The National Science Foundation’s Green Bank Telescope (GBT), located in Green Bank, West Virginia, played a role in NASA’s Mars 2020 Perseverance rover landing.
The GBT received communications from the rover as it arrived on Mars yesterday and passed these on to NASA’s Jet Propulsion Laboratory (JPL) located in southern California.
The GBT tracked the faint communication signal transmitted by Perseverance at a frequency of just over 400 MHz. As the rover entered the Martian atmosphere the total descent, known as the Entry-Descent-Landing phase (EDL), took about seven minutes.
Referred to as the “seven minutes of terror,” Perseverance slowed down from 12,000 miles-per-hour to just a few feet per second. This rapid change in speed generates a lot of heat, creating a shield of ionized particles around the rover, temporarily obscuring its communication signal to Earth. To reach the surface safely, Perseverance used a heat shield to protect itself during entry, deployed a supersonic parachute to slow down and executed the “skycrane” maneuver to slowly touch the rover down on its wheels.
Will Armentrout, Green Bank Observatory project scientist for Perseverance, recalled, “I remember exactly where I was when NASA landed Curiosity on Mars in 2012, curled up at home with a bag of popcorn and getting ready to start as a physics graduate student the next week. For the 2018 Insight landing, I was a post-doc at Green Bank peeking over the shoulder of another scientist. There’s such a human component to all of these NASA missions, and they have a way of sticking in our memory.”
When asked what he was doing for the 2021 Perseverance landing, Armentrout replied, “Supporting the GBT controls, praying we [saw] that signal.”
Since it took nearly 12 minutes for signals to get from Mars to Earth, Perseverance had already landed before the GBT received the signal that the rover had entered the Martian atmosphere. The Effelsberg telescope in Germany also monitored Perseverance as it landed on Mars.
Green Bank Observatory scientist Toney Minter carefully manages the GBT’s dynamic scheduling system to make time for these lander observations.
“The GBT is in demand — each year we receive three times more requests than we are able to schedule from scientists around the world for observing time,” Minter said.
The mission was also supported onsite by project manager Marty Bloss, data analyst Amber Bonsall, microwave engineer Galen Watts, telescope operator Brandon Moore, and emeritus scientist Frank Ghigo.
As NASA/JPL has shared, while on Mars the Perseverance rover will collect carefully selected and documented rock and sediment samples for a future return to Earth, search for signs of ancient microbial life, characterize the planet’s geology and climate, and pave the way for human exploration beyond the Moon.
This is not the first time that the Green Bank Telescope has supported a NASA mission to Mars. In 2018, the GBT received direct signals from the Mars InSight Lander. This provided backup information to NASA during the critical landing stages of the spacecraft and confirmed its successful descent. The GBT was also used to support the Phoenix landing in 2008.
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