New Horizons Pluto Flyby : Patience, Planning and a $700 million Portrait




Pluto, as seen by the New Horizons


In the culmination of a mission involving 25 years of planning, $700 million and countless hours of effort, NASA’s New Horizons spacecraft zoomed past Pluto and its five (or more, according to this new paper) moons at 5:19 pm IST on July 14th, 2015.


This op-ed by astronomer Jay Pasachoff details why astronomers all over the world will be eagerly waiting for the data that New Horizons collects and sends back. They’ll have to wait for quite some time though – 16 months to be precise – because data can only be transferred to Earth at a rate of 1 kilobit/second. The reason why New Horizons is transmitting at a rate 50 times worse than dial-up modems in the ‘90s is explained in detail here.


For those less astronomically inclined, if the Google Doodle didn’t make you sit up and pay attention, here’s a list detailing why this mission is so important to our understanding of the solar system, and interestingly, Earth.


For starters, we don’t actually know what Pluto looks like – we didn’t even know its exact size until a few days ago (about 1473 miles in diameter, give or take 6 miles). NASA’s Hubble telescope – which can capture images of galaxies light-years away –  doesn’t have a resolution small enough to capture photographs of Pluto that would look better than blobs of light. The highest resolution images obtained by LORRI, New Horizon’s highest resolution camera (at 5 microradians) will give us detailed topographical images, similar to satellite images of Earth showing mountains and ice caps. Here’s a great gif contrasting the quality of the latest New Horizons image with previous images taken by Hubble.


The flyby also posed a technological challenge on a scale usually only encountered in science fiction. Seeing as it took 9 years to cover the 3 billion miles between Earth and Pluto (the mission used the gravitational pull of Jupiter as a slingshot to shorten its trip by 5 years), the craft is built with technology that is a decade old, and follows a trajectory that was calculated almost 10 years ago. The mission is run on automated command sequences, so it required years of careful planning to position the craft at the precise time and location to be able to shoot the most mysterious planet of our solar system and its subsystem of moons. Any mistakes and NASA could have ended up with a shot of empty space or worse, a collision.


Because the craft is travelling at a speed of 31,000 mph and can’t slow down, the flyby was over in an interval of 100 seconds. Precise calculations were needed to position the craft in an incredibly small window of 100 m by 50 m. These calculations had to take into account the effects of gravitational pull of the sun and the planets, the effect of the thrusters and even the small pressure with which sunlight hits the spacecraft. These calculations then had to be rigorously verified to avoid accidents like the 1999 mix-up between imperial and metric units that tore apart the NASA’s Mars Climate Orbiter mission. With so many variables and so little room for error, researchers at NASA were understandably jubilant as the spacecraft finally re-established contact after its flyby.


For most of its journey, the spacecraft has been asleep, drawing power equivalent to a few lightbulbs from the chunk of plutonium that acts as the spacecraft’s battery. It was awakened for brief periods of time to run tests and confirm functionality. One such instance was when the New Horizons team used the flyby past Jupiter in 2007 to test the instruments on the spacecraft as well as its flyby capabilities. It was finally awakened in December 2014 in preparation for its Pluto approach.


Now that New Horizons has reached Pluto, NASA expects its momentum to carry it out to the Kuiper Belt (a ring of comets and asteroids surrounding our solar system), where it will be used to study Kuiper Belt Objects.


This flyby is made even more significant by the fact that none of us alive today are going to see anything of this magnitude ever again. As Dennis Overbye says in a New York Times column, “None of us alive today will see a new planet up close for the first time again.” Due to spending cuts in NASA’s planetary exploration budget, the only NASA probes slated to be sent out in the near future are ORISIS-REx and a mission to Jupiter’s moon Europa. ORISIS-REx will be launched next year to collect samples from an asteroid, and won’t be back till 2023. The latter mission isn’t scheduled to be launch until 2025, at the earliest.


If you need any more reasons to be excited or impressed by the mission, this is a good way to remind ourselves of our position in the universe, how vast our corner of space is and how absurdly tiny our whole collective existence is by comparison.

Have any more questions? The New Horizons team did (is doing, at the time of writing) an Ask Me Anything on Reddit.


This article is a part of the Science Diet series produced by the Immerse team at T5E. Science Diet aims to bring science and technology bites from around the world to our scitech-savvy audience. Check out the rest of the articles in Science Diet here.


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