parameter/units[1]

[19]

Mass ≤ 100 kg (220 lb)
Dimensions Cylindrical: 65 cm diameter
40 cm height
Power Non-rechargeable battery
Instruments
(≤ 20 kg)
Sampling Pneumatic
Depth: ≤1 m

The mission concept considered several scenarios, targets, and architectures. The most ambitious scenario contemplatedin situanalysis and a sample-return using a lander. This lander concept was a collaboration among theGerman Aerospace Center(DLR) and Japan'sJAXA,starting in 2014.[3]The spacecraft would have deployed a 100 kg lander[4][1]on the surface of a 20–30 km Trojan asteroid to analyze its subsurface volatile constituents, such as water ice, using a 1-meter pneumatic drill powered by pressurized nitrogen gas. Some subsurface samples would have been transferred to the on boardmass spectrometerfor volatile analysis.[4]The lander's scientific payload mass, including the sampling system, would not have exceeded 20 kg. The lander would have been powered by batteries and was planned to perform an autonomous descent, landing, sampling and analysis.[3]Some samples were to be heated up to 1000 °C for pyrolysis for isotopic analysis. The conceptual payload for the lander would have included a panoramic camera (visible and infrared), an infrared microscope, aRaman spectrometer,amagnetometer,and a thermal radiometer.[20]The lander would have operated for about 20 hours using battery power.[1]

If a sample-return was to be performed, the lander would have taken off then,rendezvousand deliver the surface and subsurface samples to the mothership hovering above (at 50 km) for subsequent delivery to Earth within a reentry capsule.[5][3]The lander would have been discarded after the sample transfer.

Conceptual scientific payload[edit]

On the lander
[1]
On the spacecraft
Attached to the sail
[2]

GAP-2 and EXZIT were instruments for astronomical observations, and were not intended to be used for studying Trojan asteroids. The two would have conducted opportunistic surveys, taking advantage of the mission's trajectory. GAP-2 would have made it possible to locate the position ofGamma-ray burstswith high precision by pairing it with terrestrial observatories. EXZIT, aszodiacal lightgets significantly weak beyond the asteroid belt, would have enabled the telescope to observe thecosmic infrared background.MGF-2 was a possible a successor of the MGF instrument on board theArasesatellite, and ALADDIN-2, GAP-2 were possible successors of the respective instruments onboardIKAROS.

See also[edit]

References[edit]

