ESA's Solar Orbiter Has a Cosmic Rendezvous With a Comet's Tail This Week
Last month astronomers discovered that the ESA probe Solar Orbiter would sweep through the tails of C/2019 Y4 (ATLAS).
Researchers revived the sleeping spacecraft, so it could capture important data about comets during the drive-by.
C/2019 Y4 (ATLAS), you might remember, is one of the comets suspected to have broken apart in April.
The European Space Agency's Solar Orbiter is on a mission to kiss the sun. The spacecraft will be the first to study the sun's poles—regions on the star that we know almost nothing about. It's currently flying along an orbit wedged between Venus and Mercury, and is scheduled to make its first close approach to the sun, or perihelion, on June 15. It'll be about 48 million miles from the boiling surface of our parent star.
Researchers had planned to keep the spacecraft's instruments in sleep mode until this approach, but Geraint Jones, a researcher at the UCL Mullard Space Science Laboratory in the U.K., made a serendipitous discovery.
He noticed that the spacecraft would swing directly into the path of a nearby comet's tails. Solar Orbiter is designed to study the sun, but researchers realized that if they booted up the craft in time, its ten instruments could collect valuable data about the comet, called C/2019 Y4 (ATLAS).
As C/2019 Y4 (ATLAS) zoomed closer to the sun earlier this year, astronomers hoped it would be visible from Earth. Unfortunately, the comet fragmented and dimmed in April, dashing the hopes of telescope-tied astronomers.
Scientists have booted up the sleeping spacecraft in order to collect data about the comet. C/2019 Y4 (ATLAS), like other comets, has two different tails: one is an ion tail filled with particles charged by the sun, and the other is a dust tail. The sun-bound spacecraft is currently passing through C/2019 Y4 (ATLAS)'s ion tail and will sweep through its dust tail on June 6.
Astronomers hope that the spacecraft's magnetometer might be able to measure the interaction between the charged ion tail and the solar system's interplanetary magnetic field. A Solar Wind Analyzer attached to the spacecraft may be able to collect particles from the comet's tail.
"With each encounter with a comet, we learn more about these intriguing objects," Jones said in a press release. "If Solar Orbiter detects Comet ATLAS's presence, then we'll learn more about how comets interact with the solar wind, and we can check, for example, whether our expectations of dust tail behaviour agree with our models. All missions that encounter comets provide pieces of the jigsaw puzzle."
This isn't the first time a spacecraft has swung through the wake of a comet. In 20o0, Jones discovered a strange pattern in data gathered by the ESA/NASA Ulysses spacecraft. In total, Ulysses had passed through a total of three cometary trails during its journey around the sun. Each of the encounters—all of which were discovered by Jones, who clearly has a knack for this sort of thing—have revealed new insights into how comets work.
It's been a busy year for Solar Orbiter, which launched on February 10. Scientists briefly paused work on the spacecraft, along with other missions including Mars Express, ExoMars, and the Cluster mission, as COVID-19 spread across Europe. The team has since renewed work in preparation for this month's solar fly-by.
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