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THEOS-2 (Thailand Earth Observation System-2) / Thaichote-2

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In June 2018, the Thai government has announced it has selected Airbus to manufacture THEOS-2, an Earth observation satellite that will replace THEOS (also known as Thaichote), the country’s first Earth observation satellite launched in 2008. Thailand’s space agency GISTDA (Geo-Informatics and Space Technology Development Agency) confirmed that the deal took place on 15 June 2018, at the Mandarin Oriental in Bangkok, in the presence of Deputy Prime Minister Somkid Jatusripitak, Minister of Science and Technology Dr. Suvit Maesincee, and Airbus’ CEO Thomas Enders. 1)

The THEOS-2 project was approved by the Thai cabinet in March 2017. According to the cabinet reports last year, the Thai government will be investing a total of 7,800 million THB (approximately US$238 million) into THEOS-2, in hopes that it will reform and develop space-related industries in Thailand.

As part of the contract, a comprehensive capacity building program will involve Thai engineers in the development of an integrated geo-information system, ground segment and two Earth observation satellites: a very high-resolution and a small satellite system. The small satellite system from Airbus’ subsidiary SSTL will be assembled and tested in-country by Thai engineers to deliver technology transfer and involve local suppliers. This will be complemented by an extensive training scheme capitalizing on Airbus’ comprehensive geo-intelligence expertise, and will further develop Thailand’s geo-spatial industry. 2)

“We are very pleased to be working with Airbus to jointly develop an innovative end-to-end geo-information platform that will become a national center of excellence,” said Dr. Anond Snidvongs, Executive Director of GISTDA. “The platform will host and exploit multi-source data in an interoperable and integrated manner. The resulting insights will be key sources of information for Thai leaders and will help them deliver Actionable Intelligence Policy (AIP): tools for area-based management and decision-making.”

From the early stages of the program, GISTDA will feed its geo-information system with satellite imagery collected by the Airbus constellation of optical and radar Earth observation satellites Pleiades, SPOT, TerraSAR-X and TanDEM-X, as well as other sources of data.

An optical satellite system delivering ~1 m ground resolution imagery, THEOS-2 is based on Airbus’ innovative, flight-proven AstroBus-S satellite. Scheduled to be launched in 2020, it will secure the service continuity of THEOS-1, an Airbus-built satellite launched in 2008, which continues to deliver high quality imagery four years after its expected end of life. With the AstroBus-S satellite, Thailand is joining a small circle of nations with sovereign access to very high-resolution geostrategic information.

Communications: The TMTC communications will be via S-band. The payload downlink is in X-band with data rates of ~140 Mbit/s.




Development status

• June 20, 2022: Surrey Satellite Technology Ltd (SSTL) has shipped the THEOS-2 SmallSAT, a 100kg Earth Observation microsatellite, to the Thai Geo-Informatics and Space Technology Development Agency (GISTDA) in Sri Racha, Thailand. Manufactured in the UK under a 4 year customer training programme, the THEOS-2 SmallSAT is a one metre resolution class Earth Observation satellite with both still and video imaging capability, an AIS/ADS-B ship / aircraft identification payload, and a Thai customer developed experimental payload. The ADS-B payload is specific for the THEOS-2 SmallSAT and is based on the newly developed SSTL Software Defined Radio which is configurable in orbit, and which has been designed to complement SSTL’s range of small satellite sensors. 3)

- The occasion was marked by a visit from the Thai Ambassador to the UK His Excellency Mr. Pisanu Suvanajata, who said “I am honoured to be invited to witness the progress on THEOS-2 SmallSAT project before it is shipped to Thailand, and to learn more about the work that has been carried out by GISTDA to build the satellite in collaboration with SSTL here in the UK. This ongoing collaboration represents an advanced and strategic partnership between the two countries which will deliver significant benefits for socio and economic development, such as its applications in urban planning, change detection, infrastructure monitoring and humanitarian disaster monitoring for Thailand.”

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Figure 1: Professor Sir Martin Sweeting (Left) and His Excellency Mr. Pisanu Suvanajata (Right) with the THEOS-2 SmallSAT, May 2022 (image credit SSTL)

- Phil Brownnett, SSTL’s Managing Director, said “We are delighted to work with our customer GISTDA to extend the latest small satellite technologies to a new generation of engineers, cementing a successful relationship between SSTL and GISTDA. SSTL’s training programmes are testimony to the international co-operation at the heart of the space sector, and we look forward to continuing to support our GISTDA colleagues with launch and in-orbit operational support.”

- Dr. Pakorn Apaphant, GISTDA’s Executive Director, said “It is a big achievement for Thailand. Under THEOS-2 project, one of the aims is to enable Thai engineers to design, manufacture, integrate and test similar satellites in Thailand in the future. This has been done through a knowledge transfer training programme, from SSTL, involving 48 customer engineers from GISTDA. Such training and mentoring are taking place both in the UK at SSTL’s Guildford facility, and at GISTDA’s AIT facility in Thailand. Furthermore, SSTL has also been working with GISTDA to develop and qualify their in-country space supply chain, a key element to advance in-country capacity building and achieve sustainable development of space activities in Thailand.”

- SSTL’s training programme for GISTDA was devised to enable the Thai engineers to design, manufacture, integrate and test similar satellites in Thailand in the future and was built under a knowledge transfer training programme involving a total of 48 customer engineers from GISTDA, with the training and mentoring taking place both in the UK at SSTL’s Guildford facility, and in Thailand. SSTL has also been working with GISTDA to develop and qualify their in-country space supply chain, a key element to advance in-country capacity building and achieve sustainable development of space activities in Thailand.

