Hunt is on for pieces of van-sized California meteor

Wanted: fragments of a minivan-sized meteor that exploded over northern California and Nevada on Sunday morning and may well have survived to strike Earth.

Meteorites – meteors that make landfall – can provide crucial information about the chemical composition of the early solar system.

"It's like getting sample return without having to go there," says Bill Cooke of NASA's Meteoroid Environment Office at the Marshall Space Flight Centre in Huntsville, Alabama.

However, meteorites are rare. Though meteors frequently streak across the sky, they tend to burn up before reaching the ground or they land in the sea. There's reason to think the recent meteor is different.

Apart from exploding over land, it created a sonic boom, so it must have stayed intact for long enough for it to get down into the denser air low in the atmosphere – just 16 kilometres above the Earth's surface, Cooke reckons – raising the chance that some of it hit the dirt.

Sudan similarity
He estimates it was about 4 metres long, about 70 metric tonnes and packing the energy of 4 kilotonnes of TNT. "That's about one-fourth the energy of the 'Little Boy' bomb dropped on Hiroshima," he says.

That makes the rock even bigger than 2008 TC3, a meteorite which was detected before it entered the atmosphere and became the first cosmic impact to be traced from space to landfall when astronomers found its scattered fragments in Sudan in 2008.

Cooke is also hoping someone took a video of the new meteor.

Astronomers used infrasound signals – low frequency sound that travels great distances – detected at two ground-based stations to pinpoint the spots where the new meteor entered the atmosphere and then exploded. They don't yet know where the fragments went.