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Smart Lander for Investigating Moon

"SLIM (spacecraft)" redirects here. For other uses, see Slim (disambiguation).

Smart Lander for Investigating Moon (SLIM), dubbed "Moon Sniper", was a lunar lander mission of the Japan Aerospace Exploration Agency (JAXA). The lander's initial launch date in 2021[2][9] was postponed until 2023 due to delays in its rideshare, the X-Ray Imaging and Spectroscopy Mission (XRISM).[10] On 6 September 2023 at 23:42 UTC,[a][3] XRISM launched, and SLIM separated from it later that day.

Smart Lander for Investigating Moon
Half-scale model of SLIM in landing configuration
NamesSLIM
Moon Sniper
Mission typeLunar lander/rover
OperatorJAXA
COSPAR ID2023-137D Edit this at Wikidata
SATCAT no.57803
WebsiteOfficial website Edit this at Wikidata
Mission durationTotal:
7 months, 23 days
Surface operations:
3 months, 10 days
Spacecraft properties
ManufacturerMitsubishi Electric
Launch mass590 kg (1,300 lb)[1]
Dry mass120 kg (260 lb)[2]
Dimensions1.5 × 1.5 × 2 m (4.9 × 4.9 × 6.6 ft)[1]
Start of mission
Launch date6 September 2023 (2023-09-06) 23:42:11 UTC[3]
RocketH-IIA 202
Launch siteTanegashima, LA-Y1
ContractorMitsubishi Heavy Industries
End of mission
Declared23 August 2024, 13:40[4][5]
Last contact29 April 2024 (2024-04-30)[6]
Lunar orbiter
Orbital insertion25 December 2023 (2023-12-25) 07:51 UTC[7]
Lunar lander
Landing date19 January 2024 (2024-01-19) 15:20:00 UTC[7]
Landing sitenear Shioli crater
13°18′58″S 25°15′04″E / 13.3160°S 25.2510°E / -13.3160; 25.2510[8]

On 1 October 2023, SLIM executed its trans-lunar orbit injection burns. The lander entered lunar orbit on 25 December 2023 and landed on 19 January 2024 at 15:20 UTC, making Japan the fifth country to soft-land a spacecraft on the Moon. News reports of technical difficulties made it to Earth, saying that the lander's solar panels were not oriented to the Sun; however, on 29 January, the lander became operational after conditions shifted. It has survived three lunar nights, awakening again in April.[11][12]

SLIM's operation on the Moon was terminated at 22:40 on August 23, 2024 (JST).[4][5]

Background

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The main purpose of Japan's first lunar surface mission was to demonstrate precision lunar landing. During its descent, the lander recognized lunar craters by applying technology from facial recognition systems, and determined its current location from observation data collected by the SELENE (Kaguya) lunar orbiter mission. SLIM aimed to perform a soft landing with an accuracy range of 100 m (330 ft).[9][13][14] In comparison, the accuracy of the 1969 piloted Apollo 11 Lunar Module Eagle was an elliptic which was 20 km (12 mi) long in downrange and 5 km (3.1 mi) wide in crossrange.[2]

According to Yoshifumi Inatani, deputy director general of the JAXA Institute of Space and Astronautical Science (ISAS), succeeding in this extremely precise landing will lead to enhanced quality of space exploration.[15] The expected cost for developing this project is 18 billion yen, or US$121.5 million.[16]

History

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The proposal which later came to be known as SLIM existed in 2005, as the Small Lunar Landing Experiment Satellite (小型月着陸実験衛星).[17] On 27 December 2013, ISAS called for proposals for its next "Competitively-Chosen Medium-Sized Focused Mission", and SLIM was among the seven proposals submitted.[2] In June 2014, SLIM passed the semi-final selection along with the DESTINY+ technology demonstration mission, and in February 2015 SLIM was ultimately selected.[18] From April 2016, SLIM gained project status within JAXA.[19] In May 2016, Mitsubishi Electric (MELCO) was awarded the contract for building the spacecraft.[20]

SLIM was not the first Japanese lunar lander built for operation on the Moon's surface; on 27 May 2016 NASA announced that the OMOTENASHI (Outstanding Moon exploration Technologies demonstrated by Nano Semi-Hard Impactor) CubeSat lander jointly developed by JAXA and the University of Tokyo was to be launched as a secondary payload on Space Launch System (SLS) Artemis 1. OMOTENASHI was meant to deploy a mini lunar lander weighing 1 kg; however, on November 21, 2022, JAXA announced that attempts to communicate with the spacecraft had ceased, because the solar cells failed to generate power when facing away from the Sun.[21] They did not face the Sun again until March 2023.[22]