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Figure 2: The THEOS-2 SmallSAT during final assembly and testing at SSTL’s cleanrooms in the UK (image credit SSTL)

- The THEOS-2 SmallSAT is based on SSTL’s CARBONITE series of earth observation spacecraft and will be operated by GISTDA from Thailand with support for early operations from SSTL.

- The THEOS-2 SmallSAT programme was delivered as part of the THEOS-2 Earth Observation Programme in collaboration with Airbus Defence and Space, who are delivering a very high resolution satellite and a comprehensive geo-intelligence system.

- The THEOS-2 SmallSAT is SSTL’s 20th Know-how Transfer customer training programme and the second collaboration with Thailand; SSTL previously trained Thai customer engineers during the 1995-1997 Thai-Paht mission.

• October 2021: THEOS-2 SmallSAT is not a typical Earth observation satellite. It is a GISTDA (Geo-Informatics and Space Technology Development Agency ) program of Thailand's Space Agency, that involves innovative technology transfer, payload designed and built by Thai engineers, and local manufacturing capacity building, including using for the first time a small satellite testing facility in Thailand. This 100-kg class microsatellite is currently being developed at Surrey Satellite Technology Ltd (SSTL), United Kingdom with a team of 22 Thai engineers involved in every process from design, analysis, development, manufacturing, integration, and test. This includes Thai engineer’s hands-on payload, which is based on Raspberry Pi and incorporates a Thai engineer’s newly designed sun sensor. 4)

THEOS-2 is a KHTT (Know-How-Technology-Transfer) program of SSTL for GISTDA, in order to achieve a sustainable growth environment in the Thai space industry. In this setup, manufacturing technology is being transferred to the Thai local suppliers, which will be part of a supply chain for the future satellite builds in Thailand. As of autumn 2021, the THEOS-2 microsatellite development is in the environmental verification campaign and is expected to be launched in Q4 2022.

The KHTT under this project is delivered through wide range of activities:

- 22 GISTDA Customer Engineers (referred to as CEs (Customer Engineers)) are embedded in the THEOS-2 SmallSAT project team with daily and unlimited access to SSTL mentors, in a one-on-one manner

- Further training in Thailand during the AIT/EVT (Assembly, Integration and Test/Equipment Verification Test) activities and operations training using a simulator

- On-the-job training and tasks using flight hardware and software

- Receiving a licence to SSTL’s technology to rebuild the spacecraft in Thailand in the future (that includes necessary documentation)

- Emphasis on in-country activities such as AIT and EVT

- Local parts procurement from Thai companies

- Designing and manufacturing a third payload for the satellite, which is a full responsibility of the Thai team.

- In September 2018, Arianespace reports it will orbit THEOS-2, the very-high-resolution Earth observation optical satellite for Thailand, under the terms of a turnkey contract between Airbus Defence and Space and GISTDA. 5)


Launch: Using a Vega or Vega C rocket, this Earth observation mission will be conducted from the Guiana Space Center in Kourou, French Guiana. A launch is expected in the first half of 2023.

Orbit: Sun-synchronous orbit, altitude of 500-550 km, LTDN (Local Time on Descending Node): 10:00-10:30 hours.




Sensor complement

• The primary payload is a ~1 m resolution imager, capable of still captures and video. The imager is a Cassegrain instrument with both a primary and secondary mirror and auto-focus mechanism. 6)

• The secondary payloads are AIS and ADS-B receivers. The secondary payloads use VHF antennas for the reception of ship and aircraft signals.

• The third payloads are a series of Raspberry Pi boards, completely designed by the customer engineers, to perform still capture, video, and AOCS experimental data.



1) Deyana Goh, ”Thailand selects Airbus for Theos-2 satellite, total budget $238 million,” Spacetech Asia, 19 June 2018, URL: http://www.spacetechasia.com/thailand-selects-airbus-for-theos-2-satellite-total-budget-238-million/

2) ”Airbus to provide an end-to-end Geo-Information System to Thailand,” Airbus, 25 June 2018, URL: https://www.airbus.com/newsroom/press-releases/en/2018/06/Airbus-to-provide-an-end-to-end-Geo-Information-System-to-Thailand.html

3) ”SSTL Ships the THEOS-2 SmallSAT to GISTDA in Thailand,” SSTL News, 20 June 2022, URL: https://www.sstl.co.uk/media-hub/latest-news/2022/sstl-ships-the-theos-2-smallsat-to-gistda-in-thailand

4) Atipat Wattanuntachai,Likhit Waranon,Kasia Clatworthy, ”Building Comprehensive Thailand Space Capacity through THEOS-2 SmallSAT,” Proceedings of the 72nd IAC (International Astronautical Congress), 25-29 October 2021, Dubai, UAE (United Arab Emirates), paper: IAC-21-B4.1.3, URL: https://iafastro.directory/iac/proceedings/IAC-21/IAC-21/B4/1/manuscripts/IAC-21,B4,1,3,x63323.pdf

5) ”Arianespace's Vega to orbit THEOS-2 for Thailand's GISTDA,” Space Daily, 13 September 2018, URL: http://www.spacedaily.com/reports/Arianespaces_Vega_to_orbit_THEOS_2_for_Thailands_GISTDA_999.html

6) Information provided by Pornthep Navakitkanok of GISTDA


The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (herb.kramer@gmx.net).

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