SOHO's new software works perfectly - scientists and engineers overjoyed
5 October 1999Much to the elation of scientists, the Solar and Heliospheric Observatory is back in top gear with its newly installed software running flawlessly. "Everything is just perfect," said Bernhard Fleck, SOHO ProjectScientist. "These engineers have been absolutely fantastic. They puttogether a completely new flight software in less than a year undertremendous pressure. They have been great and this is a tremendousachievement."
During a week-long battery of tests on the software, SOHO was put on a reduced observation programme. "We had no problems at all," said Francis Vandenbussche, SOHO System Engineering Manager. "Everything went really on schedule. All the functions of the new software are working perfectly well." The new software, sent up to the spacecraft on 27 September, is designed to make SOHO sturdier and more dependable in case the spacecraft experiences orientation problems.
During the tests, SOHO remained stable enough for some of the instruments to conduct observations even as Matra Marconi and ESA engineers at NASA's Goddard Spaceflight Center in Greenbelt, Maryland (USA), conducted their tests working 12-hour days. "We have shown that we have a spacecraft that even in emergency mode could provide good science," said Michel Verdant, ESA's SOHO Program Manager.
In 1998, SOHO disappeared in space and control was regained only after several weeks. Then the spacecraft lost all of its three gyroscopes. The new software is designed to prevent a repeat of those problems and to allow the spacecraft to determine its own orientation even without aid from the gyroscopes. And that is an absolute first in the history of space exploration!
SOHO is a cooperative effort between ESA and NASA. The spacecraft was launched in December 1995 to a so-called halo orbit 1.5 million kilometres from Earth. Even though the spacecraft's nominal mission was to last 2= years, it is now funded and expected to continue until March 2003.
In theory, and especially with the new software, the mission could be extended even further. Said Vandenbussche, "From a fuel standpoint, we have still 120 kilograms, and we have been using only a few kilograms a year. So we could last another 10 to 20 years." Vandenbussche also praised the team of engineers he headed since 1998: "It was a fantastic team that held very well under a lot of stress. They were totally dedicated to their job and to a complete success."
At the Goddard Spaceflight Center, for SOHO scientists who had developed personal relationships with members of the recovery team, it was a bittersweet moment. "This afternoon, they are going back to Europe and we are a bit sorry to see them leave," Fleck said. This is kind of a farewell. "The recovery is over and the book is closed, and we may not see them again for a long time."