NASA Probe To Map Solar System's Edge

A small NASA spacecraft embarks on a two-year mission this weekend to give scientists their first view of the happenings at the edge of the solar system.

The Ibex probe, short for Interstellar Boundary Explorer, will study a chaotic region in space where the solar wind from the sun clashes with cold gases from interstellar space.

The solar wind, a stream of charged particles spewing from the sun at 1 million miles per hour, carves out a protective bubble around the solar system. This bubble known as the heliosphere shields against most dangerous cosmic radiation that would otherwise interfere with human spaceflight.

Scientists recently discovered that the solar wind pressure is at its weakest level in 50 years, although the exact reason remains a mystery. Ibex could help confirm whether the heliosphere is shrinking.

Observations from Ibex should help researchers in "unlocking the secrets of this important interaction between the sun and the galaxy," said David McComas of the Southwest Research Institute in San Antonio. He is chief scientist for the $165 million mission.

Ibex, the size of a bus tire, will be launched aboard a Pegasus rocket that will be dropped from an aircraft over a Pacific atoll on Sunday.

The rocket will lift Ibex 130 miles above Earth and put it into orbit. The spacecraft will then fire its solid rocket motor to loft itself even higher, eventually to 200,000 miles above Earth.

Ibex will build on the discoveries of the long-running twin Voyager spacecraft launched in 1977 to explore the outer planets. The deep-space, manmade probes have since sailed past the outer planets and are headed out of the solar system.

Unlike the Voyager craft, Ibex will not barrel through space, but instead will do its job from high-Earth orbit. The probe carries two sensors that will collect information about the solar wind's mass and energy from all directions.

NASA sees no quick fix for broken Hubble telescope

NASA's efforts to get the ailing Hubble Space Telescope working again have hit a snag, and engineers are trying to figure out their next step.

Officials had hoped to have the 18-year-old observatory back in business Friday, after it stopped sending pictures three weeks ago. But a pair of problems cropped up Thursday, and now recovery operations are on hold.

It's unclear how long the telescope will be prevented from transmitting its stunning photos of the cosmos.

The soonest it could be operating fully again is late next week, said Art Whipple, a Hubble manager. At worst, the observatory might remain inactive until astronauts arrive with a replacement part next year.

"We're still optimistic," he told reporters Friday.

Flight controllers at Goddard Space Flight Center in Greenbelt, Md., began the lengthy process of restoring data transmission on Wednesday. Everything was going well, until late Thursday afternoon.

First, a low-voltage power supply problem prevented one of Hubble's cameras from being rebooted properly, and then computer trouble struck and all efforts ceased.

It's too soon to know whether the two problems are related, said Whipple.

"We're in the early stage of going through a mountain of data that has been downloaded over the last 24 hours," he said at a news conference.

Hubble's command and data-handling system for science instruments failed late last month and prevented the telescope from capturing and beaming down data used to create the pictures for which Hubble is known.

Because of the breakdown, NASA delayed its final Hubble repair mission by shuttle astronauts that was set for October. The mission won't happen until at least February, possibly later.

The latest setback is not expected to further delay the shuttle mission, Whipple said.

The recovery efforts involved switching to a backup channel for the command and data-handling system that had been dormant since the telescope was launched in 1990. That part, at least, seemed to go well, Whipple said.

So far, this isn't the longest that Hubble has been inactive since NASA's 1993 mission to correct its blurred vision. In 1999, science operations were halted about six weeks because of gyroscope failures that were remedied by astronauts whose flight quickly followed the breakdown.