In this TED-Ed lesson we discovered that the construction of a space elevator, made by a tether tens of thousands of kilometers long, could revolutionize our access to space, and almost instantly boost humanity into a new space age. Tethers have already been employed in space activities since the 1960s, when a tether of about 30 meters was deployed by a Gemini capsule. In this dig deeper section, I will briefly narrate the story of the Tethered Satellite System (TSS) deployed in two Space Shuttle missions in 1992 and 1996.

First of all, are we talking about some kind of primordial space elevators? No, these experiments were not primarily designed to elevate cargo to space, or to a higher orbit. The goal of most of these tests was to study space physics, in particular plasma physics at high altitudes. Others were engineering feasibility studies, to test whether tethered systems could work in space. A tethered satellite system is generally made of three components: a main satellite (which is elevated to orbit with conventional rocket systems), a smaller satellite, and a tether that connects the two of them. The smaller satellite is released from the main one through a release system, which can in principle be used also to retrieve it once the test is completed.

Two Space Shuttle missions carried the experiments TSS-1 and TSS-1R. These missions were part of a collaboration between NASA and the Italian Space Agency (ASI), which proposed the idea of a tethered satellite system back in the 1970s thanks to two Italian scientists: Giuseppe Colombo from the University of Padua and Mario Grossi at the Smithsonian Astrophysical Observatory in USA, now known as the Center for Astrophysics | Harvard & Smithsonian.

The first experiment, TSS-1, flew aboard the Space Shuttle Mission STS-46 with Italian astronaut Franco Malerba (among others), the first Italian citizen to fly to space. Despite technical difficulties (the tether got stuck at 256 meters, instead of the 20 km planned), the experiment uncovered many of the principles that govern tethered systems in space.

Some years later, in 1996, the replacement experiment TSS-1R flew aboard the Space Shuttle Columbia during the mission STS-75, this time with two Italian astronauts: Maurizio Cheli and Umberto Guidoni. This time, the deployment of the tether was more successful and reached 19.7 kilometers above the Space Shuttle when the cable suddenly broke due to an electrical discharge. Despite the sudden interruption of the experiment, the mission was very successful and helped in investigating several theories about plasma physics. Notably, very high electrical currents were detected along the cable, which ultimately improved our understanding of how charged particles move at high altitude.

As a final, funny note, you may want to know how these two missions were referred to by the Italian public. But “satellite al guinzaglio”, or “satellite on leash,” of course!

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