In 2017, funding difficulties for developing XRISM led to SLIM's launch being switched from its own dedicated Epsilon flight to a rideshare H-IIA flight.[23] The resulting cost savings will be transferred to develop other satellites that are behind schedule due to XRISM.[23]

Rovers

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External media
Images
image icon  Photo of SLIM taken from LEV-2 after landing
Video
video icon  Image of the lunar surface taken from SLIM during landing

Lunar Excursion Vehicle 1

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Lunar Excursion Vehicle 1 (LEV-1) is a lunar rover which moves by hopping. It has its own direct-to-Earth communication equipment, two wide-angle visible light cameras, and electrical components and UHF band antennas courtesy of the MINERVA and OMOTENASHI projects.[24]

Science payloads:

  • Thermometer
  • Radiation monitor
  • Inclinometer

Lunar Excursion Vehicle 2

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Lunar Excursion Vehicle 2 (LEV-2) or Sora-Q, is a tiny rover developed by JAXA in joint cooperation with the toy company Tomy, Sony, and Doshisha University.[25] The baseball-sized rover has a mass of 250 g and is equipped with two small cameras. LEV-2 extends its shape to crawl on the lunar surface using two wheels at its sides, a method of locomotion inspired by frogs and sea turtles;[26] it can "run" for approximately two hours.[25] It is the second rover of its kind to attempt operations on the lunar surface; the first was on Hakuto-R Mission 1, which crashed before it could be deployed.[27][28]

Mission

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SLIM was successfully launched together with the X-Ray Imaging and Spectroscopy Mission (XRISM) space telescope on 6 September 2023 at 23:42 UTC (7 September 08:42 Japan Standard Time)[3] planning to land near Shioli crater (13.3°S, 25.2°E) via weak stability boundary-like trajectory.[29] SLIM entered lunar orbit 25 December JST.[30]

 
The lander touched down at the Sea of Nectar (circled).

The lunar lander, nicknamed Moon Sniper for its extremely accurate landing precision within the projected 100 meters (330 ft) long landing ellipse, touched down onto the Moon on 19 January 2024 at 15:20 UTC, at the Sea of Nectar (Mare Nectaris), south of the Theophilus crater. Japan thus became the fifth nation to successfully soft land an operational spacecraft on the Moon, after the Soviet Union, United States, China, and India.[31][32]

Although SLIM landed successfully, it landed on its side with the solar panels oriented westwards facing opposite the Sun at the start of the lunar day, thereby failing to generate enough power.[33] The lander was able to operate on internal battery power for a short period of time, but was manually powered down on 19 January 2024 at 17:57 UTC (20 January 02:57 Japan Standard Time) to prevent over-discharge of the battery.[21]

The two lunar rovers, deployed while the lander was hovering just before it touched down, worked as planned, with LEV-1 communicating independently to ground stations.[34] LEV-1 conducted seven hops over 107 minutes on the lunar surface. Images autonomously taken by Sora-Q (a capability it shares with its sister rover)[35] showed the SLIM had landed at a 90-degree angle, effectively on its nose, and there had been the loss of an engine nozzle during descent and even possible damage to its Earth-oriented antenna.[36] Irrespective of wrong attitude and loss of communication with the lander, the mission is already successful given confirmation of its primary goal: landing within 100 m (330 ft) of its landing spot.[37][38][36] JAXA gave itself 60 out of 100 for the landing.[26]

After the shutdown on 19 January 2024, the mission's operators still hoped that the lander would wake up in a few days when the Sun would be correctly oriented so sunlight would hit the now askew solar panels.[34] The two rovers, LEV-1 and Sora-Q, continued to operate autonomously as planned.[35] On 25 January JAXA informed the LEV-1 rover has completed its planned operational period on the lunar surface, depleted its designated power, and in a standby state on the lunar surface. While the capability to resume activity exists contingent on solar power generation from changes in the direction of the Sun, efforts will be maintained to continue receiving signals from LEV-1.[39]

Summary of operations[6]
Lunar
day		 Start
(JST)		 Interval
(day)		 End
(JST)		 Moon phase
[b]		 Duration
(day)		 Remarks
1st Jan 20 - Jan 20 9 1 Landing
1st Jan 28 8 Jan 31 17–20 4 Wake up
2nd Feb 25 28 Mar 01 16–21 6 Wake up
3rd Mar 27 31 Mar 30 17–20 4 Wake up
4th Apr 23 27 Apr 29 14–20 7 Wake up
5th May 24 31 May 28 16–20 5 No response
6th June 21 28 June 27 14–20 7 No response

On 28 January, the lander resumed operations after being shut for a week. JAXA said it re-established contact with the lander and its solar cells were working again after a shift in lighting conditions allowed it to catch sunlight.[40] After that, SLIM was put in sleep mode for the impending harsh lunar night. SLIM was expected to operate only for one lunar daylight period, or 14 Earth days, and the on-board electronics were not designed to withstand the −120 °C (−184 °F) nighttime temperatures on the Moon.

