Russian and European specialists working on the main computer of the yet-to-be launched Zvezda module -- a critical part of the International Space Station -- have solved a major problem plaguing the spacecraft.
Computer experts found a glitch last week that was disabling Zvezda's main computer, supplied by the European Space Agency, said a Russian space company official.
"They will need some time to implement the corrections," said Yuri Grigoriev, Deputy to the Designer General of RKK Energia, the leading Russian company working on the International Space Station ISS).
Grigoriev confirmed that a number of other issues with Zvezda's onboard flight control software still remain. He said since both the U.S. and Russia are working on the project, it would be unfair to blame the Russians alone for the software's problems. For example, testing delays in the U.S. compromised the Russian work schedule on the flight control system. The Zvezda module has 15 computers onboard that are responsible for flight control.
Ongoing software problems had a domino effect on several other aspects of the long-delayed Zvezda launch, including crew-familiarization training currently conducted in Baikonur, updating ground-based training equipment and finalizing the technical documentation for the module.
While Grigoriev said that Zvezda's hardware could be ready for the module's launch this year, he refused to predict exactly when it will take off, saying a realistic time for the launch is the first quarter of 2000. As space.com reported, Zvezda's launch date could be set during the Council of Chief-Designers review. This was first planned for the end of October. But due to remaining unresolved issues, it will be further delayed. Grigoriev said the review could now take place between November 15 and 25.
Even if the existing software problems are solved, a number of other issues can still affect Zvezda's launch date.
Grigoriev said that to best track Zvezda's flight, the Russian mission control team will need a data relay satellite in place before module's launch. The satellite would transmit data from Zvezda when the spacecraft is beyond the reach of Russian ground control stations.
At least one data-relay spacecraft, an Altair-type satellite, is in production by the NPO-PM company of Krasnoyarsk, Russia. It could be launched in three or four months, if the necessary funds are provided.
Altair-type satellites, launched by heavy Proton boosters into geostationary orbit, have been used to relay data from Mir in the past. Replacement satellites have not been launched due to a lack of funds. Along with the relay satellite, the existing network of ground control stations also must be updated.
RKK Energia is also producing the supply ships that will be used for ISS operations in the second half of 2000, possibly causing further delay. The company has already completed two Soyuz capsules and three Progress cargo ships. However, it will have to supply a total of six or seven Progress vehicles for the ISS operations planned for 2000.
Also, an additional Soyuz spacecraft will be needed if RKK Energia goes ahead with its plans to launch another crew to the Mir space station.
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