Dream Chaser Tenacity Continues To Make Progress Toward Its First Launch
Decades ago the Space Shuttle managed to become a key spacecraft responsible for increasing access to space and helping construct low Earth orbit infrastructure still in use today. While by no means the same, Dream Chaser and Sierra Space have taken note of the Shuttle and tried to improve on the downfalls of the past spaceplane.
Right now, Dream Chaser Tenacity is getting closer to its first ever launch scheduled in the third quarter of 2023. Just a few days ago, we learned more about this next generation spacecraft’s propulsion system, and exactly how it plans to maneuver once in space. Not to mention more details regarding its main engines and the launch process.
All of which an important aspect of the Dream Chaser design and what it hopes to accomplish in the coming years. If successful, this vehicle could once again change how we access space, and provide some unique services that we haven’t seen since the Shuttle. Here I will go more in-depth into the new propulsion updates, Tenacity’s current schedule and progress, what to expect in the future, and more.
Propulsion Update
Only three days ago Sierra Space tweeted saying, “We are committed to developing and implementing innovative and low-cost, in-space, upper stage, and boost propulsion systems.” Right now in a rural part of Wisconsin, Sierra Space has 28 acres featuring 4 test cells and 5 test stands for propulsion testing. Back in 2019, for the first time, the company opened the site to the public to view a test-firing of its patented VORTEX® rocket engine, showcasing next-generation technology available to NASA, the U.S. Air Force (USAF), commercial launch companies, and the Dream Chaser spacecraft itself.
SNC’s VORTEX engine technology enables the manufacturing of simpler, low-cost, lightweight, and more robust rocket engines, including upper stage engines that ignite at high altitude and boost vehicles operating in the upper regions of the atmosphere. SNC’s VORTEX upper stage engine is expected to yield tens of millions of dollars in savings for each launch. SNC is co-investing with the USAF for development of the engine for USAF needs.
Besides the main VORTEX engines, just days ago we learned more about the just as important RCS thrusters on Dream Chaser. In total, Dream Chaser will feature 26 reaction control system thrusters across the entire spaceplane. This includes 6 on the back of Shooting Star forming somewhat of a large circle, 6 on either side of the back of Dream Chaser, and 8 more at the very front of the spaceplane. In comparison, the Space Shuttle Orbiter had a lot of thrusters, which were required to control vehicle attitude in both orbital flight and during the early part of atmospheric entry, as well as carry out rendezvous and docking maneuvers in orbit. Shuttle thrusters were grouped in the nose of the vehicle and on each of the two aft Orbital Maneuvering System pods. No nozzles interrupted the heat shield on the underside of the craft; instead, the nose RCS nozzles which control positive pitch were mounted on the side of the vehicle, and were canted downward. The downward-facing negative pitch thrusters were located in the OMS pods mounted in the tail/afterbody. Altogether there were 38 primary RCS jets on the Shuttle.
As far as the thrusters application to Dream Chaser, its first mission is a perfect example. 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. The first mission will be next year when Dream Chaser Tenacity is expected to dock with the International Space Station. This process involves extreme accuracy and precision which is exactly what all of these thrusters are intended for.
Sierra Space’s VORTEX engine thrust chamber assembly confines propellant mixing and burning to the core region of a coaxial vortex flow field. Enabling dramatic cost savings through robust design margins also leads to extremely high durability, reliability, and reusability in engines that are inexpensive to manufacture and maintain. The coaxial vortex flow field is also applicable to hybrid rocket engine systems to produce fuel regression rates significantly higher than conventional hybrid configurations. This increase in fuel regression rate enables the use of a simple circular grain port, conferring significant gains in performance, reliability, and durability of hybrid systems.
Tenacity’s First Launch
Now that we know more about some of the thrusters and various propulsion on Dream Chaser, we can take a closer look at Tenacity’s progress and the upcoming mission. Right now that we know of, Sierra Space is working on two different Dream Chaser test articles that are hoping to access space in the near future. This includes Tenacity, which is the farthest ahead, and the second test article that doesn’t have a name yet that was recently revealed. The first mission is scheduled with Tenacity which should be finished with Heat Shield tile application not long from now. Dream Chaser uses thousands of thermal tiles across its body to protect against the heat of reentry. Unfortunately, these unique individual tiles take some time for installation. Over the past few months, this is what the company has been working on. However, based on current progress, Sierra Space looks to be on track for a 2023 third quarter launch.
On the other hand, United Launch Alliance, which is provided the rocket for this mission, might end up facing delays. Right now we are still waiting for the maiden flight of Vulcan, which has been pushed back quite a bit of the last couple of years. Ideally, this mission gets completed on time in the next couple of months. If not, it would most definitely delay its second mission, which Tenacity is expected to fly on. Something we will have to keep an eye on as time goes on.
One of the most complex aspects of Tenacity’s future mission has to do with propulsion. Sierra Space has been working to try and provide economical testing services for rapid development of rocket engine components and systems. Their test facilities are designed to cost-effectively test liquid rocket engines, hybrid rocket engines at thrust levels from 1lbf up to 150,000lbf. In addition, testing can be conducted for cryogenic components and instrumentation. To be specific, they highlight that diverse activities in propellants and combustion include the synthesis of new, non-toxic propellants, the study of gelled propellant combustion, and the development of new diagnostics for combustion and two-phase flows.
Synthesis work involves the development of safe, energetic hypergols, new oxidizers, and energetic binders. Several non-toxic hypergols designed to replace MMH have been developed. their work targets the atomization, vaporization, mixing, and ignition of propellant gels. Diagnostic work includes spray analysis, phosphor thermometry, and gamma densitometry measurements. Gamma is applied to measure void fraction in cryogenic and other two-phase flows relevant to many propulsion applications. All of which is expected to apply to the upcoming mission and multiple propulsive components of Dream Chaser.
Designed for high reusability, Tenacity reduces overall cost, 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. 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. Years ago, 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. The crewed version of Dream Chaser is approximately 85% common to the cargo system, limiting primary changes to windows, environmental control, and life support systems. In addition, an integral main propulsion system is available for abort capability and major orbital maneuvers. To put size in perspective, Dream Chaser is 30 feet, or 9 meters long—roughly ¼ the total length of the space shuttle orbiters—and can carry up to seven crew members.
The Dream Chaser spaceplane is trying to become 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. Using the Shooting Star service module, Dream Chaser can deliver up to 5,500 kg of pressurized and unpressurized cargo to the space station, including a host of different supplies and science experiments before returning to Earth.
Conclusion
Sierra Space is working hard to create a next generation space plane. This not only involves complex heat shield technology but also a complete propulsion system featuring main engines, RCS thrusters, and much more. With Tenacity’s first launch still scheduled to happen in the third quarter of 2023, the company is getting close to being done. We will have to wait and see how it progresses and the impact it has on the space industry.
