But STEREO-A kept going. Its orbital path around the Sun has given it the chance to do what other NASA spacecraft have done: eventually return home.
It came to fruition earlier this month when STEREO-A passed between the Sun and Earth for the first time since its launch in 2006, NASA said. declared. The flyby marked a milestone for the spacecraft and the team that tracked its progress — and a chance for STEREO-A to prove its relevance after nearly two decades. As it passes Earth, STEREO-A will be used to conduct new research on the Sun, with the help of new NASA satellites developed since launch.
“This is a moment for this mission to shine again,” STEREO’s project scientist Lika Guhtagurtha told The Washington Post.
The two STEREO spacecraft were launched in October 2006 with an ambitious mission: to observe the star from two points as they orbited Earth in opposite directions to create a 360-degree view of the Sun. STEREO-A maneuvered in an orbit around the Sun in front of Earth, and STEREO-B began orbiting the Sun in the opposite direction behind Earth.
The difference in perspective is amazing, Guhathagurtha said. Earth-bound instruments can observe only one Earth-facing part of the Sun at a time, while the rest of the rapidly changing solar surface remains hidden. The dual stereo spacecraft, from their offset positions, allowed the scientists catch A 360-degree view of the Sun for the first time, a feat that made Guhatagurtha even more awe-inspiring.
“Seeing the front and back of the sun at the same time – extraordinary,” he said. “We’re on Earth, human beings, and we’re reaching for it.”
The STEREO craft allowed scientists to better study the Sun’s rotating surface and the hazards it emanates. Both craft provided a three-dimensional view of the Sun, acting in the same way that two eyes create depth perception. Coronal mass ejections – A phenomenon in which plumes of plasma and magnetic field are ejected from the Sun’s outer atmosphere at hundreds or thousands of miles per second, threatening the Earth’s electrical grid and satellites and other planets as well as NASA spacecraft. Those images allowed scientists to track the shape, density and speed of coronal mass ejections as they ripple across the solar system.
As Stereo-A and Stereo-B continued in their orbits, they nearby Far side of the Sun in 2014. It’s a testament to how far they’ve traveled, but also a big risk — moving directly behind the Sun could cut communications between the spacecraft and NASA for months.
Both orbiters, several years past their expiration date, were not designed to operate for long periods of time without communication from NASA. While conducting tests in preparation for the downtime, the company lost contact with STEREO-B. NASA regained contact with the spacecraft in 2016 determined A malfunctioning component sent it into an uncontrollable spin, unable to properly orient its antenna or solar panels, and the company abandoned rescue efforts.
Stereo-A, however, emerged unscathed from the far side of the Sun — and began its long journey toward Earth. Earlier this month, the spacecraft passed between Earth and the Sun to within 5 million miles of Earth. According to to NASA.
The spacecraft came close to Earth on time, Guhadagurtha said. When STEREO-A launched 17 years ago, it observed the Sun during solar minimum, the lowest point in the Sun’s 11-year cycle of high and low solar activity. This limited the number of coronal mass ejections and other events that the spacecraft initially observed. This year, STEREO-A’s return coincides with a period of intense solar activity.
Its flyby means it can return to work it once did with its lost sibling. A capable fleet of near-Earth satellites and probes will help STEREO-A reproduce the 3D imaging of the Sun once captured with STEREO-B, the agency said.
STEREO-A will continue to work at the cutting edge of solar physics. Scientists hope to use the new data collected during the spacecraft’s flight for the latest study theory Giant arcs of solar material crossing the Sun’s surface when seen in ultraviolet light – may be optical illusions.
For Guhathagurtha, who started working on Stereo in 1998, Stereo-A’s persistence after such a long journey is heartening.
“It’s like watching your children grow up and do extraordinary things,” Guhadagurtha said. He added that depending on NASA’s budget decisions, STEREO-A’s mission may not be completed. Either way, STEREO-A will continue on its course in another orbit around the Sun.
“They won’t be home,” Guhatagurtha said with a smile. “They go away very quickly.”
