William Taber has worked on nearly every spacecraft project that has left Earth since 1983, including the Voyager, Hubble Space Telescope and Curiosity rover. Taber, the group supervisor for mission design and navigation software at the Jet Propulsion Laboratory in Pasadena, Calif., spoke about the mathematics behind these projects to a packed audience in Oopik Auditorium on Wednesday night.
Taber said his interest in mathematics began after learning how to complete a proof in high school geometry. He described the experience as magical, like he was given a "key to the universe."
"Mathematics is part of my DNA," Taber said. "It's a weapon in our fight against ignorance and uncertainty and when it works, mathematics is the poetry of reason."
Taber most recently worked on the Curiosity rover's Mars landing last August. The event was internationally broadcast and attracted over 1,000 media outlets.
"We accomplished this through a lot of meetings, a lot of money, a lot of custom hardware, a lot of hard work and a lot of math," Taber said.
The first problem that Taber encountered was determining Mars' precise location relative to Earth, which the team was eventually was able to calculate using differential equations, calculus and linear algebra.
The team also needed to determine the time the spacecraft would arrive at the surface of Mars, precise up to one nanosecond. The rover's flight path required perfect timing, since the landing depended on the alignment of Mars and Earth, which only happens about once every 780 days. If the mission was unsuccessful, the next opportunity to launch the rover would be over two years later.
The team considered the effects of gravity, solar pressure, heat and altitude control, using high resolution images and probabilistic analysis to determine Curiosity's safest landing spot within Gale Crater. Taber and his team computed the expected hazard for every pixel on every image, which totaled one million computations per pixel for one million pixels. Using a mathematical trick called the Fast Fourier transform, the team expedited the seemingly time-consuming process and completed the computations in an hour.
Taber advocated investing in solar system research.
"We should study the planets for the fun of it, for the poetry that we get out of it, for the music, the art, the adventure and the knowing," Taber said. "We should be able to sit around the table with our colleagues and families and talk about our knowledge beyond the Earth."
Taber introduced further unanswered questions regarding the possibility of life beyond Earth, suggesting that at one point, both Mars and Jupiter had the ability to sustain life.
Taber said he considers the "family portrait" of the solar system that was taken from Voyager in 1990 the most profound picture of all time.
"Pictures can change how people view the world," Taber said. "We're just one group of human beings scattered around water and land and air."
Taber concluded by reading a segment from Robert Frost's poem "The Star-Splitter," which tells the story of a man who burns down his house for insurance money in order to buy a telescope. Taber gave a quote from the astronomer Carl Sagan about the minuteness of Earth relative to the solar system.
Students and professors interviewed said they enjoyed the lecture.
"It's amazing to see how everything we learn during class can answer some of life's most profound questions," Mackenzie Foley '16 said. Mathematics professor Alex Barnett said the talk was accessible and contained an appropriate combination of mathematics and visual aids.
The lecture, titled "A Flight of Curiosity A Mathematician's Tale," was sponsored by the mathematics department.
