A Flock Of Commercial ISS Cargo Birds

Boeing plans to pull the seats, life support and launch-abort system from the commercial crew vehicle it is developing to transport astronauts to the ISS. Like the crew version, the cargo variant will return to Earth with a system of parachutes and air bags on dry land instead of the ocean, an approach the company says will permit many more components to be reused for lower cost. It will also be able to deliver unpressurized cargo within the space freed up in its service module by removal of the launch-abort engines and other crew-safety hardware not needed for the unmanned missions. Credit: Boeing

With an eye toward future exploration beyond the low Earth orbit occupied by the ISS, Lockheed Martin has joined with Canada’s MacDonald Dettwiler Associates and Europe’s Thales Alenia Space to propose a CRS-2 entry that would be “extensible” to missions to geostationary orbit, the Moon and beyond. Based on the spacecraft buses Lockheed Martin has built for interplanetary missions, the Jupiter spacecraft would remain in orbit after launch on an Atlas V and receive additional “exoliners” filled with pressurized and unpressurized cargo from the Centaur upper stages of subsequent Atlas V launches. The bus would use is Canadian-built robotic arm to attach an arriving exoliner and then move it to rendezvous position at the ISS for grappling and berthing by the crew. Later versions could have solar-electric propulsion to reach geostationary Earth orbit, lunar orbit and perhaps more distant objectives. Credit: Lockheed Martin Concept

Orbital ATK developed the Cygnus capsule and Antares medium-lift launch vehicle to deliver cargo to the ISS under NASA’s COTS program and later won a $1.9 billion CRS-1 contract for eight flights to the ISS. The vehicle has reached the ISS three times, including a demonstration flight in September 2013. The Antares suffered a launch failure Oct. 28, 2014, costing the station a load of cargo. To keep its contract commitments, the company plans to use an Atlas V to launch its next Cygnus. That “enhanced” variant, with a larger cargo capability, will return to Antares launches once that vehicle is equipped with a new engine, the Russian-built RD-181. Credit: NASA

Sierra Nevada Corp. was unsuccessful with its proposal to fly crews to the ISS on a reusable lifting-body spaceplane it dubbed Dream Chaser. It has proposed an autonomous version of the vehicle for the new cargo competition, with provisions for pressurized and unpressurized payloads. While the piloted version of Dream Chaser was designed to launch in the open atop an Atlas V, the cargo variant would be able to fold its lifting-body “wings” to fit inside the fairings of a variety of launch vehicles for greater operational flexibility. Like the commercial-crew variant, it would be able to glide to a low-g runway landing and be reusable. Credit: Sierra Nevada Corp.

Like Cygnus, the SpaceX Dragon is an incumbent in the second-round station-resupply competition, with a 12-flight, $1.6 billion commercial cargo-delivery contract with NASA. Since May 2012, the spacecraft has berthed with the ISS six times, including a demonstration flight that also delivered cargo. The Dragon is the only vehicle flying now that is able to return a significant pressurized payload (3,000 kg) to Earth, using a parachute-assisted water landing off the coast of California. It can carry both pressurized and unpressurized cargo to the ISS. Like Boeing, SpaceX is developing a crew version of Dragon under NASA’s commercial crew vehicle program. Credit: NASA