ARCTUS was a proposed design by Astrotech Corporation for a robotic spacecraft that would deliver cargo to the International Space Station.[1] ARCTUS was planned to be launched by an Atlas V rocket. Its pressurized cargo module would return to Earth and be recovered with a mid-air retrieval operation.
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ARCTUS will consist of three modules:
Unpressurized Cargo Module (UCM): The UCM is located on the forward end of the vehicle and provides the means to carry the external cargo. The UCM can accommodate 3 metric tons or greater (subject to launch vehicle capability) of cargo (including Orbital Replacement Units for the ISS).
Pressurized Cargo Module (PCM): Built from two Centaur aft bulkheads, the PCM can hold over 2 metric tons of internal cargo in its 18 cubic meter volume. Extended options are available providing upwards of 31 cubic meters, carrying more than 4 metric tons of pressurized cargo.
Service Module (SM): The SM is located on the aft end of vehicle and provides the interface with the launch vehicle, the Common Berthing Mechanism (CBM) ISS interface, and the spacecraft Propulsion System.
Separation mechanisms are used to allow for separation of the UCM and SM prior to reentry of the PCM.
The ARPO system is designed to take the ARCTUS vehicle from the ISS stay-out zone (approximately 3 km radius) to the ISS capture box. ARCTUS will then be grappled by the Space Station Remote Manipulator System (SSRMS) and berthed on an ISS port (nominally ISS Harmony Nadir port).
Avionics The brain of ARCTUS is derived from the flight proven XSS-11 avionics and consists of a spacecraft computer, communications and power systems, guidance and navigation system, and associated software. The majority of the avionics will be housed inside the PCM to allow for recovery and reuse for future missions.
Propulsion System A hydrazine monopropellant propulsion system provides full six degree of freedom control of ARCTUS. Eight propulsion tanks and thirty-two 9 pound rocket engine modules form the basis of the system.
Guidance, Navigation and Control (GN&C) The ARCTUS GN&C system is based on the XSS 11 avionics. The system consists of dual redundant Inertial Measurement Units (IMUs) and Global Positioning System (GPS) units, dual star trackers and associated flight software.
Payload Accommodations The ARCTUS payload accommodations are based on SPACEHAB's 20 years of experience in delivering NASA, ESA, JAXA, Russian, and commercial cargo to space.
Environmental Control and Life Support System (ECLSS) The ECLSS will maintain the pressurized environment (temperature and pressure) within the cargo requirements during all flight phases, as well crew requirements, while docked. The system will utilize SPACEHAB and ISS heritage hardware and a design similar to other ISS modules in order to minimize crew training and procedure development.
Reentry and Recovery System After successful jettison of the UCM and SM, the PCM performs burns to reenter the Earth's atmosphere with a trajectory targeting landing off the east coast of Florida. The combination of a rigid, ablative nose cap and inflatable heat shield will protect the vehicle during reentry heating. Upon successful reentry, a conventional drogue and parafoil system will slow the vehicle for recovery. A Mid Air Retrieval (MAR) operation will be used to minimize landing loads for the cargo.
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