A Closer Look At The Spacecraft Attached To Dream Chaser
Dream Chaser is a spaceplane with future plans to carry cargo and eventually crew to low Earth orbit destinations. After decades of development and testing, the vehicle is only a few months away from its first flight. However, when it does lift off, inside the fairings of the Vulcan rocket will be another spacecraft attached to the back of Dream Chaser.
Named Shooting Star, this extra module in addition to Tenacity, is fully complete and currently undergoing its final testing in preparation for launch. On an actual mission, it will provide Dream Chaser with power, a significant increase in payload capacity, and even disposal services at the end of the mission. Here I will go more in-depth into this module’s progress, why it’s so important, what the first Dream Chaser mission will look like, and more.
Shooting Star Testing
Only a few days ago Sierra Space tweeted saying, “Environmental testing has begun for the Shooting Star cargo module, which recently arrived at NASA’s Neil Armstrong Test Facility in Ohio. The spacecraft is undergoing comprehensive testing as it’s readied for its inaugural mission to resupply the ISS.” This included a short video highlighting the transport process.
This update is significant as it means both the Shooting Star module and Dream Chaser Tenacity have begun final testing. Specifically, in a statement the company commented, “Following the Shooting Star, the first Sierra Space Dream Chaser spaceplane has also arrived at the Neil Armstrong Test Facility. The two vehicles will be stacked in launch configuration and undergo rigorous environmental testing starting in the Mechanical Vibration Facility, subjecting them to the extreme conditions of launch vibrations on the world’s most powerful spacecraft shaker table” they said.
However, the Shooting Star module also has some tests of its own. Sierra Space pointed out that “This pivotal phase of testing aims to validate the spacecraft’s resilience to the demands of launch and the challenging conditions of space as Shooting Star is readied for its inaugural mission to the International Space Station.”
Focusing more on this spacecraft’s purpose, Shooting Star adds a service for NASA to send additional critical science, food, and cargo to the space station. Once it has arrived at the station, crews can access the Shooting Star via the aft hatch. At that point, traveling through the Shooting Star takes them to the forward portion where they can open the hatch and gain access to Dream Chaser. They highlight that “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.”
By now, astronauts have already been trained on how to operate and work with both Dream Chaser and the Shooting Star cargo module. They are familiar with the technology and should be comfortable interacting with it in just a few months time.
The company is confident that the Shooting Star cargo module, designed in tandem with Dream Chaser, is set to redefine cargo capabilities, power and propulsion systems in space. “This transformative Sierra Space technology will define the next era of space commercialization,” said Sierra Space CEO Tom Vice. “As we embark on this journey to build a platform in space to benefit life on Earth, our commitment to innovation, reliability and sustainability remains unwavering and is exemplified in our Shooting Star cargo module” he said.
In terms of capabilities, the module is a 15-foot-long (4.6 m) 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. With the addition of folding solar panels, it will also provide power during the trip. Interestingly, unlike the Dream Chaser spaceplane it’s attached to, Shooting Star is not reusable. As part of its utility, Shooting Star offers cargo disposal services for NASA. In this case, 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. The company points out that “Since Shooting Star is disposed of on every CRS-2 mission, Sierra Space Corporation will maintain a production line to support all subsequent Dream Chaser missions.”
With Dream Chaser being a reusable platform, the company will need to keep up and produce Shooting Star modules at a quick pace. Ideally, they improve this process overtime and create an excess of Shooting Star modules ensuring that Dream Chaser is not limited by this extra spacecraft.
Dream Chaser Flight Profile
As of right now, Dream Chaser is still expected to lift off for the first time somewhere between January and March of next year. This maiden flight is a demonstration mission officially named SNC Demo-1 and will be the first test of some of Dream Chaser’s different features. Due to the vehicle’s unique nature combined with the fact that it must dock with the ISS, its flight profile is somewhat action-packed.
Dream Chaser is only a spacecraft, not a launch vehicle, so it needs some help in order to reach orbit. For this maiden flight, the launch vehicle is United Launch Alliance’s brand new Vulcan Centaur. This rocket was supposed to attempt its maiden flight a long time ago but has run into a few different delays. After a few more errors and delays related to upper stage reinforcements, both the first and second stage are back on the launch site. Its first flight is set to happen in a few weeks on the 24th. In relation to Dream Chaser, the first mission is meant to happen on the second Vulcan flight which could cause some delays.
Either way, this is the current plan for Tenacity’s maiden flight. In this case, once the vehicle arrives at the site it will integrate with Vulcan. At this stage, Dream Chaser will have its wings folded in allowing it to fit within Vulcan’s fairings. As part of the CRS-2 contract with NASA, it was required that Dream Chaser fit within a 5m payload fairing. Inside these fairings, the spaceplane will be elevated by the Shooting Star service module which will also be used on this first test flight. The solar panels on Shooting Star supply up to 6 kW of electrical power. It also provides 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.
On launch day, Vulcan will undergo a series of checks to make sure everything is ready for flight. Finally, the two BE-4 engines will ignite in addition to the SRBs, and Vulcan will lift off. Not long after the rocket takes off the boosters will be expended and the main BE-4 engines will cut off. The two stages will then separate and the upper stage will ignite its two RL10C engines. The payload fairings will eventually jettison revealing Tenacity and its Shooting Star module.
At this point, the spacecraft will detach from the upper stage and then unfold its wings. Between then and berthing with the ISS, the spaceplane will use its various thrusters to position itself on the exact path. The main run initializes at 119 km below and behind the ISS. Through a carefully choreographed set of “burns,” Dream Chaser will approach and intercept the earth radius vector directly below the ISS. With built-in holds at several points along the way, Dream Chaser will gradually climb up to a capture point that is 11.5 meters below the space station’s Japanese Experiment Module. When Dream Chaser is at the capture point, the ISS crew moves the robot arm into position and grapples the spacecraft. Sierra Space commented that “This can take approximately six hours from start to finish in training simulations, and in most cases, is not problem-free.”
Once attached, crews on the ground and in the station will make sure everything looks good before they open the hatch and access the cargo. Tenacity is expected to stay docked with the ISS for around two to three months before it’s time to leave. At this point, crews onboard will load the spacecraft with any disposable items. When this is complete and the hatch is closed, Dream Chaser Tenacity will detach from the station and then separate from its Shooting Star module. Dream Chaser will then attempt one of the most difficult mission objectives during reentry. Assuming everything goes well it will make it through the atmosphere in one piece and begin descending toward the ground. Finally, Tenacity will attempt a landing on a runway to complete the first Dream Chaser CRS-2 Cargo mission.
Back in 2016, NASA announced that Dream Chaser had been awarded one of the CRS-2 contracts and committed to purchasing a minimum of six resupply missions to the ISS. If this demo mission goes well, we can expect the company to focus its attention on refurbishing Tenacity and continuing to build additional spaceplanes. Around a year ago the company revealed that it had begun working on a second test article separate to Tenacity. In the future, they will have a few of these cargo variants and eventually spaceplanes designed for humans.
Conclusion
Both Dream Chaser and Shooting Star have arrived at NASA’s test facility and have begun final mission prep. If the testing goes well, in a few weeks from now we can expect them to ship to Florida for eventual integration with the second Vulcan. We will have to wait and see how it progresses and the impact it has on the space industry.