International Space Station Crew Gets Day Off

The Cygnus spacecraft

The Orbital Science unmanned commercial cargo ship Cygnus, has suffered a mishap which is causing a delay of at least two days in its mission to dock with the International Space Station (ISS). Less than six hours before the expected rendezvous, the brand new cargo ship aborted its docking time because of a computer mishap.

The Cygnus and the International Space Station did establish direct contact early Sunday. The Cygnus spacecraft established contact with the ISS, but some of the data received had values that were not expected, causing the system on the Cygnus to reject the informational data. Because of the rejection, there was an interruption of the approach sequence. This occurred four days after launch from Virginia and until then everything had been doing well.

It will take approximately 48 hours for the Cygnus to do a turnaround because of the interruption, before it can make an approach trajectory to dock with the ISS. The crew members aboard the space station will now have an off-duty day before the upcoming busy week. This could potentially include Tuesday’s Cygnus rendezvous, which will be followed by the arrival of the three new crew members Wednesday. The three crew who are presently on board the ISS will depart from the Balkonur Cosmodrome in Kazakhstan aboard a Soyuz spacecraft.

The computer problem was traced to a data format problem which had happened in the navigational system of both the Cygnus and the International Space Station. The Virginian-based company has already developed a software repair and is in the process of completing the testing on ground before it can be transmitted to the Cygnus, where it will be have to go through more testing.

Before any craft can approach and rendezvous with the ISS for the first time, it must meet the objectives to prove that it is capable before it makes the final capture and docking. When the Cygnus meets these final objectives of pointing a tracking laser at a reflector on the Kibo laboratory, it will move to make its capture point about 10 meters from the station and turn off its thrusters. In a free drift, the Parmitano will maneuver and capture the new resupply craft. The craft will then be moved and attached to the Harmony node.

There is no other problem that has been detected. There is nothing valuable or urgent on board the Cygnus and because of this, it could orbit the station for weeks or months, before docking with the orbiting station. The ship is carrying 1,300 pounds of food and clothes, for the space ship crew of three astronauts, one American, one Italian, and one Russian, who are presently aboard the station.

SpaceX, which is based in California, was the first to accomplish this job for NASA in 2012. Orbital Sciences is the second private sector company to make a flight to the ISS to carry supplies. The supplies are being delivered by private sector space program companies, in the absence of the now-retired space shuttles. Kazakhstan will launch three more crew members this Wednesday, headed for the ISS. If it is not feasible for the Cygnus to be hooked up with the station by Tuesday, Orbital Science will have to work around the manned flight. Completion of the flight would be a big step in the right direction for Orbital Sciences.

Written By: Linda Lafferty

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