Pico satellites and control over the Internet
A satellite in a stable orbit to get the earth is an expensive affair. A kilogram currently costs about 50.000 US dollars. The Technical University of Berlin and the Universitat Wurzburg have developed a solution for this problem. On the 29th. September started from the Indian spacecraft Shriharikota four pico satellites. Including the "Experimental and Educational Satellite" (BEESAT) developed in Berlin and his Wurzburg counter-piece, the experimental satellite 2, short "Uwe II". The windings bring only about 1 kilograms to the scales and have an edge length of 10 centimeters.
Already in September of last year, the Pico satellites were sent on board an Indian PSLV C14 rocket to their journey in the orbit. The student team around Dipl. Ing. Frank Baumann, the project manager for the construction of the BEESAT satellites, pursued the successful start of Berlin via video stream. "As via the Internet chat from India the information came that" Beesat was successfully separated from the rocket top, there was spontaneous applause, "Baumann said. For the first radio contact with BEESAT in Berlin, however, the team had to wait a few more times. Only about 2 hours later appeared on the screens in the spacecraft control center the first telemetry data from the satellite. "A short evaluation of the data showed very quickly that Beesat was in good condition," so farther.
Start of the rocket in India; Source: ISRO
Beesat is already the seventh satellite that the TU-Berlin pushed all. Already in 1991, Tubsat-A was successfully launched the first earth trabant. Beesat is now four months in all and Baumann hopes that he works "about a year."But it is quite imagined that Beesat reaches a much more long running time, as the last started Pico satellite" after all for three years was ready for functioning, "says Baumann.
In the development of Beesat, the team of the TU-Berlin had to produce important components of the satellite completely self. Although there were a whole series of components that are available on the open market, they did not meet the coarse requirements for Pico satellites. In particular, the position control set the team in front of rough difficulties.
"If the situation of the satellite is to be changed in orbit, so-called reducing rades worked," explores Baumann. This approximately centbuster flywheels are mounted on three axes in the satellite housing and hold it in the desired location. It functions like a bike that can stable when the raders turn, Baumann tries to describe how to describe how. Also in the test phase of Beesat before the start was demanded by the winzling a lot. "We pack in a vacuum chamber to test them," says Baumann.
The control of a satellite over the Internet
Also prof. Dr. Klaus Schilling, Lecturer for Computer Science at the University of Wurzburg knows the problems of Baumann. Because he also has a pico satellite into all with a student team. "Bring a complete satellite to a kilogram is a rough task," he says. With Uwe II, the University has already completed the second Pico satellite. However, the University of Wurzburg pursues another research focus on her work.
The goal of Wurzburg Research is the use of the internet in space. The university has this extra the new degree program for this "Aerospace computer science" created. Schilling explains that "the internet in space has a delay problem". Due to the rough distances, which had to be laid back on the way between transmitter and satellites, stowings: "The station always sends a data package to the satellite and expects it from there a confirmation that it has arrived."This confirmation fails to spat and the transmitter will send the same data package again. The goal is to control a satellite over the Internet. Currently, all satellites still had to be conducted in a control center. In the near future, however, they should then be controlled by their own computer from home.
The interior of "Uwe II". Source: Universitat Wurzburg
However, the use options for Pico satellites are still unclear. Baumann, from the TU-Berlin says: "The application is still a future music". Of course, however, that Pico satellites could be shot in blackmams of up to 100 pieces in the orbit. "There are distributed tasks in the swarm," says Baumann. After Schilling, Blacks of satellites had the advantage of a coarse overlap. A single satellite overfly overflow and again the same places on earth. However, when Schwarme was used, the times between the individual overflows could be significantly tured. According to Baumann Plan ESA and NASA together in 2012 50 Pico satellites with the same sensors. This should be made atmospharic quantities. According to Baumann, the advantage is obvious: "If one drops, it is not that bad".
However, a significant advantage in Pico satellites in contrast to more common is the significant cost savings. "Small satellites are cheaper," says Baumann. Both in production, as well as in transport in the orbit. Currently, a kilogram of payload cost in a rocket about 50.000 US dollars. "It’s about the starting costs," Baumann explains the problem. In addition, the possibility is possible to consist of the rockets of more economical:
The missiles are balanced and take more mass with anyway.
These additional weights needed the rocket to be driven away to the side after the startup. Since Pico satellites are so small, they can take the unused places in a rocket. According to Schilling, however, there was another way for Pico satellites to ask them into a secure orbit. American researchers have already experimented with cannons, "as in the novel ‘from Earth to the moon’ by Jule Verne".
However, the big problem is still the friction heat that arises when a projectile shot through the air. To compensate for this problem, the cannons could be mounted on aircraft and shot out of gross high. These were able to bring the satellites released for the shooting then closely to the airplier space and thus eliminate the problem.