LOTUSat-1 — Vietnam's first radar Earth-observation satellite

LOTUSat-1 is a 580–600 kg radar imaging satellite for Vietnam, built in Japan by NEC and paid for mainly through Japanese official development assistance (ODA). Its X-band synthetic aperture radar (SAR) sees through cloud and works by day or night, which matters in a monsoon country. Planned uses are disaster response, climate-change monitoring, resource management, agriculture and environmental protection.

Origins: NEC and VNSC began talking in 2009. VNSC (founded in 2011 under the Vietnam Academy of Science and Technology, VAST) signed an agreement with Japan's Sumitomo Corporation in 2019. In April 2020 NEC announced that Sumitomo had ordered from it the full LOTUSat-1 system — satellite, launch, ground system and training — worth about 20 billion yen. It is funded by a JICA ODA loan under Japan's Special Terms for Economic Partnership (STEP), the first satellite by a Japanese firm funded this way, and NEC's first satellite system for a customer outside Japan. Vietnam adds counterpart funding.

Design: the satellite is based on Japan's ASNARO-2 radar satellite and uses NEC's NEXTAR NX-300L platform. It measures 4.0 × 4.0 × 3.9 m and has a five-year design life. It flies in a sun-synchronous orbit at about 500 km. Imaging modes are Spotlight (1 m or better), Strip Map (2 m or better) and ScanSAR (16 m or better). The ground segment at Hoa Lac Hi-Tech Park, Hanoi, has a 9 m-class antenna, a control centre and a data centre running NEC's GroundNEXTAR software. Vietnamese engineers followed design, assembly and testing in Japan.

Key dates: NEC–VNSC contract, April 2020; JAXA–NEC launch contract for the first (demonstration) flight of Epsilon S from Uchinoura, 12 Jun 2020; manufacturing phase began December 2022; VNSC campus at Hoa Lac inaugurated, 13 Mar 2026.

Setbacks: launch was first planned for 2023, then February 2025. Epsilon S second-stage motors exploded in ground tests in July 2023 and on 26 Nov 2024, and the launch was postponed with no new date. In March 2025 Japanese partners were reported to be weighing Epsilon S or another launcher.

Status 2026: the satellite is complete and stored, the ground system is ready and operators are trained. In February 2026 JAXA said it aimed to fly Epsilon S in fiscal 2026 with an existing second-stage motor. The changed version, with a second stage close to the old Epsilon design, is called Epsilon S "Block 1". It can lift less than first planned, and some materials have been replaced because they are hard to obtain. Its first flight, Epsilon No. 7, is targeted before the end of March 2027. Vietnam asked for delivery to contract quality at no extra cost (May 2026). In September 2026 VNSC's director general, Dr Vu Dinh Lam, named bringing LOTUSat-1 into operation as a priority. No new launch date was published in October or early November 2026.

Next: Epsilon S return to flight, then launch of LOTUSat-1 in 2027. A JICA training programme on satellite operations was planned for June 2026, and a three-year JICA project on satellite data for disaster and climate response is planned from March 2027. A second satellite, LOTUSat-2, is planned to be built in Vietnam; no date has been published.

Milestone path

1. 2019 (year only)

   VNSC–Sumitomo agreement signed

   Achieved

   The Vietnam National Space Center (VNSC) signed an agreement with Japan's Sumitomo Corporation for a radar Earth-observation satellite.

   Why it matters: The start of Vietnam's first radar satellite project.

2. 23 April 2020

   NEC wins full system order

   Achieved

   NEC announced that Sumitomo had ordered the full LOTUSat-1 system (satellite, launch, ground system, training), worth about 20 billion yen and funded by a JICA STEP loan.

   Why it matters: NEC's first satellite system for a customer outside Japan.

3. 12 June 2020

   Epsilon S launch contract

   Achieved

   JAXA and NEC agreed that LOTUSat-1 would fly on the first, demonstration flight of Epsilon S from Uchinoura.

   Why it matters: Tied the satellite's launch to a new, untested rocket.

4. July 2023 and 26 November 2024

   Epsilon S motor explosions delay launch

   Latest

   The Epsilon S second-stage motor exploded in ground tests in July 2023 and November 2024; the planned February 2025 launch was postponed with no new date.

   Why it matters: The main cause of the delay; the satellite itself was ready.

Milestone path

1. March 2025 (reported 10 March)

   Satellite complete and stored

   Achieved

   The 580–600 kg satellite was reported complete, with its ground system at Hoa Lac ready and partners weighing Epsilon S or another launcher.

   Why it matters: Vietnam has a finished radar satellite waiting on a launcher.

2. 4 February 2026

   JAXA sets fiscal 2026 target

   Achieved

   JAXA said it aimed to fly Epsilon S in fiscal 2026 with a second stage close to the old Epsilon design, now called "Block 1", which lifts less than first planned.

   Why it matters: Watch whether Block 1 can still carry LOTUSat-1 to its planned orbit.

3. 13 March 2026

   Hoa Lac space centre inaugurated

   Achieved

   VNSC's nine-hectare campus at Hoa Lac Hi-Tech Park, costing more than VND 7 trillion and ODA-funded, was inaugurated; it hosts the LOTUSat-1 ground system.

   Why it matters: Gives Vietnam its own control and data centre for radar imagery.

4. 2 May 2026

   Revised data-sharing agreement with JAXA

   Latest

   VNSC and JAXA exchanged a revised satellite data-sharing agreement in Hanoi, witnessed by both prime ministers; Japan aimed for a 2027 launch.

   Why it matters: Keeps the project at head-of-government level despite the delays.

Milestone path

1. 23 July 2026

   Second-stage motor test as planned

   Latest

   JAXA fired the Block 1 second-stage motor for just over two minutes at Tanegashima, as planned.

   Why it matters: JAXA's project manager called it "the biggest step" towards return to flight.

2. Fiscal 2026 (by end of March 2027)

   Epsilon S Block 1 first flight

   Planned

   The first Block 1 flight, Epsilon No. 7, is targeted before the end of March 2027; no source confirms LOTUSat-1 is on it.

   What to watch: Watch for the flight date and payload, which decide LOTUSat-1's slot.

3. From March 2027 (three years)

   JICA satellite-data project

   Planned

   A three-year JICA project on using satellite data for disaster and climate response is planned from March 2027.

   What to watch: Builds local demand for radar data and image-analysis services.

4. 2027 ("late 2027" per Vietnam's prime minister; "fiscal 2027" per VnEconomy)

   LOTUSat-1 launch

   Planned

   LOTUSat-1 is to launch into a sun-synchronous orbit at about 500 km once Epsilon S has returned to flight.

   What to watch: Vietnam's first all-weather, day-and-night imaging for disaster and climate monitoring.