July 14, 2015 – In 1930, an object smaller than our moon was discovered, labeled the ninth planet from the sun, and named Pluto at the suggestion of 11-year-old British girl Venetia Burney. The name was adopted because it was thought to be fitting as Pluto is the Roman God of the Underworld who is able to make himself invisible.
Invisible no longer.
Pluto, recently recategorized as a dwarf planet, is now visible thanks to the New Horizons space probe, which reached its closest approach to Pluto on its historic flyby this morning after a nine-year, three billion mile journey.
Aboard the spacecraft are seven scientific instruments, including one designed, built and operated by University of Colorado (CU) Boulder students. This instrument, the Venetia Burney Student Dust Counter (SDC), is named after the girl that gave Pluto its name, and is the first instrument on a NASA planetary mission to be designed, built and operated entirely by students.
“We’ve known about Pluto’s existence since 1930 and we’ve never been able to get close to it, never had great pictures,” said Chelsey Krug, a current Laboratory for Atmospheric and Space Physics (LASP) researcher who worked on the dust counter project as a graduate student at CU Boulder. “We’re finally getting to this item that we’ve never been able to explore before.”
While most of the instruments have been hibernating, waiting for the probe’s encounter with Pluto, the SDC has been continuously measuring the density and distribution of space dust particles on the its journey across the solar system beginning mere months after its launch in 2006.
The dust counter, about the size of a briefcase, is situated on the front of the grand piano-sized spacecraft. It works by collecting data from a sensor that records an electric signal when hit by a dust particle. The instrument can detect the size of the particle based on this signal, as well as its location along the probe’s trajectory.
This unprecedented data will help to improve models of dust in the outer solar system, which have been mostly theoretical to this point. By mapping our solar system’s dust, scientists will be able to compare and contrast it with space dust in other solar systems, which could help in the search for Earth-like planets.
“Dust particles are the building blocks of all planetary objects,” said Mihaly Horanyi, LASP researcher and Principal Investigator for the SDC project. “Understanding how they are produced, destroyed and transported provides important and unique clues about the history, evolution, and current workings of our solar system.”
The SDC is already the farthest traveled dust counter ever, having broken that mark in October 2010, and will reach a distance of more than double the next farthest dust counter in the near future.
Originally planned to shut down to save power when the other instruments awakened from their slumber to start monitoring the Pluto system, NASA decided that there was enough power to keep the dust counter on. This data could help to unlock clues about meteoroid collisions on the dwarf plant and its moons, as well as the possibility of invisible rings orbiting Pluto.
Several of the students involved in the project credit it with helping them develop the skills necessary to launch a career in space science.
“It’s one thing to graduate from school knowing in theory how things work, but having actually done it makes you much more valuable,” said Beth Cervelli, a current LASP spacecraft programmer who worked on the dust counter project as an undergraduate student at CU Boulder.
The students were held to high standards, and even faced panels of NASA scientists for questioning.
“They would ask the same types of questions that they would ask professional engineers, and they were asking them to us students,” said Krug. “It was up to us to have the answer.”
Cervelli is grateful for her involvement in the project because it helped her discover what she wanted to do for a career. After working on the software for the dust counter (which she calls “the brain of the instrument”), she took a job with LASP working on software for other space science instruments.
“I’m extremely grateful that I was in the right place and the right time to be involved in it,” she said.
Now that New Horizons has passed Pluto, the other six instruments will turn off again as the probe continues on its path further into the Kuiper Belt, the outer region of our solar system, turning on only if the spacecraft gets close enough to other large objects. But the SDC will stay on, continuing to collect data on space dust particles as long as it can.
“We believe we have enough power to go through 2035 and perhaps later,” said Fran Bagenal, Co-Investigator on the New Horizons mission, and LASP researcher. The probe’s generator runs on decaying plutonium, similar to Voyager 1, the farthest traveled spacecraft from Earth, which is still operating more than 37 years after its launch.
Entering the Kuiper Belt is exciting for those involved in the dust counter project because there will be more dust to measure, but the debris-filled region of our solar system could also pose problems for the probe. Objects as small as a grain of rice could severely damage the spacecraft due to its high speed—over 30,000 miles per hour. (New Horizons set the record for the highest launch speed of a human-made object from Earth at over 36,000 miles per hour. It also received a gravity assist from Jupiter which shaved nearly three years off the mission time.)
In addition to the science equipment, New Horizons is also carrying a variety of cultural artifacts including an American flag, Florida and Maryland state quarters, a CD containing the names of over 400,000 members of the general public who signed up to “travel” with the spacecraft back in 2005, and a small container of Clyde Tombaugh’s ashes. Tombaugh discovered Pluto in 1930, and his ashes will be the first human remains to exit our solar system.
The students and faculty advisors who worked on the SDC look back on the experience with fondness, but also forward to the science that their data will enable.
“The team kind of became a family as we were working on it,” said Krug. “We all went down to the launch together. It kept getting delayed, so our anticipation was building. When it finally went off I think several of us had tears in our eyes, just because it had been so much hard work.”
“They [the students] have moved on to have families and kids and busy lives, but I know that all of them will closely follow the encounter and remember their contributions with tremendous pride,” said Horanyi in a university press release. “The encounter is a landmark event along the way to explore the outskirts of the solar system, even beyond Pluto, for possibly decades to come.”