Why NASA Picked Dream Chaser For Future ISS Operations
Since the Space Shuttle’s final flight in 2011, NASA has embarked on a new approach to transport supplies, equipment, and science research to and from the International Space Station (ISS or Station) using private companies. With this strategy, we have seen both pros and cons with companies like SpaceX providing consistent and successful services while other companies such as Boeing are having a harder time.
Either way, this is the current state of operations for delivering both crew and cargo to and from the International Space Station. What’s most exciting is one of the newcomers expected to start making frequent trips in the coming years. Dream Chaser is a reusable spaceplane that has been in development for decades now. Despite its old age, in the last couple of years alone we have seen an increase in testing and development as its maiden launch date closes in.
With it now being 2023, its first mission to the ISS is scheduled for the third quarter of this year. However before this, the company first needs to complete the extensive process of attaching thousands of thermal tiles, and complete a host of final tests, just to name a few. Here I will go more in-depth into NASA’s decision and expectations of this spacecraft, the company’s plans for 2023, what to expect in the future, and more.
NASA’s Decision & Timeline
Dream Chaser is a relatively small spaceplane, designed for high reusability. It features many unique characteristics including the ability to liftoff on top of multiple launch vehicles and land at a wide variety of runways around the world. It features a crew and cargo variant with practically all missions within the next few years set to happen with an uncrewed spacecraft.
Back in 2018, NASA released an audit of commercial resupply services to the ISS. Here they made it clear that cargo missions are key to the successful utilization of the ISS and continued reliance on commercial operators to provide this vital service could play a major role in NASA’s future plans as it searches for cheaper and more efficient methods to explore space.
Sierra Nevada plans to use the Dream Chaser Cargo System to deliver a total upmass of 5,500 kg, which
includes a mix of up to 5,000 kg of pressurized upmass and up to 1,500 kg of unpressurized upmass to
the ISS to meet the total upmass capability. Sierra Nevada’s cargo delivery system combines the
Dream Chaser, initially designed for the commercial crew program as a reusable lifting body spacecraft
capable of landing on airport runways, and its new cargo module, a pressurized attachment to the
Dream Chaser. Downmass capabilities include 1,750 kg of return downmass in the Dream Chaser and
3,250 kg of disposal downmass inside the cargo module. The spacecraft is capable of either docking or
berthing with the ISS, but a new cargo module with ISS docking or berthing hatch is required for each
mission because they burn up during atmospheric reentry. Under NASA’s Commercial Resupply Services 2 (CRS-2) contract, Dream Chaser will provide a minimum of seven cargo service missions to and from the space station. On August 14, 2019, it was announced that all six Dream Chaser CRS-2 flights will be carried into orbit by ULA’s Vulcan launch vehicle. A rocket that also has not flown yet.
At the time of this original audit, NASA had some very real concerns. They specifically highlighted that “the development, first launch, and safe return of Dream Chaser are the greatest technical and schedule risks under the CRS-2 contract. By now in 2023, we know that many original dates were pushed back years as development and testing were not nearly fast enough.
While not ideal, progress has most definitely been ramping up and Sierra Space is closer than ever to launching this spaceplane for the first time. As of right now, there are two cargo Dream Chaser test articles under construction. The first is named Tenacity which has the most progress complete and the second does not have a name and is in the very early stages of development. Based on Tenacity’s progress and some of the updates from Sierra Space, it looks to be on schedule for its first launch in the third quarter of this year. This being said, Dream Chaser is not the only vehicle that needs to be ready for the mission to happen on time. ULA’s Vulcan has also not flown yet which will play a big role in Tenacity’s maiden flight. In just a few months Vulcan is set to lift off for the first time with a large payload from Astrobotic headed to the Moon. However, we haven’t received very many updates on this process in the last few months which suggests that it may be a bit behind schedule. Just a couple month delay could have a similar impact on Dream Chaser’s flight as well. Something we will need to keep an eye on as time goes on.
