How Dream Chaser Has Evolved Over The Last Three Decades
Around 30 years ago in 1990, a NASA spaceplane concept for crewed orbital missions was studied by NASA’s Langley Research Center. The overall goal was to create an efficient and cost effective system that would complement the Space Shuttle. However, this project would never end up being completed by NASA and has now evolved into what we know today as Dream Chaser.
This small spaceplane has quite the history despite the fact that it’s never launched. After being passed between different companies and slight design changes being made, the modern Dream Chaser spaceplane is getting close to its first ever launch. A mission facilitated by a large contract with NASA to provide cargo and disposal services for the International Space Station.
Taking a closer look back in time gives us a better perspective of this original spaceplane design, purpose, and importance within the space industry. It also highlights what exactly went wrong and what changes were made. Here I will go more in-depth into the original HL-20 plan and design, the 30 year history of this spacecraft, what to expect in the future, and more.
The Original Spaceplane
Back around the mid-1980s, there was an increasing national interest in obtaining routine access to space, and as a result, a number of Earth-to-orbit transportation systems were being studied. One, referred to as a Personnel Launch System (PLS), could utilize the HL-20 and an expendable launch system to provide manned access complementing the Space Shuttle. A full-size engineering research model of the HL-20 was constructed by the students and faculty of North Carolina State University and North Carolina A&T University for studying crew seating arrangements, habitability, equipment layout and crew ingress and egress. This engineering research model is 29 feet (8.84 m) long and provided the full-scale external and internal definition of the HL-20 for studies at the Langley Research Center.
With this unique spaceplane design, there were three main goals the agency was trying to achieve. The first had to do with increased access to space. In the era of Space Station Freedom and subsequent missions of the Space Exploration Initiative, the agency pointed out that it was imperative that the United States have an alternate means of getting people and valuable small cargo to low-Earth orbit and back should the Space Shuttle be unavailable. The next reason focused on the cost of reaching orbit. As a small vehicle designed with available technologies, the PLS was forecasted to have a low development cost. Subsystem simplification and an aircraft approach to PLS ground and flight operations can also greatly lower the costs of operating PLS. The final reason had to do with crew safety. NASA highlighted that unlike the Space Shuttle, the PLS would not have main propulsion engines or large payload bay. By removing large payload-carrying requirements from personnel delivery missions, the PLS would be a small, compact vehicle. It is then more feasible to design an abort capability to safely recover the crew during critical phases of the launch and return from orbit.
Going back even further, Predating and influencing the design of the Space Shuttle, several lifting body craft including M2-F2, M2-F3, HL-10, X-24A, and X-24B were flown by test pilots during the period 1966 – 1975. The M2-F2 and the HL-10 were proposed in the 1960s to carry 12 people to a space station following launch on a Saturn 1B. The HL-20 PLS concept has evolved from these early shapes. The “HL” designation stands for horizontal lander, and “20” reflects Langley’s long-term involvement with the lifting body concept, which included the Northrop HL-10.
NASA recognized that a lifting-body spacecraft, such as the HL-20, would have several advantages over other shapes. With higher lift characteristics during flight through the atmosphere while returning from orbit, the spacecraft can reach more land area, and the number of available landing opportunities to specific sites would be increased. Loads during entry, in terms of g-forces, would be limited to about 1.5 – 1.9. This is important when returning sick, injured, or deconditioned Space Station crew members to Earth. Wheeled runway landings would be possible, permitting simple, precision recovery at many sites around the world, including the Kennedy Space Center launch site. As far as development and Sierra Nevada Corporation taking over, years later in 2004, Dream Chaser was publicly announced. Now in late 2022, the spaceplane is very close to its first launch apart of a larger NASA contract.
Dream Chaser’s Future
Now that we know more about Dream Chaser’s history and some of the past applications and goals of this design, we can take a closer look at the modern spaceplane design and its busy upcoming schedule. 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.
Similar to past versions, the modern Dream Chaser is designed for high reusability, reducing overall cost, and providing quick turnarounds between missions. The ability to liftoff on top of multiple launch vehicles and land at a wide variety of runways makes Dream Chaser a flexible option for reliable transportation. In total there are two different variants of this spacecraft, a crewed and uncrewed option. Dream Chaser was originally designed as a crewed spaceplane, in part under NASA’s Commercial Crew Program, capable of carrying up to seven astronauts to and from the space station and other low Earth orbit (LEO) destinations. However, it’s expected to be a few years before we see any humans launching within Dream Chaser. For now, only cargo and disposal services are on the spaceplane’s agenda.
In the time since Dream Chaser was announced, there have been quite a few tests completed on the spacecraft. In February 2010, Sierra Nevada Corporation was awarded $20 million in seed money under NASA’s Commercial Crew Development (CCDev) phase 1 program for the development of the Dream Chaser. SNC completed the four planned milestones on time, including hybrid rocket test fires and the preliminary structure design. Not to mention, further initial Dream Chaser tests included the drop test of a 15% scaled version at the NASA Dryden Flight Research Center. By now we have seen multiple of these tests which help demonstrate exactly how Dream Chaser is intended to land after reentering the Earth’s atmosphere. While not all of these tests went perfectly, with one, in particular, experiencing an issue with a landing leg, they have provided some helpful data.
As Dream Chaser is only a spacecraft and not capable of leaving Earth’s atmosphere by itself, it requires a launch vehicle to get it into orbit. While the selection of this rocket for the first launch has been changed, right now it’s set to happen on United Launch Alliance’s Vulcan Centaur. Here Tenacity, the most developed Dream Chaser test article, will launch within the payload fairings of the rocket. Soon after payload separation, the wings of Tenacity will extend from their tucked position in order to fit within the fairings. At the bottom or back of Dream Chaser, connected to its access point is Shooting Star. Shooting Star adds a service for NASA to send additional critical supplies to the space station. Crews can access the Shooting Star via the aft hatch, berthing to the space station. Traveling through the Shooting Star takes them to the forward portion where they can open the hatch and gain access to the Dream Chaser. When attached to the space station, Shooting Star provides a normal cabin environment for astronauts to work, and a prime location for cargo to be removed and placed onto the station after berthing.
Unlike Dream Chaser, Shooting Star is not reusable. Once separated from Dream Chaser, the cargo module burns up safely in the Earth’s atmosphere and Dream Chaser glides gently back onto Kennedy Space Center’s runway. Since Shooting Star is disposed of on every CRS-2 mission, Sierra Space Corporation plans to maintain a production line to support all subsequent Dream Chaser missions.
Focusing back on this initial mission, it’s still scheduled to happen in the third quarter of 2023. Right now, Dream Chaser Tenacity is getting close to finishing its thermal tile application process. As for Vulcan, its first launch is only months away with the rocket expected to be transported to the launch site in only days. From here, the company will test various systems and ensure its ready for flight. Assuming this launch goes perfectly, ULA will need to prepare for its second launch, this time with Dream Chaser. While there have been quite a few delays by both companies, they are still confident in the 2023 launch timeframe. In the future, if Dream Chaser proves itself as a capable transportation option, we will likely see its use for crews to the space station, Orbital Reef, or any other commercial low Earth orbit destination.
Conclusion
Dream Chaser’s design has been in the works for multiple decades now. Going back to the mid-1980s highlights NASA’s original design intended to complement the Space Shuttle’s operations. Now in late 2022, we are less than a year away from its first launch into space. Here it will finally be put to the test and demonstrate what value it could add to today’s industry. We will have to wait and see how it progresses and the impact it has on the space industry.