Sierra Space’s Measures to Safeguard America’s Future Spacecraft, Dream Chaser
Dream Chaser, the innovative spaceplane developed by Sierra Space, is bringing back the capability of returning experiments and equipment from the International Space Station (ISS) through Earth’s atmosphere for a runway landing. While it shares some similarities with NASA’s Space Transportation System, also known as the space shuttle, Dream Chaser is actually based on a different design called HL-20, originally studied by NASA’s Vehicle Analysis Branch at the Langley Research Center in Virginia.
Sierra Space, in collaboration with NASA, is providing access to the build and design of the first-ever commercial spaceplane. The current iteration of Dream Chaser is called the DC-100, and the first vehicle in the fleet is named Tenacity. Unlike NASA’s space shuttle, which had approximately 24,000 individual tiles, Dream Chaser is covered with around 2,000 tiles, primarily due to its smaller size. These tiles are larger than those used by NASA, measuring approximately 10 by 10 inches compared to NASA’s 6 by 6 inch tiles.
Each tile on Dream Chaser is a unique design and differs in size, shape, thickness, and density. While they are made of a stronger material compared to NASA’s orbiters, they are still silica-based. Unlike the space shuttle, Dream Chaser does not have reinforced carbon carbon (RCC) panels to withstand higher temperatures. Instead, standard tiles on Dream Chaser can withstand up to 2,600°F (1,420°C) for multiple reentry cycles, while specialized tiles can handle even higher temperatures for single use.
The tiles on Dream Chaser serve multiple purposes. They protect the vehicle during reentry and help maintain a steady temperature for experiments and eventually humans inside the craft. They also normalize the temperature within the vehicle while in direct sunlight, which can reach temperatures as high as 250°F (120°C) during orbital daylight.
Dream Chaser’s unique design factor is its foldable wings, which not only allow for a smaller vehicle profile when docked to the ISS but also enable it to fit inside any five-meter payload fairing. The vehicle is set to launch atop United Launch Alliance’s newest vehicle, Vulcan, specifically the 542 variant.
Dream Chaser is expected to carry up to five metric tons of pressurized cargo and a half metric ton of unpressurized cargo to the ISS. That’s made possible through the attached Shooting Star cargo module, which provides a normal cabin environment for astronauts to work and will be disposed of prior to Dream Chaser’s reentry.
One of Dream Chaser’s standout features is its “down mass” capability, allowing it to bring experiments and equipment back to Earth. The vehicle can return 1.75 metric tons and land on most conventional runways, with the largest g-force experienced during reentry being only 1.5 Gs.
Sierra Space plans to re-waterproof the tiles between missions to ensure their effectiveness. Similar to the space shuttle, which had its tiles waterproofed between flights, Dream Chaser’s tiles will undergo a similar process.
Currently, Tenacity and its Shooting Star attachment will undergo testing at NASA Glenn Research Center in Ohio, including thermal vacuum testing, vibration testing, and acoustic testing. Following these tests, the vehicle will be delivered to NASA’s Kennedy Space Center in Florida for final processing prior to launch.
Dream Chaser represents a significant advancement in commercial spaceflight capabilities, providing a reliable and efficient means of returning experiments and equipment from the ISS. With its unique design features, including foldable wings and a robust thermal protection system, Dream Chaser is poised to play an important role in future space missions and contribute to the advancement of scientific research in space.