Dream Chaser’s Design
By itself, Dream Chaser can carry around 900 kilograms (2,000 pounds) of payload into low Earth orbit. As far as size, Dream Chaser is 30 feet, or 9 meters long—roughly ¼ the total length of the space shuttle orbiters. Thankfully, Sierra Space developed an addition to this spaceplane that adds more payload capacity and capabilities. Back in 2019, it was announced that an expendable Shooting Star cargo module would be part of the Dream Chaser cargo system for CRS-2 flights. The module is a 15-foot (4.6 m) long attachment to Dream Chaser that will allow the spacecraft to carry an additional 10,000 pounds (4,500 kg) of pressurized and unpressurized cargo to ISS. The module supports disposal of unwanted cargo by burning up upon re-entry.
In addition to carrying cargo, the Shooting Star module includes solar panels that supply up to 6 kW of electrical power. It also supplies active and passive thermal management; provides Dream Chaser translation & rotation capability via six mounted thrusters; and supports berthing or docking (in different configurations) to the ISS. Access from ISS to Dream Chaser will involve crew passing through Shooting Star (which supports a shirt-sleeve environment) and through a hatch that separates Shooting Star from Dream Chaser. Sierra Nevada says the module is capable of additional types of missions in LEO or to cis-lunar destinations; they have developed a free-flying variant with additional capabilities. Just a few years later, Sierra Nevada announced a contract with the Defense Innovation Unit (DIU) to use its Shooting Star expendable cargo vehicle as a possible commercial solution for a high-powered uncrewed orbital outpost.
The cargo version of the SNC Dream Chaser is called the Dream Chaser Cargo System (DCCS) which as we know will fly resupply flights to the ISS under NASA’s Commercial Resupply Services-2 program. To meet CRS-2 guidelines, the cargo Dream Chaser will have folding wings and fit within a 5 m diameter payload fairing, in contrast to the Crewed Dream Chaser, which is intended to launch without a fairing. The ability to fit into a payload fairing allows the cargo version to launch on any sufficiently capable vehicle, such as Ariane 5 as well as Atlas V. Since there are no humans aboard and instead only cargo, there is no need for an abort capacity and the spacecraft can sit within fairings.
The originally planned Dream Chaser Space System is a human-rated version designed to carry from three to seven people and cargo to orbital destinations such as the International Space Station. It would feature a built-in launch escape system and could fly autonomously if needed. Although it could use any suitable launch vehicle, it was planned to be launched on a human-rated Atlas V N12 rocket. The vehicle will be able to return from space by gliding (typically experiencing less than 1.5 g on re-entry) and landing on any airport runway that handles commercial air traffic. By now we have already seen Sierra Space making deals with different companies and airports around the world to add locations where this spaceplane can land after various missions. Its reaction control system thrusters burned ethanol-based fuel, which is not an explosively volatile material, nor toxic like hydrazine, allowing the Dream Chaser to be handled immediately after landing, unlike the Space Shuttle.
As of 2020, the Sierra Nevada Corporation says it still plans to produce a crewed version of the spacecraft within the next 5 years. The company says it “never stopped working” on the crewed version and fully intends to launch it after the cargo version, and is still committed to the crewed version as of 2021. In November 2021, Sierra Nevada Corporation reported that it received a $1.4 billion investment in Series A funding, which it will use to develop a crewed version of Dream Chaser and fly astronauts by 2025. On 25 October 2021, Blue Origin and Sierra Nevada Corporation’s Sierra Space subsidiary for commercial space activities and space tourism, released their plan for a commercial space station. The station, called Orbital Reef, is intended as a “mixed-use business park”. Sierra Nevada Corporation’s Dream Chaser was chosen as one of the commercial spacecraft to transport commercial crew to and from the space station, along with Boeing’s Starliner
Conclusion
Dream Chaser is a unique spaceplane that is very close to its maiden flight. Assuming everything goes according to plan and there are no delays from Sierra Space or ULA, we can expect to watch it lift off and dock to the ISS later this year in the third quarter. If successful, this mission will help propel the program the eventually the crewed variant. We will have to wait and see how it progresses and the impact it has on the space industry.
