Thursday, July 17, 2014

ICE Spacecraft Recovery Effort Appears at an Impasse

According to a July 10 National Public Radio (NPR) "Morning Edition" report, the effort to recover the venerable International Sun-Earth Explorer 3 spacecraft (ISEE-3) -- later repurposed, redirected, and renamed the International Cometary Explorer (ICE) -- has run into problems and may have reached a dead end. The ISEE-3 Reboot Project has been trying since July 8 to fire the engines of the 36-year-old space traveler without apparent success. The spacecraft is some 2.65 million miles from Earth. The team, which includes several Amateur Radio operators, has been transmitting control signals from the Arecibo Observatory in Puerto Rico and listening for spacecraft telemetry at the Bochum Observatory in Germany. The pessimistic NPR report featured team member Keith Cowing, a former NASA engineer.

"Our first series of burns, we thought went okay," Cowing told reporter Nell Greenfieldboyce. "And then when we went to the second set, pretty much nothing happened. And we tried it again, and nothing happened." The group has conjectured that the nitrogen tanks needed to pressurize the hydrazine fuel on the spacecraft may be empty, meaning that the engines are dead, and the team will not be able to redirect ICE into an orbit that is closer to Earth, instead of letting it fly past the planet.

"At this point, we're sort of scratching our heads," Cowing said. "We may take one last run at the spacecraft, but this may be it for an attempt to bring it back to Earth." ICE has been in a solar orbit for most of its life, following its 1978 launch.

In late May, Dennis Wingo, KD4ETA, a project team member and the CEO of California-based Skycorp Incorporated, reported that the team was able to command one of the spacecraft's transponders on 2.042 GHz by radio.

The group has been hoping to place ICE into a gravitationally stable spot some 930,000 miles from Earth -- essentially its original orbit -- where it could again study the effects of solar weather on Earth's magnetosphere (the project's slogan is "Make me do science again!"). The private group had to obtain NASA's approval to communicate with the satellite.

Cowing said in a July 15 update that the team's next window of opportunity would be July 16 at Arecibo. "During that opportunity we intend to attempt a deep space plumbing repair on board ISEE-3 and then fire its engines," he said. "Based on the number of thruster firings we achieve during that plumbing repair session we'll need to do some additional firings -- possibly over the course of several days -- all of which will constitute the [trajectory correction maneuver].

"We have most certainly not given up on this spacecraft yet," Cowing said July 10.