A Trinity College astronomer controlled the operation of a Nasa rocket flight sent to study the sun yesterday, writes Dick Ahlstrom
An Irish scientist sitting in Dublin yesterday dictated the operation of a US rocket fired from the deserts of New Mexico. The probe was sent aloft in an attempt to answer one of the great unsolved mysteries of modern physics - what makes the sun so hot.
It is not the sun's surface that worries the scientists but its corona, the super-hot atmosphere above the surface, explains Trinity College Dublin astrophysics lecturer, Dr Peter Gallagher. The surface itself is about 5,725 degrees but for some reason the solar atmosphere reaches a far toastier two million degrees.
"We don't know why it is two million degrees," says Gallagher. "It appears to violate all the laws of thermodynamics we understand. As you move away from the surface into the corona, the temperature jumps up." This temperature gradient was noted 40 years ago but astrophysicists have only been able to speculate about the cause. The launch of two probes, Eunis and Moses, may help settle the "coronal heating debate", he says.
Moses was due to go up at about 6pm Irish time yesterday and Eunis is due to follow this Saturday. Gallagher has the onerous task of dictating what Eunis and Moses should look at during their 20-minute sub-orbital flights.
Moses was due to reach an altitude of about 300 kilometres. The probe itself should only have begun working after the rocket shut down and the probe's momentum sent it into a smooth parabola to give the researchers about 10 minutes of solar viewing time. It would then have drifted on a parachute to be recovered 80 kilometres downrange from the White Sands Missile Range in New Mexico, carrying billions of bits of data in hundreds of solar images captured by its onboard camera.
The two probes don't sport conventional cameras. Eunis carries a new type of digital camera, a CMOS active pixel sensor. Moses carried another new device that could capture images simultaneously at several different wavelengths in the extreme ultra violet light range.
There are two key objectives to the mission, which cost several hundred thousand dollars, says Gallagher.
One is to prove that the new cameras would work and capture clean images very quickly. "The other one is we hope to be able to get high quality data to understand the coronal heating problem." Gallagher is from Dublin but only recently returned to Trinity after five years in the US, the last three working at NASA's Goddard Space Flight Centre outside Washington. His lab at Trinity is responsible for aiming the cameras at specific targets on the solar disc. Gallagher has become an expert at studying features on the surface after developing software that automated the analysis of solar images. His lab will now also help interpret the data returned by the probes.
He was given this role because of his expertise. "I developed a lot of image processing software that automated the analysis of [ solar image] data," he says. "People started coming to me to discuss what features were there. Before this the analysis was done by eye. I ended up working with the SOHO [ solar observatory] satellite project. I was doing a lot of co-ordination of the observations."
Other teams in Queens University Belfast, Goddard, Montana State University, the US Naval Research Laboratories and University College London will handle other aspects of the mission.
Two main theories attempt to explain the coronal heating problem, he says. One suggests the higher temperatures are caused by waves coming up through the surface to cause powerful shock waves. Another holds that millions of "microflares", too small for our telescopes to see, are heating up the corona.
The new cameras will really be put to the test, he adds. "We need to get fast pictures because if there are waves they are predicted to be moving extremely fast," he says. They will also have to be very sensitive to record any trace of microflares. It will take at least two years' analysis before scientists can come to any conclusions about the solar corona, however.