Tera-hertz Explorer
Mission typeScience, reconnaissance
Spacecraft properties
ManufacturerNICT & University of Tokyo
Start of mission
Launch datemid 2020s (as a secondary payload of
another flight to Mars)
RocketTo be announced
Mars lander
Landing siteIsidis Planitia[1]
terahertz sensor

The Tera-hertz Explorer (TEREX)[1] mission is a planned orbiter and lander that will be carrying a terahertz sensor to the surface of Mars to measure the oxygen isotope ratios of various molecules in the Martian atmosphere.[2] The objective of the mission is to understand the chain of chemical reactions that resupply the atmosphere with carbon dioxide.[2]

The lander, TEREX-1, was originally supposed to launch as a piggyback with another payload during the July 2020 Mars launch window,[3] but this has subsequently been delayed to 2022[1] and then to the mid 2020s.[4] As of September 2017, no official launch arrangement with a primary mission had yet been reached.[5] The spacecraft will orbit Mars for a short while before landing the instrument on the surface.[2][6] A dedicated orbiter, TEREX-2, was planned for launch in 2024. It will conduct a global survey of the Martian atmosphere and surface for water and oxygen levels.[1]

The mission is being developed by Japan's National Institute of Information and Communications Technology (NICT), and the University of Tokyo Intelligent Space Systems Laboratory (ISSL).[7] The project is based on a past proposal named FIRE (Far InfraRed Experiment), which was a sensor intended for JAXA's cancelled MELOS Mars orbiter.[7]

If successful, it will be Japan's first successful Mars spacecraft since the ill-fated Nozomi mission.


ISSL has previously developed two deep space probes: the PROCYON asteroid probe and the EQUULEUS CubeSat mission to Earth–Moon L2 Lagrangian point.[8] NICT will put into use their experience developing the SMILES (Superconducting Submillimeter-Wave Limb-Emission Sounder) instrument on board the ISS Kibo module, and SWI (Sub-millimeter Wave Instrument) on board the Jupiter Icy Moons Explorer, which the institute jointly developed with ESA and DLR (German Aerospace Center).[7] Unlike the Japanese Space Agency (JAXA), which is under the jurisdiction of the Ministry of Education, Culture, Sports, Science and Technology, NICT's parent agency is the Ministry of Internal Affairs and Communications (MIC). MIC formally approved the Tera-hertz Explorer mission in early 2017.[3]


The preliminary lander's dimensions are a 50 cm cube,[6] and may have a mass of 140 kg (310 lb) including propellant.[6] Its landing system is proposed to employ an inflatable aeroshell decelerator, and an airbag.[9]


  1. ^ a b c d Kasai, Yasuko (13 June 2018). "Tera-hertz Explorer, TEREX, Mission" (PDF). University of Tsukuba. NICT. Archived from the original (PDF) on 25 November 2018. Retrieved 30 April 2019.
  2. ^ a b c Mars Micro-Satellite for Terahertz Remote Sensing. Larsson, Richard; Kasai, Yasko; Kuroda, Takeshi; Maezawa, Hiroyuki; Manabe, Takeshi; Nishibori, Toshiyuki; Nakasuka, Shinichi; Wachi, Akifumi; Sagawa, Hideo. 19th EGU General Assembly, EGU2017, proceedings from the conference held 23–28 April 2017 in Vienna, Austria., p.18645. Published by the Smithsonian/NASA Astrophysics Data System.
  3. ^ a b Yamazaki, Keisuke (March 27, 2017). "Japan planning 2020 mission to put satellite in Martian orbit". The Asahi Shimbun. Retrieved 2017-05-13.
  4. ^ Takeshi Kuroda, Yasuko Kasai, Shinichi Nakasuka, Hiroyuki Maezawa, Takayoshi Yamada, Ryohei Takahashi: TEREX-1: A micro-satellite terahertz lander for the exploration of water/oxygen resources on Mars. 43rd COSPAR Scientific Assembly, Abstract B0.5-0006-21 (oral), id.223, January 2021.
  5. ^ "総務省、来年度から火星のテラヘルツ波を調査 酸素ある?生命いる?". Sankei Shimbun (in Japanese). 3 September 2017. Retrieved 28 December 2017.
  6. ^ a b c Japanese research team to develop microsized Mars probe. Yomiuri Shimbun, Asia News Network. 9 January 2017.
  7. ^ a b c "惑星資源探査 ⼩型テラヘルツ探査機" (PDF) (in Japanese). National Institute of Information and Communications Technology. 25 January 2017. Retrieved 2017-05-13.
  8. ^ Terazono, Junya (14 March 2017). "情報通信研究機構、東大などが2020年に火星周回衛星打ち上げを検討 朝日新聞が報道" (in Japanese). Retrieved 2017-05-13.
  9. ^ Mars Entry, Descent, and Landing by Small THz Spacecraft via Membrane Aeroshell. Akifumi Wachi, Ryohei Takahashi, Ryo Sakagami, Yuki Koshiro, Yasuko Kasai, Shinichi Nakasuka. AIAA SPACE and Astronautics Forum and Exposition, AIAA SPACE Forum, (AIAA 2017-5313). Published by the Aerospace Research Central.