SETI@home's plans to reobserve its most promising candidate signals were interrupted today by the unexpected intervention of a Solar flare. Instead of eight full hours of observations on Wednesday, the SETI@home team had to settle for a short two-hour window from 4pm-6pm Atlantic Standard Time. Like all the other scheduled telescope users, they were bumped off the telescope to allow for radar observations of the Earth's upper atmosphere, which may be impacted by the Solar event.
"We had a good run" team leader Dan Wethimer said of the shortened session "but we still didn't find ET." At one point during the afternoon the radio telescope did detect an "interesting" signal from one of the locations, and Werthimer and his team decided to scan it one more time. At the moment it does not appear that there was persistent signal there, but final analysis will have to wait until the team returns to Berkeley.
In addition to today's observation session, the SETI@home team was scheduled to continue their observations for an additional eight hours on Thursday. This session has also been cancelled. In its place, SETI@home has been granted 14 straight hours of observation on Monday, March 24.
The change in plans, according to Dr. Sixto Gonzalez, Assistant Director for Space and Atmospheric Sciences at the Arecibo Observatory, was caused by the eruption of two Solar flares on Monday and Tuesday (March 17 and 18) of this week. The eruptions were observed by NASA's SOHO spacecraft, which transmitted the data to Earth. It takes a few days before the radiation emitted by such eruptions interacts with the Earth's magnetic sphere, but when it occurs it can have unexpected results. Similar events in the past have been known to interfere with communications and global positioning satellites.
The Arecibo radio telescope is part of a global consortium of observatories, both radio and optical, committed to tracking the effects of Solar flares on Earth's upper atmosphere. Whenever an eruption takes place, observing it takes priority over the scheduled telescope activities. "We cannot control the eruption of Solar fares," explained Gonzalez; "we just have to observe them when they occur."
For the next few days, beginning Wednesday, March 20, and ending Sunday, March 23, the Arecibo radio telescope will be used as a giant radar, sending out electromagnetic bursts that will bounce off the Earth's upper atmosphere. The radar observations will begin before the arrival of the Solar radiation and continue during the Solar storm.
"There is always the possibility," explains Gonzalez, "that the Solar storm will completely miss the Earth" and will therefore have no effect. But if it does impact the Earth, Gonzalez and his colleagues want to be sure that Arecibo is ready for it. The information gathered by the radio telescope will help scientists understand the impact Solar flares have on the Earth's upper atmosphere. In the long run, as scientists learn more about these events, it may be possible to predict their impact on the Earth, and perhaps prepare for it.
And so, SETI enthusiasts will have to wait a short while longer before they learn if an ET signal is hiding among SETI@home's "best signal candidates." But after waiting for millennia for a sign from the stars, a few more days won't make much of a difference.