- WASHINGTON (Reuters) - Tiny crystals growing in the vacuum of space on critical
electrical relays caused widely publicized problems on three satellites
made by Hughes Space and Communications Co., the company announced Tuesday
after a massive investigation. But the company's engineers were unable
to pinpoint the cause of the most serious problem that led to the demise
of PanAmSat Corp.'s Galaxy IV satellite, knocking out pager service across
the country for a week in May. Hughes, a unit of Hughes Electronics Corp.,
said the failure of Galaxy IV was most likey the result of a one-time,
random event that would not jeopardize the 35 similar satellites currently
in orbit. In the other cases, growth of crystals less than the width of
a human hair caused electrical switches plated with tin to short out inside
devices that kept the satellites pointed toward their controllers on Earth,
the investigation concluded. The company said it was still reviewing manufacturing
records to determine how many of the 35 satellites aloft might be susceptible
to electrical shorts in tin-plated relays. Customers include the U.S. Navy,
NASA, the government of Mexico and communications companies worldwide.
An electrical short in a tin-plated relay hit PanAmSat's Galaxy IV last
year and its Galaxy VII satellite, used mostly by television broadcasters,
in June. An identical short also occured in a satellite owned by another
Hughes unit, DirecTV, in July. In all three satellites, versions of Hughes
popular HS601, back-up systems kept the spacecraft operating normally.
It was the May 19 failure of Galaxy IV's back-up, not related to a tin-plated
relay, that led to the dramatic pager black-out and illustrated the country's
growing dependence on high-tech communications services. Hughes said it
had stopped using the troublesome relays in its satellites several years
ago and launches of new spacecraft, including PanAmSat's launch of the
Galaxy X later this month, could proceed. ``We are confident that this
scenario that this scenario will not be repeated in the satellites that
are being built and launched today,'' Hughes Chairman Michael Smith said.
PanAmSat said five of its 16 satellites have tin-plated relays but the
chance of another complete spacecraft failure was ``very low.'' The Greenwich,
Conn., company said it would launch nine new satellites over the next 18
months to enhance communications capacity and add redudancy. The company's
customers include major telecommunications carriers, news services and
broadcaster networks. ``This ambitious expansion plan will double our total
transmission capacity over the next 18 months, assuring that PanAmSat continues
to provide a robust and growing global satellite communications network,''
company President Frederick Landman said.