"This side up" should have been the label on switches inside the Genesis spacecraft.

That's the gist of what went wrong with the Genesis probe, which slammed into the mud of Dugway Proving Ground Sept. 8. After three years and 1.86 million miles in space, the craft with its precious cargo of solar wind samples failed when it was on the brink of success.

Instead of a midair catch by a helicopter equipped with special capture gear, the probe crashed on the desert floor. The impact ripped open the spacecraft and the science capsule inside — most of the 3,000 glassy collector plates were broken, though some survived intact.

Scientists are hopeful they can retrieve useful data from the broken plates, so the $264 million project may not be a loss.

On Thursday, NASA's Genesis Mishap Investigation Board issued a preliminary report concluding "the likely cause was a design error that involves the orientation of gravity-switch devices." The report says the switches may not be the only flaw, and study of the debris continues near Denver.

But the crash was blamed on gravity switches, said Michael G. Ryschkewitsch, chairman of the investigation board, who spoke with the Deseret Morning News Monday from NASA's Goddard Space Flight Center in Greenbelt, Md. The switches "sense the deceleration when the capsule enters the upper atmosphere."

"And in the case of Genesis, the gravity switches were installed by design in a position reversed from the position they should have been."

The circuit card with the gravity switches was designed and installed by contractor Lockheed Martin in Denver, Ryschkewitsch said. However, he added, the project was part of a NASA program run by the Jet Propulsion Laboratory in Pasadena, Calif., and JPL was responsible for a number of reviews before launch.

The Deseret Morning News made five attempts to reach officials at Lockheed Martin on Monday but was unsuccessful.

An important question is why NASA's tests and reviews did not catch the flaw, said Ryschkewitsch.

When the spacecraft hit Earth's atmosphere on its return trip, it was traveling about 25,000 miles per hour, and air drag caused it to decelerate. At that point, the gravity switches — each described as a small plunger on a spring — were supposed to cause the drogue parachute to deploy.

Deceleration should have pushed the plunger onto an electrical contact, the way a person feels the seat belt pressing when a car suddenly slows. On Genesis, when deceleration dropped further, the spring was to push the plunger back from the contact.