HONOLULU - Before Apollo astronauts went to the moon, they went to Hawaii to train on the Big Island's lunar landscapes.

Now, decades-old photos are surfacing of astronauts scooping up Hawaii's soil and riding across volcanic fields in a "moon buggy" vehicle.

The Pacific International Space Center for Exploration Systems, a Hawaii state agency, is displaying the photos at its Hilo headquarters. Rob Kelso, the agency's executive director, found the images at the Johnson Space Center in Houston.

Astronauts from Apollo missions 13 through 17 trained in Hawaii as did some back up crews, Kelso said.

Some training was on Mauna Kea volcano, where glacial runoff crushed and refined rock into powder. Astronauts also trained on recent lava flows.

Today, robots are tested on the Big Island for moon and Mars missions.

In recent years, engineers have tested technology to pull oxygen out of the island's dirt, which is volcanic basalt like the Martian and lunar soil. Future missions could use this technology to extract oxygen from the land instead of taking it along. The oxygen could be used for breathing, to make fuel or for other purposes.

Kelso said scientists are also interested in testing robots at the Big Island's lava tubes and lava tube skylight holes, which resemble similar formations recently spotted in high-definition images taken by satellites orbiting the moon, Mercury, Venus and Mars.

Lava tubes are tunnels made when lava forms a solid roof after flowing steadily in a confined area for hours. Skylight holes are formed when part of the tube breaks.