The Spacecraft
The ARCTUS design uses flight-proven components to reduce development
costs and program risk. This approach eliminates most of the program's
non-recurring engineering labor costs and, with minimal modification
of existing components, accommodates ISS cargo requirements. Finally,
it is compatible with existing, flight-proven launch vehicles,
payload requirements and interfaces. |
Structures
ARCTUS is comprised 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 ISS interface (Common Berthing
Mechanism, CBM), and the spacecraft Propulsion System.
Separation
mechanisms are used to allow for separation of the
UCM and SM prior to reentry of the PCM. Automated Rendezvous and
Proximity
Operations (ARPO) System
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 Node 2 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.
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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.
Page Last Updated: 12.07.2007
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