  1. ^abcdefgSCIENCE AND EXPLORATION IN THE SOLAR POWER SAIL OKEANOS MISSION TO A JUPITER TROJAN ASTEROIDT. Okada, T. Iwata, J. Matsumoto, T. Chujo, Y. Kebukawa, J. Aoki, Y. Kawai, S. Yokota, Y. Saito, K. Terada, M. Toyoda, M. Ito, H. Yabuta, H. Yurimoto, C. Okamoto, S. Matsuura, K. Tsumura, D. Yonetoku, T. Mihara, A. Matsuoka, R. Nomura, H. Yano, T. Hirai, R. Nakamura, S. Ulamec, R. Jaumann, J.-P. Bibring, N. Grand, C. Szopa, E. Palomba, J. Helbert, A. Herique, M. Grott, H. U. Auster, G. Klingelhoefer, T. Saiki, H. Kato, O. Mori, J. Kawaguchi; 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083)
  2. ^abcdefghINVESTIGATION OF THE SOLAR SYSTEM DISK STRUCTURE DURING THE CRUISING PHASE OF THE SOLAR POWER SAIL MISSIONT. Iwata, T. Okada, S. Matsuura, K. Tsumura, H. Yano, T. Hirai, A. Matsuoka, R. Nomura, D. Yonetoku, T. Mihara, Y. Kebukawa, M. ito, M. Yoshikawa, J. Matsu-moto, T. Chujo, and O. Mori; 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083)
  3. ^abcdefDirect Exploration of Jupiter Trojan Asteroid using Solar Power SailArchived5 August 2020 at theWayback MachineOsamu Mori, Hideki Kato, et al. 2017
  4. ^abcdSampling Scenario for the Trojan Asteroid Exploration MissionArchived2017-12-31 at theWayback MachineJun Matsumoto, Jun Aoki, Yuske Oki, Hajime Yano; 2015
  5. ^abcTrajectory Design for Jovian Trojan Asteroid Exploration via Solar Power SailArchived31 December 2017 at theWayback MachineTakanao Saiki, Osam Mori The Institute of Space and Astronautical Science (ISAS), JAXA 2017
  6. ^abcdeJAXA Sail to Jupiter's Trojan AsteroidsPaul Gilster,Centauri Dreams15 March 2017
  7. ^abcHuge sail will power JAXA mission to Trojan asteroids and backShusuke Murai,The Japan Times21 July 2016
  8. ^Sasaki, Shio (2010)."Jupiter Magnetospheric Orbiter and Trojan Asteroid Explorer"(PDF).COSPAR.Retrieved26 August2015.
  9. ^Roadmap 2017 — Fundamental Concepts for Promoting Large Scientific Research Projects28 July 2017
  10. ^abThe Solar Power Sail Mission to Jupiter TrojansArchived2015-12-31 at theWayback MachineThe 10th IAA International Conference on Low-Cost Planetary Missions 19 June 2013
  11. ^Okada, Tatsuaki; Matsuoka, Ayako; Ulamec, Stephan; Helbert, Jorn; Herique, M. Alain; Palomba, Ernesto; Jaumann, Ralf; Grott, Matthias; Mori, Osamu; Yonetoku, Daisuke (2018)."OKEANOS - Jupiter Trojan Asteroid Rendezvous and Landing Mission using the Solar Power Sail".42nd Cospar Scientific Assembly.42.Bibcode:2018cosp...42E2497O.
  12. ^Mori, Osamu; Matsumoto, Jun; Chujo, Toshihiro; Kato, Hideki; Saiki, Takanao; Kawaguchi, Junichiro; Kawasaki, Shigeo; Okada, Tatsuaki; Iwata, Takahiro; Takao, Yuki (2018)."System Designing of Solar Power Sail-craft for Jupiter Trojan Asteroid Exploration".Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan.16(4): 328–333.Bibcode:2018JSAST..16..328M.doi:10.2322/tastj.16.328.S2CID115434656.
  13. ^Okada, Tatsuaki; Kebukawa, Yoko; Aoki, Jun; Matsumoto, Jun; Yano, Hajime; Iwata, Takahiro; Mori, Osamu; Bibring, Jean-Pierre; Ulamec, Stephan; Jaumann, Ralf; Solar Power Sail Science Team (2018)."Science exploration and instrumentation of the OKEANOS mission to a Jupiter Trojan asteroid using the solar power sail".Planetary and Space Science.161:99–106.Bibcode:2018P&SS..161...99O.doi:10.1016/j.pss.2018.06.020.S2CID125367559.
  14. ^ISAS Small Body Exploration StrategyArchived12 December 2016 at theWayback MachineLunar and Planetary Laboratory The University of Arizona-JAXA Workshop (2017)
  15. ^abcIKAROS and Solar Power Sail - Craft Missions for Outer Planetary Region ExplorationArchived2017-01-26 at theWayback MachineJ. Kawaguchi (JAXA) 15 June 2015
  16. ^Liquid Crystal Device with Reflective Microstructure for Attitude ControlToshihiro Chujo, Hirokazu Ishida, Osamu Mori, and Junichiro Kawaguchi Aerospace Research Centraldoi:10.2514/1.A34165
  17. ^Lineup of Microwave Discharge Ion EnginesJAXA
  18. ^abcMission Analysis of Sample Return from Jovian Trojan Asteroid by Solar Power SailJun Matsumoto, Ryu Funase, et al. Trans. JSASS Aerospace Tech. Japan Vol. 12, No. ists29, pp. Pk_43-Pk_50, 2014
  19. ^Science experiments on a Jupiter Trojan asteroid on the solar powered sail mission(PDF). O. Mori, T. Okada1, et al. 47th Lunar and Planetary Science Conference (2016).
  20. ^Trojan asteroid probe(in Japanese) JAXA
  21. ^EXZIT TelescopeJAXA
  22. ^Jupiter Trojan's shallow subsurface: direct observations by radar on board OKEANOS missionAlain Herique, Pierre Beck, Patrick Michel, Wlodek Kofman, Atsushi Kumamoto, Tatsuaki Okada, Dirk Plettemeier; EPSC Abstracts Vol. 12, EPSC2018-526, 2018 European Planetary Science Congress 2018
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