1. Development

Following an unsuccessful bid by Sierra Nevada Corporation for its Dream Chaser spaceplane (mini-shuttle) as a candidate for NASA's Commercial Crew Program,^[1] SNC reinvented its ship as a cargo-carrying variant for resupply missions to ISS in an uncrewed capacity. In September 2014, NASA issued a Request for Proposal (RFP) for the second-round Commercial Resupply Services (CRS2). NASA received interest from five companies – Lockheed Martin, Boeing, Orbital ATK, Sierra Nevada, and SpaceX to this request.

SNC proposed the "Dream Chaser Cargo System". The cargo version of its Dream Chaser spaceplane would be mated to an expendable cargo module for increased cargo uplift and trash disposal. Returnable downmass would only be provided by Dream Chaser spaceplane itself. In January 2016, SNC was selected as co-winner of second-round Commercial Resupply Services (CRS2) funding, with six (6) formally contracted missions through 2024.^[2] NASA officials explained that selecting three companies rather than two for CRS-2 increases cargo capabilities and ensures more redundancy in the event of a contractor failure or schedule delay.^[3]

Shooting Star is that expendable cargo module. Fabricated from advanced composites by subcontractor Applied Composites, the Shooting Star has a high strength-to-weight ratio, permitting a high payload upmass capability. Following systems integration, the Shooting Star will move to NASA's Plum Brook Station in Cleveland, Ohio, for launch and space environment testing.^[4] "This expendable component adds a lot of versatility to the Dream Chaser's design and extends the vehicle's mission capabilities with safe disposal of materials that otherwise wouldn't be suitable for loading aboard the Dream Chaser for its return journey to Earth", SNC has noted. "It's got a nested cargo craft that itself autonomously dock with the ISS and take out the trash". It is also expected that the Shooting Star, paired with an attached satellite "bus", may also be able to resupply the Gateway and can also bid for Commercial Lunar Payloads Services (CLPS) missions to the Moon's surface.

Crew access the Shooting Star via the aft hatch, which berths to the space station. In order to gain access to the Dream Chaser, crew pass through Shooting Star to the forward portion where they can open the hatch into the Dream Chaser. When attached to the space station, Shooting Star provides a normal cabin environment for astronauts to work, and a location for cargo to be removed and placed onto the station after berthing. Initial CRS-2 missions will use berthing to allow better access for outsized cargo but Dream Chaser can also be designed with a docking adapter. Once all resupply cargo is unloaded, the transport vehicle can then be used for crewmembers to stow cargo for disposal.^[5] The Shooting Star transport vehicle is disposed on every Commercial Resupply-2 (CRS2) mission, a total of six (6) transport vehicles will be built to fulfill the six mission minimum requirement (NASA CRS-2 contract). Additional transport vehicles will be built for future missions, as required.

2. Design

NASA's CRS2 requirements influenced the initial design for the Shooting Star, when mated to the Dream Chaser spaceplane. In addition to delivering Pressurized and Unpressurized Cargo, the Shooting Star needed to serve as the Service Module for Dream Chaser.^[6] SNC contracted with ULA for launch services. ULA's Vulcan Centaur would launch Dream Chaser/Shooting Star within its 5.4 meter fairing. Shooting Star's Composite structure manufactured by Thales Alenia Space (formerly Advanced Composites) in San Diego, California .^[7] Conical shape was optimal for providing three critical functions:^[8]

• Room within the rocket fairing to mount unpressurized cargo
• Mechanical strength to carry Dream Chaser during ascent and orbit operations
• Conical base wide enough to support passive Common Berthing Mechanism to the space station

During CRS-2 missions, Dream Chaser maneuvers close to the International Space Station, where the Canadarm2 robotic arm grapples the spacecraft and berths it to a Common Berthing Mechanism on the Harmony module in a similar fashion to the Japanese H-II Transfer Vehicle (HTV) and the other American CRS vehicle, the Cygnus. Shooting Star does not provide return capability, but Dream Chaser provides for return of science and equipment to Earth. Unpressurized Cargo can be transported to ISS via attachment to exterior of Shooting Star. "Dream Chaser's Shooting Star can also actually become an orbital satellite itself", SNC has previously announced. "Its design allows for an inflatable module to be attached that can essentially convert it into an orbital platform with a very high payload and power capacity. Multi-purpose is the name of the game when it comes to making multi-planetary operations a viable, recurring long-term thing that we can actually accomplish, so Dream Chaser is looking like quite the high-value package if all of this comes together".

3. Dream Chaser Capabilities

As part of the Dream Chaser Launch System, the Shooting Star is mounted to the aft portion of the Dream Chaser spaceplane and serves as the Service Module with these capabilities for NASA's CRS-2 missions:

• 6 kW electrical power from solar panels and battery system
• Active thermal control, or cooling services
• Translation and rotation capability using six thrusters mounted on aft section
• Three external mounting locations for unpressurized cargo. Each location can hold 500 kg of cargo, or a single location can be used to carry 1500 kg of cargo.
• Internally, the Shooting Star provides normal cabin environment for the space station crew after berthing. After all resupply cargo is unloaded, cargo for atmospheric disposal can be loaded.

4. Unmanned Orbital Outpost

While the 4.8-meter Shooting Star is planned to be attached to the end of Dream Chaser for secondary cargo or disposable waste from the International Space Station (ISS), Sierra Nevada Corporation (SNC) previously noted that it is a highly versatile vehicle that can be used for other missions, including the Gateway. SNC has proposed the usage of Shooting Star as an Unmanned Orbital Outpost initially established in low-Earth orbit, with guidance, navigation and control "for sustained free-flight operations" to host payloads and support space assembly, microgravity experimentation, logistics, manufacturing, training, test and evaluation.^[9] On 17 July 2020, the Defense Innovation Unit (DIU) announced its contract with SNC for the Shooting Star. The DIU's mission involves the acceleration of adopted technologies to rapidly prototype and bring to the field advanced commercial solutions which address national security challenges.^[2] The DIU would use the Shooting Star as a "scalable, autonomous space station for experiments and logistics demonstrations" and providing faster use of emerging commercial technologies.^[10] It is anticipated that the Shooting Star will form "the core structure" of the Unmanned Orbital Outpost, using its versatility in providing "greater flexibility and modularity both internally and externally for orbital outpost mission requirements".