Researchers want to investigate asteroid belt with fleet of nanosatellites
Finnish researchers at the Finnish Meteorological Institute have developed a plan to explore the asteroid belt between Mars and Jupiter by sending 50 nanosatellites there that are powered by trapping the protons in the solar wind.
The researchers want to study the estimated 1.1 to 1.9 million boulders in the asteroid belt with nanosatellites. This so-called Asteroid Touring Nanosat Fleet has to come up to 100 km from the asteroids and carry out measurements with spectrometers and 4cm telescopes. In doing so, the researchers plan to collect chemical composition data and photographs of more than 300 of the largest and most interesting boulders in the belt. After flying in the belt for more than 3 years, the probes could return to Earth, where the data can be read and examined. This means that no large antennas are required for data transfer.
The nanosatellites are powered by so-called E-sails, which are attached to the small probes. This is a technology proposed in 2006 by one of the current researchers, Pekka Janhunen. Solar wind is used for this propulsion technology. The charged particles of the solar wind, including protons, are collected by an electrically charged aluminum wire with a length of 20 kilometers.
The theory is that the wire becomes positively charged. If positively charged particles, protons, collide with the wire as part of the solar wind, the positively charged particles in the wire and the protons from the solar wind repel each other. The incoming protons then transfer their momentum, which provides the drive. The wire revolves around a central point, and by changing its position relative to the sun, the nanosatellite can control the degree of propulsion and direction.
The idea is that a 5-kilogram nanosatellite with a 20-kilometer wire achieves an acceleration of 1 mm/s²; eventually that leads to a significant speed that could reach the asteroid belt in just over three years. With this technology, spacecraft could theoretically reach the heliopause, the extreme limit of our solar system, in ten years. The Voyager 1 spacecraft reached this area in 2012, 35 years after its launch. This theory of an E-sail is currently being tested, including by NASA, which has developed the HERTS concept based on Janhunen’s theory.
According to Janhunen, asteroids are very diverse and so far we have only been able to view a small number of them from a short distance. More research is needed to learn more about asteroids, he says. Janhunen believes that using small spacecraft, such as the proposed nanosatellites, is the only financially viable way to study a large number of asteroids. The Asteroid Touring Nanosat Fleet should cost a total of 60 million euros.
The researchers presented their study on Tuesday in Riga, during the European Planetary Science Congress. The paper is published under the title Asteroid touring nanosat fleet with single-tether E-sails.
Animation from NASA of the HERTS concept, which consists of a number of electrically charged wires that form a circle from one point.