There is a lot of space junk orbiting the Earth. Researchers in Norway believe that in the future there will be a market for its removal and have developed an entirely new type of robotic vision that will make this possible. This stimulated the interest of the European Space Agency (ESA).
SINTEF is developing a new 3D camera robust and precise enough to be the “eyes” of a planetary rover exploring the surface of Mars. However, since the ESA withdrew from its collaboration with the Russians because of the war in Ukraine, SINTEF researchers are now looking at other applications closer to Earth.
“Mars remains an interesting target for us,” says Jostein Thorstensen of SINTEF. “But right now it all seems a bit far off, so we’re looking at other opportunities. Satellite servicing and space debris removal have become very exciting areas,” he says. Thorstensen is a Senior Research Scientist in the Smart Sensors and Microsystems Department of SINTEF.
There are thousands of satellites and many of them require maintenance and repairs in order to extend their lifespan. Some just need to refuel. Increasing amounts of space debris are also becoming a major problem. Thousands of decommissioned satellites are still in orbit around the Earth.
“We are already in dialogue with the major European players in the space sector and we are happy to see that our technologies are generating interest,” says Thorstensen. “In early 2023, we plan to conduct initial testing of the camera in conjunction with these organizations,” he says.
ESA: The next Mars mission?
In September 2022, the ESA planned to send a planetary rover to Mars in collaboration with the Russian space agency Roscosmos. However, when Russia invaded Ukraine in February, ESA withdrew from the project. But ESA continues to support its ExoMars program. The rover, named Rosalind Franklin, is currently in Italy and ready to go, but it’s not yet clear how it will travel to Mars and be able to land on the planet.
Roscosmos delivered instruments for the rover and should also have provided the landing module that would safely guide the rover to the Martian surface. The plan included in the ExoMars program is for the rover to take samples and drill a borehole to a depth of two meters. The samples would then be collected on a later mission and brought back to Earth for analysis.
In 2016, ESA and Roscosmos launched a space vehicle carrying a satellite that continues to orbit Mars to this day. The satellite measures gases likely to provide indications on the existence of life on the red planet. At the same time the satellite was launched into orbit, a test landing was made using an Italian-made test module called Schiaparelli EDM. However, the landing procedure was initiated too early and the vehicle crashed at 300 km/h.
Since 1997, the United States has sent a total of five rovers to Mars. Two of them, Curiosity and Perseverance, are still active on the Martian surface. China is the only other country to have successfully landed a rover on Mars. The Zhurong vehicle arrived on the planet in May 2021.
(The Rosalind Franklin rover is named after the British chemist who discovered that the DNA molecule consists of a double helix – a discovery for which his colleagues Maurice Wilkins, Francis Crick and James Watson were later awarded the Nobel Prize.)
Environmental protection in space?
ESA strongly wishes that the legislation governing the protection of the environment also applies in space. Between 3,000 and 4,000 of the satellites sent into Earth orbit since 1957 now represent space waste. The number of satellites orbiting our planet is increasing explosively.
Since 2019, the company SpaceX, owned by Elon Musk, has launched more than 3,000 satellites into low Earth orbit, and this is just the beginning. Musk’s Starlink system consists of small, low-tech satellites. But others can be much larger and more complex, costing hundreds of millions of Norwegian kroner.
All about 3D photography
We humans have two eyes that provide us with stereoscopic vision. Each eye sees a little differently, giving us the ability to use depth vision. When an object is very close, we tend to squint to bring it into focus. This principle is applied by researchers to create 3D videos. Two cameras, each equipped with a laser, are positioned a short distance apart and project a pattern onto the object that requires imaging.
The cameras work with a resolution of 500 x 500 pixels, and each pixel is able to measure with an accuracy of 0.2 millimeters. The pattern projected onto the object by the laser creates a unique code in the pixels of both cameras. But the code will not be positioned exactly at the same place on the image.
Moving between the two cameras provides detailed information about the distance to the object. By using triangulation, combined with advanced data processing, it is possible to construct a three-dimensional image.
The school of hard knocks
A robot equipped with a camera and operating in orbit around the Earth must be robust. SINTEF’s camera system has successfully demonstrated that it is exactly that. In anticipation of the extreme conditions on Mars, the equipment was tested under harsh conditions. Thorstensen’s colleague, Runar Dahl-Hansen, explains that the camera must withstand strong shaking, high and low temperatures in a vacuum, high exposure to gamma radiation and electric fields five times stronger than a thunderbolt.
“In fact, the properties of the microscopic mirror improve after exposure,” says Dahl-Hansen. “Resistance testing has been found to induce ‘beneficial’ chemical defects and distribute them in such a way as to improve the performance of the piezoelectric material,” he said.
Facts about saving electricity with piezoelectric materials
Piezoelectric materials are able to convert electrical energy into mechanical energy, and vice versa. Their efficiency is very high. Up to 90% of energy is conserved during conversion.
SINTEF’s 3D camera is equipped with a millimeter-sized piezoelectric mirror that was developed and built at SINTEF’s MiNaLab. The mirror can be used to control and manipulate light with nanometer precision.
ESA wants more
“ESA was so pleased with the camera that it granted funding to SINTEF for a follow-up project,” says Thorstensen. “Even if the mission with the European Mars rover is now postponed due to the withdrawal of ESA from its collaboration with the Russians, it would never have been realistic to have a camera ready in such a short time,” says- he.
“We are still in a relatively early phase,” says Thorstensen. “The technology will not be ready for use in space for several years. But the interest of the main players in the space sector gives hope that in the future, SINTEF technology can play a role in space, either either on a Mars rover or on a maintenance satellite, preferably both,” he says.
Why is the 3D camera developed by SINTEF better than others when it comes to repairing satellites?
“It’s compact, consumes very little power, and delivers incredibly detailed close-up images,” says Thorstensen.
“Weight, size and power consumption are key factors when putting a robot into Earth orbit. Our system has less complex optical control electronics than other 3D cameras, which makes it potentially more robust and reliable “, he says.
What about the market potential?
“The use and need for specialized 3D cameras is increasing,” says Thorstensen.
“For example, organizations operating in fields such as industrial robotics, logistics, medicine and inspection are all interested in highly miniaturized cameras that deliver high-quality 3D data,” says Thorstensen.
Provided by SINTEF
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