Imagine a spacecraft with no crew entering a planet’s atmosphere at over 12,500 mph having to come to stop in seven minutes — and operating in temperatures of up to 2,370 degrees Fahrenheit.
This is just a glimpse into what it takes to land on Mars.
When the stakes are this high, even the smallest detail can make or break a mission.
That’s why a sensor the size of one grain of rice developed by a NASA-sponsored team led by SMU scientists carries more weight in our missions to Mars than you might think (metaphorically speaking).
By capturing critical measurements — and doing so quickly — the tiny device will help improve our odds of landing on Mars and other planets successfully. The sensor packs this punch despite being up to 250 times smaller than the tool most commonly used to measure velocity on a spacecraft.
And as one of the creators of the device, Volkan Ötügen, notes on the importance of managing weight on a spacecraft: Every single gram counts.
By creating these smaller devices for Mars missions, researchers say that there’s more room for fuel and other critical supplies — and also for samples taken from the red planet. Improving our understanding of Mars through these remotely operated missions then helps scientists reduce risks for future human exploration.
But humans have only been exploring space for a little over 60 years. For some perspective, we have been exploring Earth for hundreds of thousands of years, and there’s quite a bit we don’t fully understand yet.
So, understandably, we still have a lot to learn in space.
As it stands today, NASA reports that only 40% of missions to Mars have actually landed on the planet successfully.
And for each and every one of these missions to even get off the ground, just about a million things need to go right.
You need the right team, the right funding, the right equipment and the right timing. But one other key ingredient — one that’s hard to measure — is imagination.
No matter how many technological advances we make, our curiosity and imagination are often an equally important part of solving big — or in this case, really, really small — problems.
“My sense is that space travel unleashes all kinds of imagination,” said Ötügen, an SMU senior associate dean of the Bobby B. Lyle School of Engineering and professor of mechanical engineering.
“Exploring the universe — that’s why we became engineers and scientists, right? The curiosity. I want to know more. I know I can’t know everything. Obviously. There may be things that are unknowable by the human mind, but there’s so much more to explore [about] how nature works … that excites me.”
There are some key, basic questions that help guide a spacecraft entering a planet: Where is it? How fast is it going? And, which direction is it going in?
The question of speed, Ötügen said, is particularly important.
The device the team developed and tested in a study published in AAIA Journal in December 2021 uses LiDAR-based sensors (LiDAR stands for “light detection and ranging”), and a phenomenon known as “whispering gallery mode” to capture precise measurements.
Legend has it that whispering gallery mode was discovered by English physicist, mathematician and 1904 Nobel Prize winner Lord Rayleigh at St. Paul’s Cathedral dome in London.
In this big dome with round walls, Rayleigh realized that if he stood by the wall and whispered to someone in the middle of the dome, they could not hear him. But if he whispered to someone near the wall on the opposite side, they could.
This is because the sound waves bounce off the curved wall of the dome, making their way around it. And the same thing happens to light waves.
Through this same phenomenon, light fed into the device developed by Ötügen’s team travels around the cavity of the device millions of times. By recording shifts in the light’s frequency as the spacecraft travels, the device allows scientists to measure velocity and acceleration with very high precision.
“Although there are still a lot of engineering challenges to make it into a reliable product, scientifically, this is very promising,” said Lan Yang, a professor at Washington University in St. Louis who has been studying this type of device her entire career.
The device, she said, could mark a huge step forward. “Whispering gallery mode is extremely sensitive to light frequency … It is one of the best ways calibrate frequency resolution,” said Yang, a professor of electrical and systems engineering.
This high precision could be one of the small details that brings us one step closer to more successful missions — a detail which arose, to some extent, from asking curious, imaginative questions. Some are still being asked today, and some date back to over a hundred years ago, in St. Paul’s Cathedral (as legend has it, of course).
Jessica Rodriguez reports on science for The Dallas Morning News as part of a fellowship with the American Association for the Advancement of Science.
