SOLAR SYSTEM BABY

Japan's Hayabusa spacecraft that landed twice on the asteroid Itokawa found it to be a "rubble pile" of 4.5-billon-year-old planetary debris that loosely coalesced only about 10 million years ago, rather than a much older intact body like previous asteroids visited.

This means researchers discovered--180 million mi. from Earth--a new baby of the solar system. It's just one of many findings from the $100-million mission that will affect theories on the formation of planets and small bodies around the Sun and other stars.

In addition to being perhaps the youngest known object in the Solar System, the asteroid is likely a "contact binary--a joined pair of earlier separate objects--the first such conjoined twins ever viewed up close in deep space. The juncture between two objects is clearly visible as a smooth neck area between a rounded head and an elongated body. There are plenty of rocky boulders up to 150 ft. in diameter, but minimal evidence of significant craters and regolith that would show the object to be older.

The Hayabusa data are a reminder "to expect the unexpected" in planetary exploration, said mission managers at the 37th Lunar and Planetary Science Conference here in mid-March.

One new revelation is that during one landing, the spacecraft bounced twice, then remained on the surface an unexpectedly long 35 min. These bounces and long dwell time could have given asteroid material, disturbed in microgravity, enough time to inadvertently float into the spacecraft's collection device, even though a sample blasting mechanism did not fire properly.

The Hayabusa observations will be a significant element in international planning for future missions to asteroids and comets. Japanese Aerospace Exploration Agency (JAXA) managers say the striking findings, and relative success of the mission, will cause them to elevate future asteroid missions for approval.

As an Earth-crossing asteroid, Itokawa has a reasonably high statistical chance of striking Earth in a million or more years from now, JAXA says. The agency says this means the Hayabusa data are important for risk assessments for other asteroids colliding with Earth possibly much sooner with potential catastrophic consequences for mankind.

Several independent researchers here said the data assure a lasting legacy for the mission, even if it fails to return samples of the asteroid, its primary goal.

The mission in deep space has been an ongoing drama for the last six months. Hayabusa landed on the asteroid twice in November in an attempt to collect samples. Spacecraft telemetry, however, indicates it's doubtful the sampling system worked properly. But that's yet to be determined, and samples may actually be on board.