July 11, 2015 – Last night, a crowd of all ages gathered at the Denver Museum of Nature and Science in Denver, Colorado to learn about the New Horizons space probe and its upcoming encounter with Pluto. The sold-out event featured key mission scientists and engineers – all based in Colorado – discussing the first space mission built specifically to study the dwarf planet Pluto.
In fact, this is a very Colorado-centric mission: Alan Stern, the principal investigator, is from Southwest Research Institute (SwRI) in Boulder. Lockheed Martin contributed the RTG Power Supply for the spacecraft. The University of Colorado Boulder contributed the Student Dust Counter and Ball Aerospace the main spectrometers. Former Colorado Senator Mark Udall was instrumental in supporting the mission in its early days, when it was critical. And New Horizons launched on a United Launch Alliance Atlas V rocket on January 19, 2006.
Everyone on the team remembers that day.
“Seventeen years of your career comes down to putting it on that rocket and waiting for it to launch,” said Stern.
The team didn’t have long to wait because New Horizons was the fastest spacecraft ever launched. Everything on the probe was miniaturized. The combined weight of all of the instruments was less than the weight of a single camera on Cassini. This tiny, lightweight spacecraft was then launched on a powerful rocket. An Apollo spacecraft traveled about 25,000 mph and took three days to reach the moon – New Horizons took only nine hours to reach the same distance!
Now, after a voyage of nine and a half years and three billion miles, the New Horizons probe is about to make its closest approach to Pluto on July 14, 2015. Stern set the stage for the encounter:
“We don’t know what we’re going to find when we get there and that’s the best part,” said Stern. “We know almost nothing about it! This is like the great exploration missions of the 1960’s and 70’s. We are writing the textbooks on Pluto.”
Stern knows about great missions – he’s been involved in twenty-six of them, including missions to Mars, Venus and Jupiter – but says nothing comes close to New Horizons.
“Exploring Pluto and the Kuiper Belt is like conducting an archaeological dig into the history of the outer solar system, a place where we can peek into the ancient era of planetary formation,” said Stern.
Also speaking at the event were Fran Bagenal, co-investigator; Joe Peterson, team lead for the Tombaugh Science Operations Center; and Jamey Szalay, the lead student on the Student Dust Counter instrument team.
Bagenal gave a brief history of our knowledge of Pluto and talked about the task of choreographing the Pluto encounter.
“After nine and a half years to reach Pluto, we only have two hours of time in the close fly-by,” said Bagenal.
The team has done multiple dress rehearsals, but with less than five weeks left until the encounter, scientists and engineers are pouring over data to make sure they have the best plan in place. Commands can’t be sent in real-time because it takes data 4.5 hours to reach New Horizons and another 4.5 back to Earth to confirm that an instruction has been executed.
Before the fly-by, the spacecraft will be pre-programmed with a carefully orchestrated route through Pluto and its system of moons. New Horizons will be rotating to take images and to allow its instruments to extract as much data as possible. It will take in so much data, in fact, that it will take sixteen months to transmit all of it back to Earth.
And what does the data look like?
“The downlink data team gets raw data back in 0’s and 1’s,” said Peterson. “We have to assemble it with complex algorithms into images and data files, then calibrate them, and archive them so people 100 years from now will still be able to use the information.”
The New Horizons payload, developed under the direction of SwRI, includes imaging infrared and ultraviolet spectrometers, a multi-color camera, a long-range telescopic camera, two particle spectrometers, a space-dust detector and a radio science experiment.
Ball Aerospace built the Ralph instrument, which is designed to be the “eyes” of the mission. Equipped with a powerful visible imager and an infrared spectrometer, Ralph will take images as New Horizons approaches, flies past, and looks back at Pluto.
The dust counter was designed and built by students at the University of Colorado, Boulder and is the first student-built instrument to ever fly on a NASA planetary mission. Szalay said that he was lucky to be recruited for the mission as a beginning Physics student at the University of Colorado. Now in his final year as a graduate student, he is looking forward to working in the space industry.
“This mission completely transformed my life,” Szalay said.
Szalay explained the Student Dust Counter (SDC) as a very thin, very sensitive instrument located on the front of the spacecraft. As New Horizons rushes through space at 10 miles per second, particles hit the SDC, creating a small dent in the instrument’s material. A human hair is roughly the width of 50 microns and the SDC can measure dust particles that are 1/100th the width of a human hair. Szalay likened the SDC to a football field and said that if the instrument were the size of the field, it could detect a poppy seed that was dropped on the playing field.
Although there are not a lot of particles hurling through space, the SDC registers about one hit per day — and with so many days in space, it gives the team plenty of information to analyze.
The spacecraft itself is protected by a layer of Kevlar because at the speed the probe is traveling, even a particle as small as a grain of rice could do major damage. It’s these damaging particles that the team is hoping to avoid as it travels into the Kuiper Belt.
The hazard avoidance team has been looking at images and data as the spacecraft moves closer to Pluto. Slight trajectory changes could be made if anything dangerous appears during the month leading up to the encounter, but so far, the way looks clear.
The team is not making any guesses about what they’ll find during the Pluto encounter, but expect to be surprised.
After the Pluto flyby, the mission team hopes to select another Kuiper Belt object to travel to and study. With the help of the Hubble Space Telescope, the team has narrowed their selection to two possible objects, but they are in opposite directions from Pluto. If the New Horizons mission is extended by NASA, a decision will need to be made and the spacecraft will arrive at one or the other object in 2019.
And after studying a Kuiper Belt object?
“New Horizons will keep on flying and eventually it will exit the galaxy. Billions of years from now, when our Sun bloats up into a Red Giant, it will expand to consume the Earth,” said Stern. “New Horizons will outlive Earth itself.”