Related topics

URGENT NASA Loses Contact with Magellan Again

August 22, 1990

PASADENA, Calif. (AP) _ Engineers lost radio contact with the Magellan spacecraft Tuesday night for the second time in five days, NASA said.

Scientists weren’t immediately sure if the spacecraft’s computer circuits would send out a radio beam in an attempt to re-establish communication with Earth, as the Venus-orbiting craft is supposed to do in an emergency, NASA said.

Magellan’s mission is to map up to 90 percent of Venus’ surface using radar to peer through the planet’s thick clouds, which prevent the use of optical cameras. The spacecraft went into orbit around Venus Aug. 10 after a roundabout, 948-million-mile trip. It was launched from the shuttle Atlantis 15 months ago.

″They lost it at 7:03 p.m. PDT″ while tracking the craft with a NASA antenna dish near Canberra, Australia, said Jim Doyle, spokesman for NASA’s Jet Propulsion Laboratory.

The mishap came only hours after NASA released the spacecraft’s first pictures of Earth’s closest planetary neighbor. They showed Venus has quake faults, lava flows like those in Hawaii and Idaho, and long, parallel valleys and ridges similar to those between the Sierra Nevada and the Rockies.

The loss of Magellan, the centerpiece of a $744 million mission to explore Venus, would be a major blow to NASA, which grounded the shuttle fleet temporarily because of fuel leaks and found the Hubble Space Telescope had a flawed mirror.

Doyle said that if the craft was beaming radio waves across the sky while spinning - as it is supposed to do to in an emergency - engineers could re- establish intermittent contact between 12:03 and 12:30 a.m. PDT Wednesday.

Less than seven hours before contact broke off, project manager Tony Spear said that as far as engineers could tell, ″the spacecraft is healthy,″ despite a loss of contact for more than 14 hours starting last Thursday night.

The spacecraft’s automatic self-protection system made Magellan re- establish with NASA engineers last Friday morning. Then, they sent Magellan a command to make it stop spinning and stay in touch with Earth.

Engineers said they still haven’t figured out why they lost contact with Magellan last week.

One leading theory is that a cosmic ray or a high-energy particle from the sun caused a blip in Magellan’s computer memory, said spacecraft system engineer John Slonski.

″We’re not ruling out a software flaw or some hardware problem″ or perhaps some unknown electrical fields surrounding Venus, Spear said.

Cosmic ray ″hits″ on spacecraft electronics can be expected to interfere with Magellan about once each year, Spear said. Similar events occasionally have disrupted the Pioneer Venus Orbiter, launched in 1978, and the Tracking and Data Relay Satellites in Earth orbit, Slonski said.

The pictures released Tuesday were taken during an Aug. 16 test when Magellan bounced its radar beam off Venus for the first time.

As promised by NASA, the pictures are 10 times more detailed than the best radar images of Venus made by the Soviet Venera 15 and 16 spacecraft and by the radio telescope at Arecibo, Puerto Rico. They show details as small as 400 feet across, or a third bigger than the length of a football field.

The large number of fractures and ″Venusquake″ faults seen in images from the spacecraft suggest the crustal movements that shaped the landscape are ″perhaps even more violent than I imagined before,″ said Steve Saunders, Magellan’s chief scientist at Jet Propulsion Laboratory.

″Overlapping lava flows of various ages″ and six to 10 miles wide appear as bright and dark splotches, he said.

But Saunders said the pictures don’t yet show any of Venus’ major volcanoes, whether any of them are active or if the planet’s crust is broken into the kind of drifting plates that carry whole continents across the face of the Earth. Previous spacecraft revealed numerous mountainous volcanoes.

The lava flows are ″similar geologically to volcanic deposits seen on Earth at Hawaii and the Snake River Plains in Idaho,″ NASA said in a statement.

The parallel sets of elongated valleys and ridges resemble those in the basin-and-range province of the intermountain region of Utah and Nevada, or at the Great Rift Valley in eastern Africa. They show that at least part of Venus’ crust has been stretched apart, Saunders said.

Update hourly