Spider robots climb to new heights
Two small robots have taken their first baby steps in space, crawling across a triangular web held in place by manoeuvring satellites. Whilst it may only have been a small step for the robots it could represent a giant leap for the development of large structures, such as antennas, that deploy themselves in space.
The Japanese rocket carrying the spider robots blasted off on 22 January, propelling the experiment into space [click to see a sequence from the launch]. The experiment consisted of three different interrelated tests. Firstly, the mother satellite deployed three daughter satellites that pulled out a 130-square metre large triangular net. Secondly, the robots began crawling across the net. Finally, the daughter satellites listened for a pilot signal from the Earth and responded in synchronization with each other, transmitting back in the direction of the pilot signal independent of their respective relative position.
The concept is known as a Furoshiki satellite, after the Japanese word for a cloth used to wrap up possessions. This experiment was achieved through collaboration between the Japanese Aerospace Exploration Agency (JAXA), the Universities of Kobe and Tokyo (Japan), the Vienna University of Technology and ESA's Advanced Concepts Team.
Data and images of the tests were beamed back to Earth for the team to analyse. Leopold Summerer from ESA's Advanced Concepts Team says, "This was a high-risk high-gain endeavour with three 'firsts' in space. And we won: from the video and the data we have already seen, the experiment was successful, even if not all systems behaved exactly as we predicted. We have good data from all parts of the experiment. Of course we expect to learn most from those parts of the experiment that behaved differently than we had expected."
A full analysis of what happened will take several months. One aspect to be analysed in more detail is the behaviour of the net during its deployment, clearly the most challenging part. Using the data recorded from the mission, the team will now plug the received data into computer models to simulate the net's deployment and to understand better what had actually happened.
It was probably an entanglement of knots that eventually stopped each of the crawling spider robots. Both robots started crawling, but one stopped after just five seconds. The other went on for about half a minute. "Our goal was to see at least one robot leaving its box and moving on the net. If both robots had worked for longer, the test would have been 200% successful. As it is, 100% successful is not bad," jokes Summerer, who goes on to say that, in the future, tiny cameras could be attached to the spider robots so that the team can see where they are going, independently of the cameras on the satellites. The final part of the test occurred when the daughter satellites, which were holding the net, received a pilot signal from the Earth. Locking onto this signal, they began transmitting a reply, perfectly synchronised with each other so that they simulated an antenna much larger than they actually were.
Based on this success and the full analysis of the test data, the Advanced Concepts Team is already preparing the next steps. One of them would be to add small antennas to the spider robots, so that they can join in the transmitting and receiving parts of the test, and have more onboard autonomy, intelligent visual systems, inter-robotic communication etc. . The 'father' of the robots, Bernhard Putz from the Institute of Handling Devices and Robotics of the Vienna University of Technology has already prepared his "robyspace junior" robots to accomodate these improvements.
The hope is that Furoshiki satellites could revolutionise satellite-based applications such as telecommunications, navigation and Earth observation using radars, by providing cost-effective very large antennas in space that can be launched on relatively small rockets.