|Nanyang Technical University|
Singapore: Singapore’s first locally-built satellite has travelled nearly 700 million kilometres, taken 8,000 photographs and completed 4,400 successful telecommands while orbiting Earth.
All this was achieved while surviving several solar storms, hazardous radiation and more than 30 near-collisions with space debris.
The X-SAT satellite will mark three years in space this Sunday, 20 April. The 105kg micro-satellite, developed by Nanyang Technological University (NTU) and DSO National Laboratories, was launched into space on 20 April 2011 on a three-year mission. It has performed beyond expectations to survive the harshness of space and is still fully operational.
The extended lifespan of X-SAT beyond its three-year mission is due to the robustness of its hardware design and its battery which has gone past 15,000 charge-and-discharge cycles. Most lithium-batteries can undergo 500 such cycles before its capacity starts to degrade.
The longevity of its batteries has allowed NTU’s mission control station to continue communicating with X-SAT, issuing instructions and commands on a daily basis.
Instead of retiring the satellite after successful completing its three-year mission, the X-SAT will continue operating to experiment with “riskier” missions, such as testing a new control algorithm and navigation approach.
Director of NTU’s Satellite Research Centre, Associate Professor Low Kay Soon, says the fully functioning X-SAT is a technological achievement which attests to the quality of NTU's engineering expertise. NTU is also the first university in Singapore to have a satellite programme for undergraduates.
“X-SAT’s report card is impressive. As Singapore’s first locally-built satellite, it has been performing admirably, exceeding our expectations over the past three years, which was its designed mission lifespan.” Prof Low said.
“This also demonstrates that our local talent, which includes NTU graduates, are on par with the rest of the world when it comes to building satellites. This also clearly shows NTU’s capability to groom highly-trained manpower for Singapore’s growing space industry.”
NTU Provost Professor Freddy Boey said X-SAT’s third anniversary in space is a major milestone for Singapore and a testament to NTU’s strengths in applied research and engineering.
“Already Singapore has two indigenous satellites in space – the X-SAT and the VELOX-PII - both proudly made in NTU. The university will continue to challenge this frontier with four more satellites to be launched this year and the next,” Prof Boey said.
“Our excellence in space technologies research and development is one of the key reasons why world-leading companies such as ST Electronics, Lockheed Martin, German Aerospace Centre DLR and Thales Alenia Space are partnering NTU to work on aerospace and space research.”
“At the same time, we continue to groom young talents under our unique undergraduate satellite research programme, where students get to design and build satellites under the guidance of our experienced faculty. This programme will help to produce a sizable pool of trained and experienced engineers ready to contribute to Singapore’s growing aerospace and space industries.”
X-SAT’s key achievements
For the past three years, X-SAT’s camera has been busy whirring away, capturing photographs, such as of the haze in Indonesia’s Riau province and in Singapore and the volcanic eruption of Mount Sinabung in February this year.
For its environmental monitoring mission, it has taken close to 8,000 photographs all over the globe for Singapore’s environmental researchers.
The photographs have also been used for constructing 3-dimension images using a photogrammetry technique, which enabled it to analyse and track urban changes and landslides.
X-SAT had completed a number of important experiments in space, which includes testing a precise global positioning system, a joint project with the German Aerospace Centre (DLR); and an NTU-designed reconfigurable Parallel Processing Unit (PPU), which allows computer processing to be reconfigured so that X-SAT will continue functioning in outer space should any of its computing processors fail. In addition, the PPU has also successfully processed images before they are sent to the ground station.
While carrying out these tasks, the mini fridge-sized satellite also had to contend with space hazards, such as near misses by derelict satellites, debris and the fluctuating temperature in space which range from -60 degrees Celsius to 100 degrees Celsius.
Other NTU satellites
In addition to X-SAT, NTU also has another satellite orbiting the earth which was launched on 21 November last year. Named the VELOX-PII, it is a pico-satellite (satellites that weigh around 1 kg) and is designed, built and tested by undergraduate students. This undergraduate satellite programme by NTU’s Satellite Research Centre, has involved top engineering undergraduates from second year and above since 2009.
This year, the university is set to launch another two student-built satellites, the 4.5kg nano-satellite (nano-satellites typically weigh between a few kilogrammes and 20 kg) named VELOX-I, and a pico-satellite (one-fifth the size of VELOX-I weighing 250 grams) which "piggybacks" on it and will separate after launch.
NTU has also embarked on building a weather satellite named the VELOX-CI, a fridge-sized 130-kg satellite which will be used for tropical weather monitoring. The VELOX-CI, which is funded by the Economic Development Board, is now on track to be completed by September next year.
The core team from the X-SAT programme is also working on Singapore’s first commercial remote sensing satellite, TeLEOS-1. Both TeLEOS-1 and VELOX-CI are slated for launch in last quarter of next year.