Cabrillo astronomy professor helps land Hayabusa spacecraft
Richard Nolthenius’ love affair with the night sky began when he was a child. “The sky doesn’t try to impress you,” he remembers realizing at age 10. “It doesn’t try to posture to be this, that or the other. It’s just so natural and so unaffected by us—and pure in some way.”
That year, 1963, a solar eclipse would solidify his dedication to studying the mysteries of the heavens. “There was a solar eclipse and they predicted exactly what it would look like when it was still two weeks in the future,” Nolthenius recalls. “I saw the eclipse and I said ‘Oh my God, it’s happening exactly the way they predicted.’ At the time, people were this chaotic, malevolent thing and I was hungering for something rational and understandable. And astronomy was also great because it was something I could do by myself at night since everyone else was asleep.”
Fast-forward to today: Nolthenius is a professor in Cabrillo College’s astronomy department, which he describes as a “one-man department.” He is also involved in the exciting Hayabusa space mission—an unmanned spacecraft mission led by Japanese Aerospace Exploration Agency (JAXA). The first mission since the moon in which astronomers hope to return samples, Hayabusa aimed to bring samples from the near-asteroid Itokawa back to Earth.
After traveling in space for seven years, the Hayabusa came home on June 13, welcomed by the whole team—including Nolthenius, who traveled to Australia last week to help bring it safely back.
But the work doesn’t stop with a safe landing: through the samples, the astronomers hope to answer some questions about the solar system—mainly about the nature and potentials of asteroids. Jupiter, which is two and a half times more massive than all the other planets put together, affects the orbits of planet-sized asteroids that form between Mars and Jupiter. Their orbits severely migrate, until some smash into each other, leaving behind fragments that are the asteroids we see today.
“And if that happened after the asteroids were large enough to actually become sort of micro planets, then you’d expect gravity would make the heavy stuff go to the middle and the light stuff would float to the top and so the pieces would have different chemical signatures that would reflect different places within the asteroid where they originated from,” says Nolthenius. “We only have indirect means of trying to decide what that stuff is, but by sampling different asteroids we hope to see better how that fractionation happens.”
Nolthenius’ team consists of Chief Scientist Dr. Peter Jenniskens of NASA, Professor Christopher Kitting of CSU East Bay, and Dr. Julie Bellerose. The team’s mission is to gather spectrophotometry data of the spacecraft’s reentry while it is in the upper atmosphere.
Photometry is the science of measuring precisely the amount of light that a star or a planet is giving off. Spectrophotometry is measuring precisely the amount of light, as well as its wavelength and color. When something hits the upper atmosphere, it causes the air to ionize, which is the process of an electron getting knocked off and then coming back in and bouncing down through the levels, giving off light each time. Essentially, the ionized air will emit energy that glows like a fluorescent light, which varies at different wavelengths. Certain wavelengths, such as oxygen at one line, are near infrared.
Nolthenius’ job will be particularly challenging. Tasked with doing a high-resolution spectroscopy, he will have to aim the lens not where the spacecraft is, but where it is going to be. “We want to get a record of the oxygen line—there will be a fair amount of oxygen ionization going on in the atmosphere,” he explains. “So I need to be able to point exactly 27.2 degrees away in the right direction from the spacecraft. My goal then is just to hold it and keep that centered as it moves across the sky and then just trust that the spectrum is showing up in the main camera.”
The job is the type of adventure his 10-year-old, star gazing self could have only dreamed of. “We’re going to be getting in a four-wheel drive vehicle and heading out into the [Australian] outback and we’ve got to be self-sustained and be able to take care of ourselves if things unexpected happen, and we’ve got to make sure our equipment works no matter what.
“It’s stressful,” he adds, “but it’s an adventure.”