STARKVILLE — An artificial star will one day circle the Earth, helping astronomers understand how bright stars really are, with help from a Mississippi State University researcher.
Angelle Tanner, an MSU associate professor in the Department of Physics and Astronomy, is leading the science portion of a collaborative $19.5 million NASA Space Mission known as “Landolt,” a Wednesday MSU press release said. Tanner is managing a $300,000 sub-grant for the satellite’s development, which will use lasers to help astronomers more accurately measure stars’ brightness.
“Whenever you look at stuff in the sky, you have to compare how bright they are compared to each other,” Tanner told The Dispatch Friday.
“So if you take an image of a star with nothing else in it, you don’t know how bright it is compared to the stars around it, unless you have something to compare it to. And that keeps getting built up and up and up, and you can compare the brightness of stars to the brightness of galaxies and the brightness of supernova.”
Tanner said past astronomers have measured the brightness of stars from the ground and through Earth’s atmosphere, which creates distortions in starlight.
One such astronomer, Tanner said, was Louisiana State University professor Arlo Landolt. She named the project after Landolt, since he was responsible for classifying a group of “standard stars” to compare other stars with as a point of reference for brightness.
Despite her admiration for Landolt, Tanner said, the satellite will help to overcome the issues he would have run into with atmospheric distortion.
“When Arlo would observe the stars from the ground, he would have to deal with the fact that the stars are twinkling,” Tanner said. “And that is due to the Earth’s atmosphere.”
By building a satellite less than a meter in size, equipped with four harmless lasers, Tanner said, scientists can know exactly how many photons of light those lasers emit before they leave the ground. After the satellite is launched 22,000 miles above the Earth, astronomers can use telescopes to measure the number of photons it is emitting through the atmosphere.
The satellite will provide scientists with a clear point of reference for atmospheric distortions, she said, making measurements of brightness for stars and other celestial bodies accurate in a way they have never been before.
“We will know exactly how many photons are coming out of that laser,” Tanner said. “Then they’re going to shoot the laser down through the atmosphere. And since we know how many photons are coming from the laser — because we … designed and built the laser and measured it before we set it up — then we’re going to observe that laser next to one of our special Landolt stars. And we’ll be able to use that laser as a ‘measuring stick’ to measure how bright the star is.”
Once Landolt stars have their brightness accurately measured, Tanner said, they can then be compared to other celestial bodies. From there, she said, applications grow more broad, as a more accurate reading on the brightness of stars could even help with research on the rate of expansion of the universe.
Tanner said she originally joined the NASA project thanks to a graduate school connection with George Mason University Associate Professor of Physics and Astronomy Peter Plavchan. While Tanner and MSU students will be working on the scientific side of the project, Plavchan and others at George Mason will be taking on the engineering work and construction.
“This is what is considered an infrastructure mission for NASA, supporting the science in a way that we’ve known we needed to do, but with a transformative change in how we do it,” Plavchan explained in a Monday press release from George Mason University.
Once the satellite is built, Tanner said, it will be attached to a NASA rocket and launched into a geocentric orbit. She anticipates the launch will happen in about four years. Once the satellite is functional, she said, the lasers will not be visible to the naked eye, but they should be visible through a telescope for those who are interested.
“We also want the public — meaning the astronomy public — to use it,” Tanner said. “It’s going to be up there shining its lasers no matter what. So we want the general public, not just team members, to use it as much as possible.”
Tanner said there are other projects working toward similar goals, which may lead to further discoveries in the future.
“These cubesats, a lot of them are designed to be the beginning of a bigger effort,” Tanner said. “Before we spend a billion dollars building a flagship mission that does this, why don’t we spend $20 million for a little test flight.”
Tanner said Landolt is part of the NASA Astrophysics Pioneers program. For more on the Landolt Space Mission, visit landolt.gmu.edu/. For more on the Pioneers Program, visit science.nasa.gov/astrophysics/programs/astrophysics-pioneers/.
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Quality, in-depth journalism is essential to a healthy community. The Dispatch brings you the most complete reporting and insightful commentary in the Golden Triangle, but we need your help to continue our efforts. In the past week, our reporters have posted 33 articles to cdispatch.com. Please consider subscribing to our website for only $2.30 per week to help support local journalism and our community.
