The last time scientists had a good look at half of the Earth in far ultraviolet light was in 1972, when astronaut John Young took some photos with a special camera during the spare time of the Apollo 16 mission to the Moon. Since then, heliophysicists and other scientists interested in the complex interaction between Earth’s upper atmosphere and outer space have suffered from a lack of data.
That should finally change later this year, after two NASA-sponsored satellites begin to collect data about the composition and temperature of the ionosphere, which ranges from a height of about 60km above Earth to more than 1,000km. Scientists used to think that solar radiation dominated Earth’s very strong atmosphere at this altitude, but in the last decade they have begun to understand that atmospheric weather can also change conditions. top.
“We really want to be able to tease out the effects from the Sun above and the Earth below,” said Sarah Jones, a mission scientist with the GOLD (Small-Scale Observations of the Limb and Disk) mission set to launched. later this month. She and other mission scientists spoke this week during a NASA conference. “The ionosphere is a very dynamic place.”
The microwave-sized GOLD mission will be launched as a component on a very large communications satellite, SES-14. This marks the first time that NASA has used this commercial route, known as a hosted payload, for one of its science missions. It does so to help keep costs down. According to NASA, the cost for this mission is $55 million.
The satellite has already been delivered to Kourou, in French Guiana, for a launch scheduled for January 25 on an Ariane 5 rocket. After reaching the launch pad, the spacecraft will take a few months to reach the atmosphere at 35,000km above Earth. From there you will have a great view of the Western Hemisphere of the Earth.
GOLD’s main scientific instrument is an ultraviolet imaging spectrometer, which will take pictures of the entire disk of the Earth in ultraviolet light and then break it down by wavelength. Analysis of each wavelength will provide information about the temperature, density, and composition of the ionosphere at that time. The entire disk of the Earth can be imaged every 30 seconds, providing continuous views of how the upper atmosphere changes over time.
Currently, the models available to describe the behavior of the ionosphere collapse after less than 24 hours, Richard Eastes, the main investigator of the mission. Previous missions have only observed a small portion of the ionosphere, or only been able to observe a larger area for a short period of time. GOLD will provide a continuous data stream across the entire world.
A second satellite
The nature of the ionosphere is not only an academic question. Charged particles, such as ions and electrons, can block radio wave signals that propagate through the upper atmosphere from one part of the Earth to another. In particular, dense bubbles of charged gas rise above the equator and erupt at random intervals. A better understanding of the ionosphere and modeling of its behavior should improve the communication systems of the aviation and marine industries, as well as the military.
After its shuttle to geostationary orbit, and subsequent payloads, scientists expect to begin receiving data from GOLD around October. At that time it should be paired with another mission, ICON, also dedicated to studying the ionosphere. This second NASA mission, a small, dedicated satellite, will travel through the ionosphere itself in low-Earth orbit making indoor observations.
Carrying an interferometer and other instruments, ICON will complement the GOLD mission by providing better-resolution measurements of large phenomena observed by satellites in the geostationary sky. ICON should be launched later this year with an initial two-year mission. By the early 2020s, then, space scientists should have a better understanding of Earth’s end—its interface with the rest of the world.
Image courtesy of NASA