Second lunar day

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On 25 February 2024, JAXA sent wake-up calls and found SLIM had successfully survived the night on the lunar surface while maintaining communication capabilities.

Since it was midday of the lunar day on 25 February 2024, the temperature of the communications payload was extremely high, so communication was terminated after only a short period of time. JAXA was preparing for resumed operations, once the temperature has fallen sufficiently. This feat of surviving the lunar night without a radioisotope heater unit had previously been achieved only by some landers in the Surveyor Program.[41][42]

Third lunar day

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On 27 March 2024, SLIM survived its second lunar night and woke up, sending more images back to Earth, showing "perseverance."[43] JAXA said "According to the acquired data, some temperature sensors and unused battery cells are starting to malfunction, but the majority of functions that survived the first lunar night was maintained even after the second lunar night."[44]

SLIM completed its second overnight operation in the early hours of March 30th, and went dormant again.[45]

Fourth lunar day

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On 23 April 2024, it survived its third lunar night and woke up sending more images back to Earth.[46] JAXA said on the social media platform X that SLIM’s key functions were still working despite repeated harsh cycles of temperature changes.[47]

The Agency stated that they "plan to attempt to resume operation again in mid to late May, when SLIM’s solar cells start generating electricity."[48]

Fifth lunar day

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JAXA sent commands for recovery on 24 and 25 May, when it was assumed that power had been restored, but the radio waves from SLIM could not be confirmed.[49] JAXA conducted the operation again on the night of the 27th, but there was no response from SLIM. As the sun has set around SLIM and power generation is no longer possible, this lunar day's operation has unsuccessfully ended.[50]

JAXA plans to try operating SLIM again next month when it is expected to have sufficient solar power. The power was turned off overnight, so JAXA hopes that the entire system will be reset and restarted.[51]

Animation of SLIM
 
Around the Earth
 
Around the Moon
   SLIM ·    Earth ·    Moon
SLIM landing site by Lunar Reconnaissance Orbiter Camera (LROC)
 
JAXA SLIM landing site imaged by LROC
 
Before/After animation of landing site
 
Composite image landing site showing surface reflectivity changes

See also

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Notes

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  1. ^ 7 September 08:42 Japan Standard Time
  2. ^ Days from the New Moon. '15' means the Full Moon.

