Commercial Deorbit Capability for ISS Sought by NASA
NASA is soliciting responses from interested parties to gauge industry’s capabilities to provide commercial deorbit capability for the International Space Station (ISS).
The agency has issued a Request for Information (RFI) to assess industry’s capability to design, develop, manufacture, launch, and provide the on-orbit operation to enable a controlled re-entry and the safe deorbit of the ISS.
The RFI specifies that the deorbit vehicle will be attached (via docking or berthing) to the ISS at least one year prior to the planned ISS reentry date to enable adequate time for on-orbit tests and checkouts. ISS altitude lowering can occur naturally via atmospheric drag or via Russian propulsive control from the deorbit vehicle rendezvous altitude to the final circular holding altitude at approximately 270 km (≈168 miles), where maneuvers will be performed as necessary to establish proper ground tracks prior to the final deorbit burn sequences. Below 270 km, a combination of natural decay and/or propulsive maneuvers will reduce the ISS perigee to approximately 150 km (≈93 miles). Shortly thereafter, the deorbit vehicle will perform the final reentry burn resulting in a controlled reentry of the ISS within a pre-defined, uninhabited entry corridor. Throughout the final series of deorbit events, the deorbit vehicle will be responsible for providing both delta-v and attitude control of the ISS.
Although nominal ISS End of Life (EOL) is late 2030, the Government requires that this deorbit capability be available as soon as possible to protect for contingencies that could drive early re-entry and beyond 2030 in the event of further ISS mission extensions.
Among the ground rules and assumptions in the RFI are:
The deorbit vehicle design and operations shall enable a contingency call-up for launch on-need to support an earlier than nominal plan deorbit scenario. This call may be made as late as L-6 months prior to the needed deorbit date.
The deorbit vehicle design and operations shall support a later than nominal plan deorbit scenario due to the extension of the ISS EOL beyond 2030.
The deorbit vehicle shall remain on-orbit in a quiescent mode for a minimum of one year preceding the final deorbit burn.
The deorbit vehicle design may require complex software development including autonomous operations and failure response late in the deorbit phases.
The deorbit vehicle is a must-work function.
The deorbit vehicle shall be capable of providing at least 47 m/s of delta-v for the ISS at 450,000 kg mass.
The deorbit vehicle shall provide a minimum total thrust of 3236 N.
The deorbit vehicle shall provide attitude control for the mated stack throughout the deorbit sequence of events.
Additional detail on the concept of operations can be found in the “ISS Deorbit USOS Concept of Operations Overview” presentation linked here.
(Source: NASA. Image from file)