At the end of this month, NASA is launching a new mission to space to better understand how energetic particles mingle in the upper reaches of Earth’s atmosphere in what’s known as space weather. And for the first time, the mission won’t rely on a full satellite to gather data from orbit, but on a single scientific instrument that will live on a commercial satellite.
The host probe is SES-14, a satellite built and controlled by Luxembourg-based operator SES. When it launches at the end of January on a European Ariane 5 rocket, SES-14 will eventually climb to an orbit about 22,000 miles above the Earth’s surface, with the NASA instrument positioned toward our planet. From there, the instrument, called GOLD, will gather data about the boundary between Earth’s upper atmosphere and space — a region between 30 and 600 miles up known as the ionosphere, where major space weather events can occur.
What GOLD learns will help scientists better predict how the ionosphere responds to certain types of natural phenomena or events — such as the bombardment of particles streaming from the Sun, tsunamis, or hurricanes. GOLD won’t be alone in learning all this: another NASA mission called ICON will launch a satellite later this year that will sit in a much lower orbit, where it can gather more up-close data on the ionosphere. “They each have their own specific science missions, but the two missions are highly complementary,” Sarah Jones, the mission scientist for GOLD at NASA’s Goddard Space Flight Center, tells The Verge.
One of the biggest things GOLD will study is how the Sun interacts with the ionosphere. For instance, the Sun produces a lot of extreme ultraviolet radiation, which then gets absorbed by the gasses around our planet. That actually helps to shield people from receiving too many harmful doses of radiation. But it also causes the particles in the ionosphere to heat up and give off light — what’s known as airglow.
The Sun also periodically burps up a bunch of energized particles toward Earth, which are events known as coronal mass ejections. “The Sun actually spits off a piece of itself,” says Jones. “It’s plasma with the Sun’s magnetic field embedded within it.” These ejections can cause disturbances in the Earth’s magnetic field. When such geomagnetic storms happen, the particles in the ionosphere are thrown out of whack: not only do they heat up and get energized, but they move upward and expand, changing the density of the upper atmosphere. “If you were to see a picture of the Earth’s atmosphere, it would look like it was kind of breathing in and out,” says Jones.
These events can have a big impact on us here on the surface, as the ionosphere has become a crucial place for many of the technologies we use in our daily lives. Various GPS and communications satellites are located up there, as well as the International Space Station, radio signals used for communicating with ships and planes, and electrical currents that interact with Earth’s power grid. However, major storms in the ionosphere can throw off the orbits of spacecraft and muck up our communications systems, as well as cause power fluctuations.
It all depends on how the ionosphere reacts to the Sun, which is why scientists want to better predict how solar activity affects the upper atmosphere. That’s where GOLD comes in. From above, the instrument will be studying the composition and temperature of the ionosphere in response to the Sun’s actions. “That’s half of the GOLD mission,” says Jones.
The other half is what’s going on down on Earth: tsunamis, hurricanes, and even earthquakes can shake up the ionosphere, causing winds to shift high above the planet. GOLD will be studying how these major events alter the upper atmosphere, with some help from ICON. When ICON launches, it will be flying at about 357 miles above the Earth’s surface, putting it right in the thick of the ionosphere. There, it will measure how the winds from lower altitudes affect the upper portions of the atmosphere. “The key to understanding the upper might very well lie in our ... understanding of the energy that’s coming from below,” Thomas Immel, the principal investigator for ICON at the University of California, Berkeley, tells The Verge.
GOLD’s satellite is set to go up on January 25th, and once it’s in space, it will take a few months for the probe to travel to its final orbit. By the time it does that, ICON will hopefully have launched, too. It’s slated to go up sometime in the first half of this year on top of a small Pegasus rocket, made by Orbital ATK. Together, the two missions will make a unique pairing, both helping to fine tune scientists’ skills of space weather forecasting. “[They’re] built to find the key to making better predictions of the space environment,” says Immel.