|Mission type||Lunar lander|
|Mission duration||2-3 weeks in lunar orbit, several days on lunar surface (planned)|
|Launch mass||590 kg|
|Dry mass||120 kg|
|Dimensions||1.5 × 1.5 × 2 m (4.9 × 4.9 × 6.6 ft)|
|Start of mission|
|Launch date||January 2022 (planned)|
|Launch site||Tanegashima Space Center|
|Contractor||Mitsubishi Heavy Industries|
Smart Lander for Investigating Moon (SLIM) is a lunar lander being developed by the Japan Aerospace Exploration Agency (JAXA). The lander will demonstrate precision landing technology. By 2017, the lander was planned to be launched in 2021, but this has been subsequently delayed to January 2022 due to delays in SLIM's rideshare mission, XRISM.
SLIM will be Japan's first lunar surface mission, and will demonstrate precise, pinpoint lunar landing. During its descent to the Moon, the lander will recognize lunar craters by applying technology from facial recognition systems, and determine its current location from utilizing observation data collected by the SELENE (Kaguya) lunar orbiter mission. SLIM aims to soft land with an accuracy range of 100 m (330 ft). In comparison, the accuracy of the Apollo 11 Eagle lunar module was an elliptic which was 20 km (12 mi) wide in downrange and 5 km (3.1 mi) wide in crossrange. According to Yoshifumi Inatani, deputy director general of the JAXA Institute of Space and Astronautical Science (ISAS), by succeeding in this extremely precise landing, it will lead to enhancing the quality of space exploration.
SLIM is planned to be launched together with the XRISM space telescope, and is to land near the Marius Hills Hole, a lunar lava tube entrance discovered by Kaguya. The expected cost for developing this project is 18 billion yen.
The SLIM team assessed in the past the inclusion of a small rover in this mission. A preliminary concept considered a rover with two inflatable wheels that would enter —or drop into— the lava tube while deploying miniature communication relay devices along the traverse. Other concepts suggested developing a miniature rover without wheels but able to "hop" along. 
The proposal which later came to be known as SLIM existed as early as back in 2005, as the Small Lunar Landing Experiment Satellite (小型月着陸実験衛星). 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. In June 2014, SLIM passed the semi-final selection along with the DESTINY technology demonstration mission, and in February 2015 SLIM was ultimately selected. From April 2016, SLIM gained project status within JAXA. In May 2016, Mitsubishi Electric (MELCO) was reportedly awarded the contract for building the spacecraft. SLIM is scheduled to be the second Japanese lunar lander to operate from 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 will be launched as a secondary payload on Space Launch System Artemis 1. OMOTENASHI will deploy a mini lunar lander weighing 1 kg.
In 2017, because of funding difficulties arising from XARM (XRISM)'s development cost, SLIM's launch was switched from a dedicated Epsilon flight to a rideshare H-IIA flight. The resulting cost savings will be transferred to develop other satellites that are behind schedule due to XRISM.
- "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" (PDF) (in Japanese). JAXA. 14 July 2016. Retrieved 2 September 2016.
- "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. Retrieved 23 June 2015.
- "Missions of Opportunity (MO) in Development – X-Ray Imaging and Spectroscopy Mission (XRISM) – Resolve". NASA. Retrieved 9 July 2019.
- "SLIMについて". SLIM homepage (in Japanese). Retrieved 23 June 2016.
... 従来の「降りやすいところに降りる」着陸ではなく、「降りたいところに降りる」着陸へ ...'[in English?]
- Hongo, Jun (12 November 2015). "Japan Plans Unmanned Moon Landing". The Wall Street Journal. Retrieved 22 June 2016.
- "Small lunar-lander "SLIM" for the pinpoint landing technology demonstration" (PDF). 9 June 2015. Retrieved 23 June 2015.
- "[PPS26-10] Introduction of SLIM, a small and pinpoint lunar lander". 30 April 2014. Retrieved 22 June 2016.
- "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. Retrieved 5 June 2015.
- Haruyama, Junichi; Sawai, Shujiro; Nakatani, Kouji (7 March 2012). "SLIMが目指す月の縦穴。縦穴探査に期待される科学" (PDF) (in Japanese). JAXA Institute of Space and Astronautical Science. Archived from the original (PDF) on 2 February 2016. Retrieved 2 January 2016.
- "ＪＡＸＡ、無人機で月着陸へ−小型探査機「ＳＬＩＭ」を１８年度に打ち上げ". Nikkan Kogyo Shimbun (in Japanese). 21 April 2015. Archived from the original on 23 April 2016. Retrieved 22 April 2015.
- "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. Retrieved 3 February 2016.
- The Tiny Rover Payload of the SLIM Mission. (PDF) JAXA repository. 2015.
- . ISAS, JAXA. page 10.
- A new mechanism of smart jumping robot for lunar or planetary satellites exploration. Kent Yoshikawa, Masatsugu Otsuki, etal. 2017 IEEE Aerospace Conference.
-  ISAS, JAXA. 2018 leaflet.
- Hashimoto, Tatsuaki; et, al. (30 November 2005). "小型月着陸実験衛星" (PDF) (in Japanese). Retrieved 22 June 2016.
- "深宇宙探査技術実証機 DESTINY+" (PDF) (in Japanese). 7 January 2016. Retrieved 23 June 2016.
- "ISASニュース 2016.5 No.422" (PDF) (in Japanese). Institute of Space and Astronautical Science. 27 May 2016. Retrieved 23 June 2016.
- "Japanese lunar lander to be built by Mitsubishi Electric". Nikkei Asian Review. 18 May 2016. Retrieved 22 June 2016.
- "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". Nikkei (in Japanese). 28 May 2016. Retrieved 23 June 2016.
- "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". Nikkei (in Japanese). 27 August 2017. Retrieved 4 October 2017.
- Official project site (in Japanese)
- JAXA SLIM page
- ISAS/JAXA SLIM page