Salyut 1 was built in the shape of a tube, forty-seven feet (fourteen meters) long and thirteen feet (four meters) across at its widest point, and it weighed twenty-five tons. Four solar panels extended from its body like propellers, providing the station’s power. It contained a work compartment and control center, a propulsion system, sanitation facilities, and a room for scientific experiments. It was used only once by a three-man crew for twenty-four days. That crew died tragically during their descent to Earth in the Soyuz 11 spacecraft on June 30, 1971. The future Salyut space stations were built approximately in the same way, with improvements and modifications. Salyut 4 had a different distribution of solar panels and a solar telescope at 228 one end, and Salyut 6 and Salyut 7 had two docking ports instead of one. Salyut 7 was also a prototype “modular” space station, with numerous pieces that could be added on after launch to increase the station’s size and capabilities.