References

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  1. ^ a b "小型月着陸実証機(SLIM)プロジェクト移行審査の結果について" [Regarding the results of the Smart Lander for Investigating Moon (SLIM) Project Transition Review] (PDF) (in Japanese). JAXA. 14 July 2016. Archived from the original (PDF) on 15 July 2016. Retrieved 2 September 2016.
  2. ^ a b c d "小型探査機による高精度月面着陸の技術実証（SLIM）について" (PDF) (in Japanese). 3 June 2015. Archived (PDF) from the original on 22 June 2015. Retrieved 23 June 2015.
  3. ^ a b c Justin Davenport (6 September 2023). "Japanese H-IIA launches X-ray telescope and lunar lander". NASASpaceflight.com. Archived from the original on 7 September 2023. Retrieved 7 September 2023.
  4. ^ a b "小型月着陸実証機（SLIM）の月面活動の終了" [End of lunar surface activities for the Smart Lander for Investigating Moon (SLIM)]. JAXA. 26 August 2024. Retrieved 27 August 2024.
  5. ^ a b "Conclusion of Lunar Activities of the Smart Lander for Investigating Moon (SLIM)". JAXA. 26 August 2024. Retrieved 2 October 2024.
  6. ^ a b "SLIM開発・運用の状況" [Status of SLIM Development and Operation]. JAXA. Retrieved 24 August 2024.
  7. ^ a b "JAXA | Moon Landing of the Smart Lander for Investigating Moon (SLIM)". Archived from the original on 5 December 2023. Retrieved 7 December 2023.
  8. ^ "NASA's LRO Spots Japan's Moon Lander". 26 January 2024. Archived from the original on 26 January 2024. Retrieved 27 January 2024.
  9. ^ a b Jun Hongo (12 November 2015). "Japan Plans Unmanned Moon Landing". The Wall Street Journal. Archived from the original on 3 March 2018. Retrieved 22 June 2016.
  10. ^ "Missions of Opportunity (MO) in Development – X-Ray Imaging and Spectroscopy Mission (XRISM)". GSFC. NASA. Archived from the original on 6 September 2021. Retrieved 6 September 2021.
  11. ^ Mike Wall (28 March 2024). "Still alive! Japan's SLIM moon lander survives its 2nd lunar night (photo)". Space.com. Retrieved 29 March 2024.
  12. ^ Robert Lea (24 April 2024). "Japan's SLIM moon lander defies death to survive 3rd frigid lunar night (image)". Space.com. Retrieved 24 April 2024.
  13. ^ "Small lunar-lander "SLIM" for the pinpoint landing technology demonstration" (PDF). 9 June 2015. Archived from the original (PDF) on 28 March 2017. Retrieved 23 June 2015.
  14. ^ "[PPS26-10] Introduction of SLIM, a small and pinpoint lunar lander". 30 April 2014. Archived from the original on 11 April 2023. Retrieved 22 June 2016.
  15. ^ "ＪＡＸＡはどのような構想を描いているのか…スリム計画を関係者に聞く". The Sankei Shimbun (in Japanese). 11 May 2016. Archived from the original on 4 November 2018. Retrieved 5 June 2015.
  16. ^ "日本初の月面着陸機、今年から開発スタート 「世界に先駆け高精度技術目指す". The Sankei Shimbun (in Japanese). 1 January 2016. Archived from the original on 30 June 2019. Retrieved 3 February 2016.
  17. ^ Tatsuaki Hashimoto (30 November 2005). "小型月着陸実験衛星" (PDF) (in Japanese). Archived from the original (PDF) on 5 March 2016. Retrieved 22 June 2016.
  18. ^ "深宇宙探査技術実証機 DESTINY+" (PDF) (in Japanese). 7 January 2016. Archived (PDF) from the original on 28 January 2022. Retrieved 23 June 2016.
  19. ^ "ISASニュース 2016.5 No.422" (PDF) (in Japanese). Institute of Space and Astronautical Science. 27 May 2016. Archived (PDF) from the original on 11 April 2023. Retrieved 23 June 2016.
  20. ^ "Japanese lunar lander to be built by Mitsubishi Electric". The Nikkei. 18 May 2016. Archived from the original on 10 April 2023. Retrieved 22 June 2016.
  21. ^ a b 小型月着陸実証機SLIM [@SLIM_JAXA] (22 January 2024). "After landing on 1/20 0:20 JST, power from the solar cells could not be confirmed. At a battery level of 12%, the battery was disconnected (as planned) to avoid being unable to restart for a recovery operation due to over-discharge. SLIM therefore powered down at 01/20 2:57 JST" (Tweet) – via Twitter.
  22. ^ "小型衛星を月へ打ち上げ ＪＡＸＡ・東大、着陸にも挑戦 18年に２基". The Nikkei (in Japanese). 28 May 2016. Retrieved 23 June 2016.
  23. ^ a b "小型ロケット「イプシロン」、政府が19年度の打ち上げ１機中止" [Government cancels launch of small rocket "Epsilon" in 2019]. The Nikkei (in Japanese). 27 August 2017. Archived from the original on 11 April 2023. Retrieved 4 October 2017.
  24. ^ "小型プローブ LEV (Lunar Excursion Vehicle)" (PDF). Archived (PDF) from the original on 24 September 2023. Retrieved 26 August 2023.
  25. ^ a b Daichi Hirano (7 October 2022). "Palm-Sized Lunar Excursion Vehicle 2 (LEV-2)". JAXA. Archived from the original on 3 October 2022. Retrieved 22 October 2022.
  26. ^ a b "JAXA Gives Itself 60 Out of 100 for Lunar Landing | JAPAN Forward". 23 January 2024. Archived from the original on 23 January 2024. Retrieved 27 January 2024.
