Is Dream Chaser A New & Improved Space Shuttle?
It has been over a decade since we watched the final Space Shuttle launch in 2011. During its 30-year program, this spacecraft managed to launch 135 times. While by no means perfect, it provided some incredible services throughout its operation that are responsible for a lot of important space infrastructure still in use today. However, now in 2022, a new spaceplane named Dream Chaser is getting very close to its first launch.
This brings up the question of how this next generation spacecraft compares to the shuttle. In reality, these spacecraft share quite a few similarities and differences. For one, Dream Chaser features a heat shield consisting of thousands of individual thermal tiles, however, they insist that technology and a new design make it much more feasible than what was used on the shuttle. All of which are important to consider going forward if Dream Chaser wants to become a main mode of crew and cargo transportation in the future.
In the last few weeks alone Sierra Space has provided even more updates on this spaceplane and its progress toward the first launch scheduled next year in 2023. Here I will go more in-depth into Dream Chaser and how it compares to the Space Shuttle, its progress toward its first launch, what to expect in the future, and more.
Dream Chaser & The Space Shuttle
Currently, Sierra Space is working on the thermal tile application process for the first Dream Chaser test article named Tenacity. For months now we have watched progress be made on this spacecraft which is expected to launch for the first time in the third quarter of 2023.
In terms of comparing this spaceplane to the shuttle, one of the biggest differences is size. 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 LEO destinations. Dream Chaser is 30 feet, or 9 meters, long which is roughly ¼ the total length of the space shuttle orbiters, and can carry up to seven crew members. In addition, utilizing Sierra Space’s Shooting Star transfer vehicle, Dream Chaser can deliver up to 5,500 kg of pressurized and unpressurized cargo to the space station, including food, water, supplies and science experiments, and return to Earth with a gentle runway landing. The Space Shuttle on the other hand featured a payload of around 29,000 kg depending on the orbital inclination. It also featured the 18.3-m- (60-ft)-long by 4.6-m- (15-ft)- wide payload bay.
Another important comparison that relates to the size of these spacecraft has to do with heat shields and the number of tiles. One of the downfalls of the Space Shuttle had to do with its heat shield and a number of problems that came with it. In total, the Shuttle had around 24,000 individual thermal tiles across the entire spacecraft. NASA faced a significant structural design challenge in the creation of numerous unique tiles. It was necessary to design thousands of these tiles that had compound curves, interfaced with thermal barriers and hatches, and had penetrations for instrumentation and structural access. The overriding challenge was to ensure the strength integrity of the tiles had a probability of tile failure of no greater than 1/108. Not to mention, the amount of time necessary between missions to fix and replace specific individual tiles across the entire spacecraft.
All of which Sierra Space says they have factored into consideration and are working to improve on Dream Chaser. Specifically, Dream Chaser features around 2,000 thermal tiles in total across the entire spacecraft. When complete these tiles will protect Dream Chaser from temperatures that could reach upwards of 3,000°F on re-entry, while keeping the vehicle itself at only 350°F. Sierra Space highlights that their thermal tiles are both strong and lighter weight than what was used during the shuttle program. In terms of the design and color of the tiles, the white tiles reject more heat from the sun while on-orbit, which helps to keep the components within Dream Chaser cooler. In order to keep the tiles on Dream Chaser, Sierra Space’s engineers are using room temperature vulcanizing (RTV) silicone. RTV silicone is able to withstand high temperatures, making it perfect for bonding the tiles. Each tile is tested by using a mechanism that pulls on them, which ensures the bond is sufficient.
The company also points out that SNC engineers have been able to update their TPS tiles from what was used during NASA’s shuttle program with more innovation, better technology, and utilizing lessons learned. They use more modern manufacturing techniques to increase strength and reduce cost. Another difference between the tiles is Dream Chaser tiles are about 10 inches by 10 inches, while those on the shuttle were six inches by six inches. All of which working to improve from the past Space Shuttle and its design.
Upcoming First Launch
Now that we know more about how Dream Chaser compares to the Space Shuttle and some of the improvements Sierra Space has made, we can take a closer look at progress toward Tenacity’s first launch and the spacecraft itself. The most recent update on Dream Chaser came just one week ago. Specifically, on November 21st, Sierra Space tweeted saying, “We are at a turning point for our civilization, pivoting from 60 years of #space exploration to a new era of unprecedented economic activity, manufacturing & growth that will drive a new trillion-dollar industry.” Most importantly this included an image of a Dream Chaser test article with a majority of heat shield tiles installed.
As partially mentioned prior, this spacecraft is set to launch for the first time in the third quarter of 2023. Since Dream Chaser is only a spacecraft and not capable of escaping Earth’s atmosphere, it requires a dedicated launch vehicle in order to reach orbit. In this case, the initial mission is set to use United Launch Alliance’s Vulcan Centaur. This rocket’s first launch is scheduled just months away in early 2023. The launch with Dream Chaser is set to be Vulcan’s second mission. However, Sierra Space makes it clear that Dream Chaser can launch on a wide variety of launch vehicles, giving the company more options and safety nets if something were to go wrong. Due to the fact that this is an uncrewed Dream Chaser launching, it will be stowed within the rocket’s payload fairings with its wings tucked in. Once the payload fairings separate, Tenacity will extend its wings and continue on into orbit. However, in the future when the company attempts crewed launches, Dream Chaser will launch without a payload fairing to allow an abort capability if something goes wrong.
Years ago, NASA selected the Dream Chaser spaceplane to provide cargo delivery, return and disposal services for the International Space Station. Under the Commercial Resupply Services 2 (CRS-2) contract, Dream Chaser will provide a minimum of six cargo service missions to and from the space station. The vehicle is designed for high reusability, reducing overall cost and a quick turnaround between missions. Not to mention, the ability to launch on top of multiple launch vehicles and land at a wide variety of runways makes Dream Chaser a flexible option for reliable transportation. The crewed version of Dream Chaser is approximately 85% common to the cargo system and has environmental control and life support systems, windows for crew visibility, an integral main propulsion system for abort capability, and major orbital maneuvers. After leaving the space station, the Dream Chaser Cargo System also offers disposal services via the Shooting Star transport vehicle. Once separated from Dream Chaser, Shooting Star burns up safely in Earth’s atmosphere.
Shooting Star adds a service for NASA to send additional critical science, food, and cargo 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. Altogether, the Dream Chaser spaceplane is a multi-mission vehicle capable of supporting a variety of LEO needs. It can be customized for both domestic and international customers via vehicle configuration, launch site, destination, landing site, duration, and a host of other variables. Sierra Space has entered into agreements with multiple international space agencies. Together they are developing technologies, applications, and missions for Dream Chaser-based space systems. The company has also made deals with different spaceports around the globe. The idea being, in the future, when Dream Chaser is launching humans, it will have the ability to land at a vast number of airports around the world. A unique feature that could benefit Sierra Space’s future.
Conclusion
The Dream Chaser spaceplane is set to launch for the first time in less than a year from now in the third quarter of 2023. Looking back at the Space Shuttle, this new spaceplane shares quite a few similarities and differences. We will have to wait and see how it progresses and the impact it has on the space industry.