The Fastest Moving Artificial Object In History - On A Journey To Pluto PART 3

Read part 1 here.
Read part 2 here.

The Jupiter encounter gave the New Horizons team a plethora of scientific news, but it also provided a valuable dress rehearsal for Pluto. New Horizons team members began filling in the details of the Pluto encounter shortly after the dust settled from the Jupiter fly-by. Programmers will leave gaps in the chain of commands that the spacecraft will use to execute its fly-by. The gaps can be filled in nearer to the Pluto encounter, as more data becomes available.



The challenges at Pluto are unique. Aside from the low light levels at Pluto's orbit, data rate will be reduced by the spacecraft's great distance from home. While light - and radio - time from Jupiter during the encounter was about an hour and half, light time at Pluto is up to four hours. The amount of data the spacecraft can transmit drops significantly.

Fly-by speed at Pluto will be comparable to the speed at which Voyager 2 flew by Triton, a moon that may be similar to Pluto in many ways. Voyager was only able to obtain a handful of medium resolution images of Triton. In contrast, New Horizons will take thousands of images, beginning at 200 days out. Early images will be equivalent in resolution to those taken by the Hubble Space Telescope. Each time the resolution doubles, a new set will be taken and transmitted to Earth. The last few days will see resolutions down to the size of a football field.

The spacecraft will image both Pluto and Charon, and will also scrutinize Nix and Hydra, the two small moons discovered in 2005. The craft will search for other moons and rings. In the case of Jupiter, the rings are fed by debris from its small moons.



In New Horizons' field of vies, Pluto will pass by 134 times as fast as Jupiter did. To avoid smearing of images, the spacecraft will have to slew, or turn, while imaging the planet and its moons. This slewing was utilized at Jupiter with great success. At Pluto, the camera must slew down by another factor of 50. The craft will carry out compositional and infrared studies, as it did for some of the icy satellites at Jupiter.

Pluto has a lot of colour variation and the greatest contrast of any body in the Solar System. Additionally, New Horizons will study Charon up close, making global maps in as much detail as Pluto. The astrophysicist will orient the spacecraft to point toward the Earth as it passes behind Pluto to study the atmosphere. It will then turn again to study Charon within the next hour.

Pluto is a member of a cloud of icy debris at the edge of our Solar System called the Kuiper Belt. After the Pluto mission, New Horizons is designed to fly past at least one other member of the Kuiper Belt. No target has yet been chosen as the area of study lies against a background of many stars and has, in the past, not been search extensively.

The Fastest Moving Artificial Object In History - On A Journey To Pluto PART 2

Read Part 1 here

New Horizons is equipped with a suite of instruments called the Solar Wind Analyzer Around Pluto (SWAP), designed to chart fields of energy and charged particles in the interplanetary environment. Jupiter is surrounded by the largest and most complex magnetic bubble, or magnetosphere, of any planet. With the expectation of the sun, Jupiter's energy is the most powerful source in Earth's sky. In fact, to the naked eye viewed from Earth, Jupiter's magnetosphere would appear twice as far across as the full moon. The human eye cannot see such things, but New Horizons can and this was one of the most important aspects of the Jupiter encounter. The magnetosphere of Jupiter forms a titanic bubble of resistance against the storm of particles that flow constantly from the sun - the solar wind. Trailing behind the planet is the magnetotail, a sort of planetary wake cast by Jupiter across the Sun's magnetic fields.

A representation of Jupiter's magnetosphere and how it interacts with its moons, in particular lo. The lo Plasma Torus is a ring of charged particles emitted by lo's volcanoes that links the moon to Jupiter.
Image: John Spencer (Southwest Research Institute)

Like other New Horizons instruments, SWAP was designed for the subtler environment of Pluto, so its sensitivity had to be reduced in Jupiter's neighbourhood. New Horizons SWAP experiments are similar to equipment flown on earlier missions. The major advantage this time around was the flight path of New Horizons, as it is the first spacecraft to fly down the magnetotail. Additionally, the spacecraft passed through the magnetosphere in a different direction from earlier explorers, giving researchers an invaluable new slice of the complex system to study.

New Horizons confirmed some aspects of earlier theories and models of Jupiter's complicated fields and particles, but shed light on new aspect as well. There were a lot of subtle suprises in the details of how this things works.

One revelation has been how complex the magnetotail is, most models potray it as a column of quiet space - a kind of magnetic backwater - behind the planet. But New Horizons data shows that the region is complicated and interesting. The is no obvious, simple picture. The magnetotail is a highly structured planetary environment and it will take some time to figure it out.

At this moment of writing, New Horizons is continuing down the tail at a relative speed of 10-15 kilometres/second. The tail appears to move back and forth in the solar wind. At a distance of 2000 planetary radii (around 142 million kilometres), the spacecraft is still within the planet's wake.

To see an animation of New Horizons' voyage down the magnetotail, visit the New Horizons website here.

The Fastest Moving Artificial Object In History - On A Journey To Pluto

New Horizons orbiting Jupiter

It's a long way out to Pluto. NASA's New Horizons spacecraft, the fastest-moving artificial object in history, will arrive there nine years after its launch, coasting by the distant world in the summer of 2015. But its speedy voyage would have taken four more years had it not been for a gravity slingshot afforded by Jupiter.

New Horizons' close fly-by past the king of worlds took place on 28 February 2007. The encounter served as far more than a practice run for the upcoming Pluto arrival. Jupiter is a prime candidate for planetary exploration, a window into the early solar nebula. Its weather patterns have lent insight into fluid dynamics, meteorology and theory. Its retinue of 63 moons - including the quartet of giant Galilean Satellites - provides a miniature solar system for study. Several of the Galilean are the size of planets and have surfaces of ice, as does Pluto and its moon Charon.

New Horizons' use of Jupiter's gravity to get to Pluto presented a valuable chance to study Jupiter in new ways. So far, seven spacecraft in total have visited Jupiter, but New Horizons is equipped with scientific instruments that have never before been flown close to the giant planet. In addition to imaging in visible wavelengths, the Pluto explorer can peer at objects in portions of the spectrum not revealed by earlier spacecraft. New Horizons was also able to take movies of phenomena that the earlier Galileo orbiter could not.

The New Horizons encounter was close than any previous fly-by. For example, New Horizons flew three to four times closer to Jupiter than Cassini did on its way to Saturn in 2000.

But, the encounter was not easy to pull off. The first year of flight was a busy one for the Pluto-bound robot. Engineers and scientists deployed and checked instruments. They made vital trajectory corrections to establish an accurate path for the long flight. They used various stars to calibrate the delicate sensors on the craft. In the midst of all the mayhem, scientists had to plan a complex, Jupiter fly-by only sketched out in preliminary plans.

Complicating the encounter was the fact that New Horizons' instruments were designed for a different environment. Sunlight at Jupiter is some 700 times as strong as that at Pluto. Instruments keyed to imaging in low light levels were prone to be overwhelmed by the bright Jovian environment. One strategy the team devised was to target the most important sights on Jupiter when they were at the terminator, the day/night boundary of the planet. Another significant difference between the Jupiter and Pluto encounters is the time available to the spacecraft during the two fly-bys.

Click here and here to read more about New Horizons' project.