New Horizons Makes Its First Visit to Pluto

spacecraft to pluto

On 14 July 2015, New Horizons made an epic journey through Pluto’s system and returned spectacular images showing an icy world with towering water-ice mountains and vast plains of frozen nitrogen. From concept to launch day – and multiple nearly cancelled attempts along the way – took a difficult 17 years.

How does it work?

Pluto presents an especially difficult target for spacecraft to explore. Multiple missions were proposed before NASA finally agreed to explore Pluto in 2003.

Alan Stern, New Horizons mission’s principal investigator, and his team successfully navigated many roadblocks that would have stopped any other Pluto probe from moving forward. Members of their core group shared personal accounts of its emotional turmoil in Chasing New Horizons book.

New Horizons was the fastest spacecraft ever launched from Earth; at that speed, a flight from New York to Los Angeles would only take nine minutes! Unfortunately, such speed increased distance traveled toward Pluto; engineers used Jupiter’s gravitational pull as an aid to speed up New Horizon’s trajectory toward its target planet.

What’s the plan?

NASA’s New Horizons probe was the first spacecraft to reach Pluto since Clyde Tombaugh discovered it in 1930; NASA’s New Horizons probe broke the silence in 2015 by flying past Pluto’s atmosphere and Charon, its large moon.

Designers of New Horizons had to ensure its avoidance of collision with any of the Kuiper Belt’s numerous comets or other small bodies as it zipped by at 10 miles per second – even something as tiny as a grain of rice could destroy its probe!

Stern first proposed using a lander to study Pluto’s surface, but later revised his plan in favor of an orbiter called Persephone (after his wife in Greek mythology and queen of the underworld) which could follow up on any noteworthy discoveries made by New Horizons while searching for additional KBOs that might exist.

But a Pluto orbiter needs twice the payload mass and fully redundant systems of New Horizons, plus enough fuel to make its entry into Pluto’s orbit – this makes the Persephone concept very expensive to execute.

How long will it take?

NASA scientists working on their Voyager program initially envisioned flybys of Pluto as part of a “Grand Tour” of outer planets; however, upper management pushed back and caused its mission to languish for years.

For its Pluto mission, which requires cameras, radar, and spectrometers to function effectively, spacecraft must include one or more plutonium reactor thermal generators (RTGs). RTGs generate electricity through radioactive decay; once run down they must be replenished with xenon fuel from Earth to continue working efficiently.

After its Pluto-Charon encounter, New Horizons will proceed into the Kuiper Belt – an immense icy debris ring beyond Neptune – where depending on how much fuel remains it may visit and study other objects within this vast space ring. A concept presented by Howett called Persephone would enable enough fuel storage capacity for such rendezvous attempts; then orbit these frozen worlds for three years collecting data about them and their moons.

What will we learn?

Since 2005, the New Horizons probe – roughly the size of a grand piano – has quietly navigated space. Dodging cosmic debris at three billion miles per hour, using Jupiter’s gravity as a slingshot and firing thruster burns to stay on course, it remained on course and headed toward Pluto.

This mission has produced remarkable images of Pluto and its moons. For instance, in Sputnik Planitia there is an astonishing patch of smooth ice with polygonal cells beneath its surface that reveal convection churning away underneath – unlike any glacier scientists have encountered on Earth!

New Horizons also discovered an unusual collection of mountains near Sputnik Planitia with pitted summits that may be ice volcanoes spewing out icy “lava,” rather than fiery magma. Another possibility could be an ocean of liquid nitrogen lurking beneath Sputnik, pushing its mass toward its equator and helping to shift landscape features over time.

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