The Orbital Transfer Vehicle (OTV) is really nothing more than a standard space vehicle with propellant tanks and a rocket engine. The basic OTV design has been around for half a century (Image A).
The top of the space truck will have the USIS Docking Ring to mechanically connect payload.
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| Image A: The OTV internal view |
Between the LH2 and LO2 tanks is the Intelligence Module (IM). Electrical power will be provided by a fuel cell being fed cryogenics.
The IM also houses the 4 Reaction Control System (RCS) quads. The quads will burn 3 kg of propellant per day including boiloff. A total of 12 kg will be consumed per day, which gives an eight day operational duration.
The OTV will have the propellant tanks replenished for refurbishment and reuse.
The Cargo Hold Guide Rails (CHGR) are used to secure the OTV to the VentureStar Cargo Hold.
The exterior of the space truck (Image B) will be painted white to help offset increased internal heating. The RCS will be located in each of the rounded corners.
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| Image B: The OTV external views |
RCS propellant mass is summarized in Table 1.
Our spacecraft begins its life as a Universal Module (Table 2). This module is the basic building block upon which other components are attached.
Table 2: The Universal Module specifications
The OTV inert mass specifications are summarized in Table 3, and the OTV propellant mass specifications are summarized in Table 4.
Stage Mass = Inert Mass + Propellant Mass
Stage Mass = 2570 + 18053
Stage Mass = 20,623 kg
Mass Ratio = Propellant Mass / Stage Mass
Mass Ratio = 18053 / 20623
Mass Ratio = 0.875
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