On July 11, NASA scientists will launch into space the highest resolution solar telescope ever to observe the solar corona, the million degree outer solar atmosphere.
But it will only last 10 minutes.
During that ten-minute journey, the High Resolution Coronal Imager (called HI-C) will focus on the center of the sun, where a large sunspot is predicted to be – a prediction based on what the sun looked like 27 days previously, since it takes 27 days for the sun to complete a full rotation. HI-C will fly aboard a Black Brant sounding rocket to be launched from the White Sands Missile Range in New Mexico. Half of its 620 seconds of flight will have it high enough that Earth's atmosphere will not block ultraviolet rays from the sun. By looking at a specific range of UV light, HI-C scientists hope to observe fundamental structures on the sun, as narrow as 100 miles across.
The spatial resolution on HI-C is some five times more detailed than the Atmospheric Imaging Assembly (AIA) instrument on the Solar Dynamics Observatory (SDO), that can resolve structures down to 600 miles and currently sends back some of our most stunning and scientifically useful images of the sun. While AIA can see the entire sun at this resolution, HI-C will focus on an area just one-sixth the width of the sun or 135,000 miles across and while AIA observes the sun in ten different wavelengths, HI-C will observe just one: 193 Angstroms. This wavelength of UV light corresponds to material in the sun at temperatures of 1.5 million Kelvin and that wavelength is typically used to observe material in the corona.
NASA's HI-C will launch on July 11, 2012, to observe the sun's corona in the highest detail ever captured during a 381-second mission. Credit: NASA
"We will start acquiring data at 69 seconds after launch, at a rate of roughly an image a second," says Jonathan Cirtain, a solar scientist at NASA's Marshall Space Flight Center in Huntsville and project scientist for HI-C. "We will be able to look through a secondary H-alpha telescope on the instrument in real time and re-point the main telescope as needed."
In addition to seeing the finest structures yet seen in the sun's corona, the launch of HI-C will serve as a test bed for this high-resolution telescope. Often one improves telescope resolution simply by building bigger mirrors, but this is not possible when constraining a telescope to the size of a sounding rocket, or even a long-term satellite. So HI-C's mirror is only about nine and a half inches across, no bigger than that of AIA. However, the HI-C mirrors, made by a team at Marshall, are some of the finest ever made, says Cirtain. If one could see the surface at an atomic level, it would show no greater valleys or peaks than two atoms in either direction.
"So it's super smooth," says Cirtain.
In addition, the team created a longer focal length – that is, they increased the distance the light travels from its primary mirror to its secondary mirror, another trick to improve resolution – by creating a precise inner maze for the light to travel from mirror to mirror, rather than a simple, shorter straight line.
The Finest Mirrors Ever Made, And Their 10-Minute Mission
By News Staff | July 7th 2012 07:14 PM | Print | E-mail