  27. ^ Passant Rabie (12 December 2022). "SpaceX Launches Moon-Bound Private Japanese Lander Following Delays". Gizmodo. Archived from the original on 15 December 2022. Retrieved 15 December 2022.
  28. ^ "ispace、2022年末頃の打ち上げに向け、フライトモデル組み立ての最終工程に着手 Hakuto-Rのミッション1と2の進捗報告を実施". ispace. Archived from the original on 27 June 2023. Retrieved 29 April 2023.
  29. ^ "SLIM Project 概要説明資料" (PDF) (in Japanese). JAXA / ISAS. 25 August 2023. Archived (PDF) from the original on 25 August 2023. Retrieved 25 August 2023.
  30. ^ "JAXA | Smart Lander for Investigating Moon (SLIM) lunar orbit insertion". JAXA. Archived from the original on 26 December 2023. Retrieved 26 December 2023.
  31. ^ "15h00-16h00 GMT". CNN News. 19 January 2024. CNN International.
  32. ^ "Japan counts down to 'Moon Sniper' landing on lunar surface". Al Jazeera. 19 January 2024. Retrieved 19 January 2024.
  33. ^ Kenneth Chang; Hisako Ueno (25 January 2024). "Japan Explains How It Made an Upside-Down Moon Landing". The New York Times. Retrieved 21 February 2024.
  34. ^ a b Ian Sample (19 January 2024). "Japan's SLIM spacecraft lands on moon but struggles to generate power". The Guardian. ISSN 0261-3077. Archived from the original on 19 January 2024. Retrieved 20 January 2024.
  35. ^ a b Mari Yamaguchi (26 January 2024). "Moon lander hits target, looks to be upside-down". Archived from the original on 27 January 2024. Retrieved 27 January 2024 – via PressReader.
  36. ^ a b 小型月着陸実証機（SLIM）および小型プローブ（LEV）の月面着陸の結果・成果等 の記者会見 on YouTube
  37. ^ Andrew Jones (22 January 2024). "Japan's moon lander forced to power down but may yet be revived". SpaceNews. Retrieved 25 January 2024.
  38. ^ "SLIM Project Press Kit" (PDF). JAXA. Archived (PDF) from the original on 8 September 2023. Retrieved 25 August 2023.
  39. ^ Result and Achievements of the Lunar Excursion Vehicle (LEV-1) on board Smart Lander for Investigating Moon (SLIM)
  40. ^ Kelly Ng (29 January 2024). "Japan: Moon lander Slim comes back to life and resumes mission". BBC News. Retrieved 31 January 2024.
  41. ^ Kantaro Komiya (26 February 2024). "Japan's SLIM moon probe unexpectedly survives lunar night". Reuters.
  42. ^ Greg Brosnan (26 February 2024). "Japan Moon lander survives lunar night". BBC News. Retrieved 27 February 2024.
  43. ^ "Japan Moon probe survives second lunar night: Space agency". MoneyControl.com. 28 March 2024. Retrieved 29 March 2024.
  44. ^ Mike Wall (27 March 2024). "Still alive! Japan's SLIM moon lander survives its 2nd lunar night (photo)". Space.com.
  45. ^ Japan's Moon lander goes dormant again: JAXA, ap7am.com, 1/04/2024.
  46. ^ Leah Crane. "Japan's SLIM moon lander has shockingly survived a third lunar night". New Scientist. Retrieved 25 April 2024.
  47. ^ Japan’s moon lander wasn’t built to survive a weekslong lunar night. It’s still going after 3, AP.
  48. ^ Japan’s ‘Moon Sniper’ keeps baffling experts by waking up. It has shared images from its latest lunar ‘day’, CNN.
  49. ^ @SLIM_JAXA (27 May 2024). "The #SLIM project attempted to send commands to restore power on Friday, May 24th and Saturday, May 25th, when power was expected to be restored, but was unable to confirm any radio signals from SLIM. They plan to try again on the night of Monday, May 27th. #JAXA" (Tweet) (in Japanese) – via Twitter.
  50. ^ @SLIM_JAXA (28 May 2024). "We tried again on the night of the 27th, but there was no response from #SLIM . As the sun went down around SLIM on the night of the 27th, it was no longer possible to generate electricity, so unfortunately this month's operations will come to an end. Thank you very much for the overwhelming support you have shown since the previous day's post" (Tweet) (in Japanese) – via Twitter.
  51. ^ @SLIM_JAXA (28 May 2024). "We plan to try operating it again next month when it is expected that there will be sufficient solar power generation. The power was turned off overnight, so we hope that the whole system will be reset and restarted. #SLIM #JAXA" (Tweet) (in Japanese) – via Twitter.

Further reading

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  • JAXA | 宇宙航空研究開発機構 [JAXA: Uchūkōkūkenkyūkaihatsukikō] (19 January 2024). 小型月着陸実証機SLIM ピンポイント月着陸ライブ・記者会見 [kogata tsuki chakuriku jisshō-ki SLIM pin pointo tsuki chakuriku raibu kisha kaiken] (in Japanese). Udh6kvjZYC8 on YouTube.
  • JAXA: Japan Aerospace Exploration Agency (19 January 2024). SLIM Moon Landing Live & Press Conference. nvXLt3ET9mE on YouTube.
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