The French rocket manufacturer Sirius Space and the Austrian startup Tumbleweed have signed a memorandum of understanding to send microgravity experiments into space. The collaboration was officially announced on Tuesday, September 29. Tumbleweed, which designs ready-to-use containers for microgravity experiments, will study their integration aboard the French suborbital demonstrator SIRIUS 1B. In the longer term, the two companies plan to aim for orbit with the future line of reusable launchers from the French manufacturer. Tumbleweed's main asset is a box called the Pod. Inside, the pressure and temperature are those of an ordinary room, and the Pod provides its own electricity, data recording, computing power, and measurement sensors. It is designed so that any failure inside remains contained. Researchers do not have to prove that their experiment can withstand the journey, a technical and administrative process that usually hinders access to space, and Tumbleweed handles the installation on the rocket. The company claims access ten times cheaper and five times faster. This year, Tumbleweed even launched Oasis Alpha, presented as the first commercial satellite from Austria, with four customer payloads, from protein production to advanced materials. Its successor, Oasis Beta, should be able to return them to Earth. SIRIUS 1B, the testbed for French microgravity, is intended to validate key technologies of the launcher in real flight, while offering a brief period of microgravity. According to Guillaume Brault, the technical director and co-founder of Tumbleweed, this mission will allow scientists to board their experiments "easily and quickly." The next step aims for orbit, that is, a flight fast enough to orbit the Earth instead of falling back immediately. Sirius is preparing a line of three reusable launchers, SIRIUS-1, SIRIUS-13, and SIRIUS-15, designed to fly multiple times. The two larger models combine respectively three and five first stages of the SIRIUS-1, a bit like Lego bricks, to place satellites under 1,100 kg to about 600 km altitude. It still needs to discuss possible missions, technical needs, and the schedule remain to be discussed. Sirius, founded in 2020, has twice been awarded under the France 2030 public investment plan for small launchers. Its CEO, Antoine Fourcade, stated the company wants to offer European startups "a trajectory going from first suborbital missions and microgravity tests up to orbital access." Sirius announced this month the first ignition of its STAR-1 engine, 3D-printed, in its complete configuration, and the CNES has opened the historical launch pad Diamant in Kourou to it. Tumbleweed has already partnered in June with the Gironde-based HyPrSpace. Guillaume Brault notes, however, that Sirius launchers "could perfectly meet" its ambition: "to offer rapid, regular, and simplified access to the space environment."