Parom subsystems would be upgraded versions of those proven on the Soyuz TMA spacecraft.
Parom would have two active docking units: one for docking to the payload and the other for docking to the ISS. Parom's propulsion system would be designed for refueling and very long-term storage of hypergolic storable propellants. Solar arrays would provide power.
Between missions Parom would remain docked to the ISS. When a payload was launched for the ISS, Parom would separate, rendezvous and dock with the payload, transport it to the station, and then dock automatically with the station. A small pressurized module within Parom would provide an airlock between the station and any pressurized compartments of the payload canister or spacecraft requiring unloading. After the cargo was unloaded and filled with trash, Parom would separate from the station, jettison the container into an orbit ensuring it would burn up over the south Pacific, then return to the ISS to await the next payload launch.
Cargo containers would be kept simple to reduce cost. An unpressurized portion would have propellant tanks for refueling Parom or the ISS. Equipment aboard the container would be limited to a module providing minimal attitude control using electric flywheels, and a passive docking unit. Containers could be designed for launch by either Soyuz or Proton launch vehicles, and deliver from 4 to 13 metric tons of payload depending on the launch vehicle and mission profile. Therefore the payload delivered by the existing Progress resupply spacecraft using a Soyuz launch vehicle - 2 metric tons - would be doubled using the Parom concept.
As of 2006, Russia planned the first Parom launch in 2009 - as always, subject to delays due to unavailability of development funding.
Parom would have a dry mass of 5990 kg, and as first launched by Soyuz, a gross mass of around 7000 kg. However if launched by a Proton, the initial mass fuelled could be as much as 12,500 kg. It could accommodate modules of 3.2 m diameter and 26 cubic meters of payload. Capable of free flight durations of up to 180 days, it was to be designed to handle 60 tug missions over a 15 year period.
Gross mass: 5,990 kg (13,200 lb).
Height: 6.55 m (21.48 ft).
Diameter: 3.20 m (10.40 ft).