NASA's New Horizons probe set to capture best images of Pluto in flyby
It's been a long journey — 9½ years, and just over 4.7 billion kilometres — to the farthest depths of our solar system, and like any tourist, this one is bringing a camera for our first close-up view of Pluto.
On Tuesday, NASA's aptly named New Horizons spacecraft will reach its closest distance from Pluto with a 30-minute flyby of the difficult-to-see dwarf planet.
At its closest, about 12,500 kilometres away from Pluto, New Horizons is expected to produce never before seen clear, colour images of the icy object, and should reveal parts of our universe previously left only to our imaginations.
"Every bit of this is a huge success," says planetary scientist Lindy Elkins-Tanton, director of the School of Earth and Space Exploration at Arizona State University. "This is the kind of body we really haven't seen before ... a reminder of what true exploration is like."
Humans have sent probes to all of our planets, but never to Pluto — leaving its five confirmed moons, including Charon, never closely observed in any depth.
The goal of this NASA mission is "to make the first close-up study of Pluto and its moons and other icy worlds in the distant Kuiper Belt," according to its website.
It will be a "stepping stone in our level of understanding," Elkins-Tanton said.
In an April statement, NASA called the upcoming flyby an "unprecedented" moment.
"We've never studied Pluto up close and personal," wrote John Grunsfeld, astronaut and associate administrator of the NASA Science Mission Directorate.
Piano-sized probe
"What is it about our solar system that makes it habitable for life?" is the question behind this project and all other space explorations, Elkins-Tanton says. "Science gives us a way to answer our questions. We know almost nothing" about the relative vastness of space.
When NASA first launched New Horizons in January 2006, scientists were only aware of Pluto and its largest moon, Charon. Since then, they have discovered four new moons and they are thinking more may be discovered as the spacecraft gets closer.
New Horizons was designed and put together at the Johns Hopkins University Applied Physics Laboratory in Maryland, receiving assistance from other groups such as the Southwest Research Institute and many countries around the world.
Weighing 478 kilograms, the piano-sized probe, as NASA calls it, needs less power than two 100-watt light bulbs for this long Pluto mission as it has been designed to work off of a radioisotope thermoelectric generator that converts radioactive material into electricity.
The onboard camera weighs 8.8 kilograms, and provides high-resolution images. NASA describes it as "essentially a digital camera with a large telephoto telescope" built to withstand frigid temperatures on the outer edges of our solar system.
It is already capturing higher-quality images than the Hubble space telescope has ever taken of Pluto, NASA asserts.
Its instruments are designed to receive faint radio signals from Earth, with round-trip transmissions taking nine hours to complete from Pluto — which is currently more than 30 times Earth's distance from the Sun.
Slingshot manoeuvre
The trek across the solar system wasn't quick or direct.
The spacecraft navigates using small thrusters and onboard gyros, star trackers and sun sensors. In an emergency, there are electronic backup devices.
And while New Horizons was the fastest spacecraft ever to leave Earth, bolting away at a velocity of 58,536 km/h — 70 times faster than a jet airliner — it needed a carefully-orchestrated boost from Jupiter to make its way to Pluto.
Thanks to the giant planet's incredible mass, the spacecraft was sent shooting through its system at more than 80,000 km/h in a kind of gravitational slingshot that helped accelerate the probe. Along the way, it snapped high-resolution photographs of the largest planet in our solar system along with its more than 60 moons.
Following the gravity assist from Jupiter, NASA's team began checking in on the spacecraft to prepare it for its visit to Pluto. They also began scoping out Kuiper Belt objects (there are tens of thousands) for potential targets to study after the Pluto phase, which is a future project pending approval.
When New Horizons finally reaches its closest point to Pluto, about 12,500 kilometres away, and Charon, about 28,800 kilometres away, it will begin searching for ultraviolet emissions to map out these objects.
It will also measure methane levels and conduct spectral maps to try to determine surface compositions, locations and temperatures of the materials on these two surfaces.
But after travelling all that way for so many years, half an hour is only how long the probe will be closest to Pluto. That's when the best close-up photos of the planet will be taken, providing a tiny yet detailed glimpse into what is now called a dwarf planet, first discovered in 1930.
"It's like someone hands you an ice cream cone and lets you have a taste and takes it away," is the way Elkins-Tanton describes the short stay near the object.
She says scientists hope to discover details on Pluto's surface features beyond impact craters, as well as evidence about its atmosphere and any hints of ancient activity, such as icy eruptions similar to a comet.
"One of the miracles of space engineering" is knowing that a robot is going to work for years without failure, Elkins-Tanton says, alongside what she calls the hundreds of "technological super-people" who are operating each of the seven instruments related to this project.
Transmitting all of this information from so far away may be the greatest feat about this mission. "We're already getting better images of Pluto than ever before," she adds.
