It was evening in the U.S.A. when the IRIS (Interface Region Imaging Spectrograph) space probe was launched using an Orbital Science Pegasus XL rocket brought to an altitude of about 13,000 meters (about 39,000 feet) by an airplane Orbital Science L-1011 modified for this purpose. In a short time, IRIS has been brought into a Sun-synchronized polar orbit, where its solar panels deployed regularly and it sent the first signals.
The IRIS spacecraft will aim an ultraviolet telescope towards the region of the Sun between its surface and the area of the outer atmosphere called the corona. With its observations it will allow us to understand how energy moves from the surface to the corona warming from a temperature of about 6,000 degrees Kelvin to reach millions of degrees.
Various theories have been developed to try to explain the reason why the Sun’s atmosphere becomes warmer – and so remarkably – moving away from the surface. So far, however, there were no sufficient data to give a precise answer and the observations of the IRIS spacecraft should improve the situation.
Thanks to its telescope, the IRIS space probe will also examine the Sun’s chromosphere, the atmosphere’s layer under the solar corona, with the highest detailes ever obtained so far. In this way, it will complement the observations of NASA’s Solar Dynamics Observatory (SDO) probe and the Hinode probe, a JAXA – the Japanese space agency – mission in which NASA has collaborated. In fact, together these probes will be able to monitor the solar atmosphere from its surface up to its outermost layer.
The observations of the IRIS spacecraft will be focused on 1% of the Sun’s surface, a close look to understand its changes. The area of the atmosphere that will be observed is the one in which most of the ultraviolet emissions are generated. They reach the Earth as well, influencing its climate. That’s why the IRIS telescope was built for observations int that range of electromagnetic frequencies.
Other solar phenomena such as coronal mass ejections and solar flares are another subject of interest, especially for those who must build spacecraft and satellites. In fact, the charged particles emitted during those phenomena can damage electronic circuits and various instruments, a significant problem. The observations of the IRIS space probe may help us understand the role of the magnetic flux and matter in those phenomena.
The mission of the IRIS spacecraft is expected to last at least two years. Certainly it will improve our knowledge of the Sun’s behavior and this will give us the ability to predict the most damaging phenomena, with the possibility to take some countermeasure to at least limit the damage.