There was Atlantis, Discovery, Challenger, Columbia et Endeavourand soon there will be Tenacity et Space Rider… Fourteen years after the end of the US Space Shuttle program in 2011, several similar spacecraft projects are expected to launch this year. This is the case of Space Rider of the European Space Agency (ESA), which is aiming for a first test flight in late summer or early fall, or Dream Chaser of Sierra Space, whose first mission to resupply the ISS is planned for 2025. If it is tempting to draw a parallel with the historic space shuttles, true monuments of American space, are these new vehicles really comparable to them?
« The Space Rider is very similar to space shuttles », Estimates Dante Galli, head of the program at ESA. Like the historic shuttles, “it is a space transport system: the objective is not only to put a payload into orbit but also to bring it back to Earth in a controlled manner from low orbit”. The purpose of the shuttle is to serve as a laboratory in space which will remain in orbit for approximately two months before returning to land on a landing strip, and being overhauled and reused, like the space shuttles.
Precision landing
Even if it does not have wings like the latter had, the Space Rider has in fact “the ability to make a controlled landing, thanks to a pilot parachute which allows the vehicle, autonomously, to hover on a descending trajectory more or less like an airplane, with a very reduced descent speed fundamental to guarantee the comfort of certain types of payload,” continues Dante Galli. This specifies that the European shuttle will be able to make a landing “with a precision of 150 meters, which will make it possible to land, in the future, wherever we want”.
It is for this reason that this type of space vehicle was chosen by the ESA, but not only: “This form, which we call lifting body (“supporting body” in French), integrates aerodynamic and curved surfaces which generate such lift that the vehicle is capable of maintaining flight and self-regulating upon re-entry into the earth’s atmosphere”, in addition to ” allow a more uniform temperature diffusion, and therefore a reduction in heat” during this crucial phase, specifies the program manager Space Rider.
As for the Dream Chaser from the American company Sierra Space, whose first model named Tenacity should fly this year, the similarities with the American space shuttles are obvious. The vehicle, with its wings, landing gear and cockpit-like front end, closely resembles iconic American models. And this link is clearly assumed: the Dream Chaser will land on the historic shuttle runway at the Kennedy Space Center in Cape Canaveral, Florida, although Sierra Space highlights “compatibility with commercial landing strips around the world, in order to be able to bring payloads back to Earth and unload them near the laboratories very quickly.”
From “service in orbit”
We can also compare the future missions of these new generation shuttles to those of their American predecessors. THE Dream Chaser was “selected by NASA to provide cargo delivery, return and disposal service for the International Space Station,” like the space shuttles that regularly resupplied the ISS – they even enabled its assembly in orbit – and transported astronauts there.
Space Riderwas designed to provide “service in orbit”, explains Dante Galli: experiments in microgravity, the demonstration and validation in orbit of robotic exploration, Earth observation or telecommunications systems, the inspection of satellites and their “handling or refueling, to extend their operational life”. Like the space shuttleswhich have carried out several maintenance missions of the Hubble satellite or which have served as an in-orbit laboratory on numerous occasions.
Scale models
But the Dream Chaser and the Space Rider still stand out from the old shuttles. Both vehicles are smaller than the space shuttles : where these measured 37 meters long, the Dream Chaser measures only 9. As for the Space Riderit is the size of “two minivans”, indicates the ESA.
This reduced size allows the new shuttles to be launched by conventional rockets, where the space shuttles were attached to a tank flanked by two booster thrusters. THE Space Rider will be placed under the fairing of the European Vega-C rocket and put into orbit like a conventional payload. THE Dream Chaser will be “compatible with a wide variety of rockets and will be launched folded” under a cover.
Unmanned missions
But the big difference between the two generations of space shuttles is much more important: the new vehicles are not manned. ” THE Space Rider is completely automated, while there were astronauts in the space shuttlescompares Dante Galli. This poses many fewer constraints for us in terms of designing security systems, which reduces costs. » Same for the Dream Chaseralthough a manned version is planned in the future.
It is probably their uninhabited nature which makes all the difference, while the American space shuttle program was stopped in 2011 because it was considered too dangerous after the accidents of Challenger in 1986 and Columbia in 2003, which caused the death of 14 people. The first was a “considerable trauma” for the United States, and the second “cooled the spirits”, explains Jérôme Lamy, historian and sociologist of science, researcher at the CNRS.
Not to mention the very high cost of the program, which contributed to its termination in 2011: “For manned missions, you have to secure everything, you need multiple controls to avoid possible breakdowns, redundancies… And all that costs a monstrous price », explains the researcher, who works on the history of space activities. Especially since, after thirty years of use and 135 missions, the space shuttles “had reached the end of their cycle”, while “other less expensive and more optimal competing technologies” were emerging. Disappointments to which the Dream Chaser and the Space Rider should be less likely, because they are designed with cost optimization in mind.
Source: www.20minutes.fr
