Seeker Archives

Pluto's Tiny Moons Spied by Incoming NASA Probe

A NASA spacecraft speeding toward an epic flyby of Pluto on July 14 has beamed home its first good looks at two moons of the dwarf planet.

A NASA spacecraft speeding toward an epic flyby of Pluto on July 14 has beamed home its first good looks at two moons of the dwarf planet.

The New Horizons probe captured images of Nix and Hydra, two of Pluto's five known satellites, from Jan. 27 through Feb. 8, at distances ranging from 125 million miles to 115 million miles (201 million to 186 million kilometers), NASA officials said. The photos have been spliced together to create a short movie showing Nix and Hydra circling Pluto.

ANALYSIS: Pluto and Moon Charon May Share Same Atmosphere NASA released the new footage Wednesday (Feb. 18), 85 years to the day after American astronomer Clyde Tombaugh discovered Pluto at the Lowell Observatory in Flagstaff, Arizona. [Photos from NASA's New Horizons Pluto Probe]

"It's thrilling to watch the details of the Pluto system emerge as we close the distance to the spacecraft's July 14 encounter," New Horizons science team member John Spencer, of the Southwest Research Institute in Boulder, Colorado, said in a statement. "This first good view of Nix and Hydra marks another major milestone, and a perfect way to celebrate the anniversary of Pluto's discovery."

New Horizons team members discovered Nix and Hydra in 2005 using NASA's Hubble Space Telescope. Scientists think both moons are between 25 miles and 95 miles (40 to 153 km) wide; New Horizons should nail down their sizes when it zooms through the Pluto system this summer.

NEWS: New Horizons Spies Pluto's Tiny Moon Hydra

Hydra is Pluto's outermost known moon and circles the dwarf planet every 38 days, at a distance of about 40,200 miles (64,700 km). Nix lies 30,260 miles (48,700 km) from Pluto and completes one orbit every 25 days.

Two other Pluto moons, Styx and Kerberos, are smaller than Nix and Hydra, and are too faint to show up in the latest New Horizons images, NASA officials said. The dwarf planet's other known moon, Charon, blends into Pluto in the photos, creating a fuzzy white blob. (Charon is about 750 miles, or 1,207 km, in diameter - about half as wide as Pluto itself.)

The new photos were captured by New Horizons' Long-Range Reconnaissance Imager (LORRI), to help improve team members' understanding of the orbits of Nix and Hydra. The right-hand images have been processed to remove the Pluto-Charon glare and that of background stars, making Nix and Hydra easier to see, NASA officials said.

The streak extending to the right of Pluto and Charon is a result of overexposure, they added. (LORRI took the photos in a special mode that sacrifices resolution to boost sensitivity.)

ANALYSIS: Can We Call Pluto and Charon a 'Binary Planet' Yet?

The $700 million New Horizons mission launched in January 2006, tasked with lifting the veil on faraway, mysterious Pluto. On July 14, New Horizons will come within 8,500 miles (13,600 km) of the dwarf planet's surface.

That highly anticipated flyby may not mark the end of the probe's deep-space work. Mission team members want to send New Horizons on to explore a second body in the Kuiper Belt, the ring of icy objects beyond Neptune that Pluto calls home. If NASA funds this extended mission, the additional flyby would take place in 2019.

More from SPACE.com:

Pluto's Moons Nix and Hydra Spotted By NASA Probe | Video Photos of Pluto and Its Moons Pluto / Charon Wobbly Dance Proves It's A Double Planet | Video Originally published on Space.com. Copyright 2015 SPACE.com, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

NASA's New Horizons probe captured these views of the Pluto moons Nix (yellow diamond) and Hydra (orange diamond) between Jan. 27 and Feb. 8, 2015. Pluto and its largest moon, Charon, are the fuzzy white blob in the images' center.

On July 1, 2004, NASA's Cassini spacecraft arrived at Saturn orbit seven years after launch from Earth in 1997. Over ten years after arriving at the majestic gas giant, Cassini has profoundly transformed our understanding of the planet's dynamic atmosphere, rings and moons. Now the mission is entering the final stages of its prolific Saturnian odyssey and mission planners hope to use what fuel remains on board for a series of daring "proximal orbits"

through

the ring plane in 2016; a final phase called the "Cassini Grand Finale."

ANALYSIS: Cassini Grand Finale: Saturn Mission's Daring End

The science that Cassini has made since orbital insertion has been nothing short of mind blowing, so let's just take a small sample of key discoveries and stunning observations as featured on Discovery News from the past 12 months as Cassini sailed through its 10th year of Saturnian exploration and toward the history books.

The Hexagon etched into Saturn's upper atmosphere in its north pole is one of the most enduring mysteries of the solar system -- it was first observed by the Voyager probes in the early 1980's. Thought to be caused by high-altitude jet streams, the hexagon, as recently imaged by the Cassini mission, also seems to rotate with Saturn's inner core and global magnetic field. Although the underlying flow dynamics of this feature is not entirely understood.

MORE: Cassini Photographs Saturn's Stunning Hexagon

There are few worlds that hold more promise than Saturn's largest moon Titan. The moon is known to have a thick atmosphere, large bodies of liquid methane and ethane, hydrocarbon-rich landscapes filled with rivers and valleys, and vast dune fields. One would be mistaken in thinking this moon is in fact an embryonic Earth, filled with organic potential. It may be frozen and unsuitable for life as

we

know it, but astrobiologists dream of having a follow-up mission to Titan after seeing the European Huygens lander (which hitched a ride to Saturn on board Cassini) float down and land on the moon in 2005.

VIDEO: Is Titan Older Than Saturn?

To add to the familiarity of Titan with a young Earth, Cassini spotted waves in one of the large Titanian seas, whipped up by surface winds. Shown here at an oblique angle, the waves can be seen glinting in the sunlight.

MORE: Cassini Spies Wind-Rippled Sea on Titan

Zooming in on Titan's vast dune fields during multiple flybys, Cassini has shown us even more Earth-like aeolian (wind-blown) features. In the case of Titan's black dunes, small grains of organic compounds have been blown into rippled 'seas' of their own.

MORE: Cassini Spies Titan's Undulating Dunes

With Cassini's high-resolution cameras, the mission has captured countless dreamy shots of the planet's 62 moons. Shown here is one of Discovery News readers' favorites: Saturn's moon Mimas looming ominously with the smaller moon Pandora passing behind. Mimas is also nicknamed the "Death Star Moon" in reference to Star Wars, with the moon's large Herschel Crater resembling the Death Star's planet-killing superweapon.

MORE: Saturn's Pandora Flirts with 'Death Star' Moon

When it comes to organic chemistry, it's not all about Titan. The small icy moon of Enceladus isn't only famous for its impressive water-rich geysers that also have hints of life-giving chemistry, there's also the possibility that the moon has extensive sub-surface seas of liquid water. It is almost like a mini-Europa, Jupiter's second-largest moon, and scientists are keen to find out what lies beneath both moons' cracked crust.

MORE: Saturn's Moon Enceladus Has Underground Ocean

In a surprise discovery this year, Cassini made the chance observation of

something

in one of Saturn's rings. Could this bright knot in the outer edge of the gas giant's A ring be the birth of a baby moon? Astronomers think it might, providing new clues as to the formation of natural satellites and proving that although our solar system is old, its planets still have active moon-formation processes persisting to this day.

MORE: Saturn May Have Given Birth to a Baby Moon

Like Saturn's weird hexagon, the bright 'spokes' in Saturn's rings have puzzled astronomers for some time. Originally spotted by the Voyager flybys in the early 1980s, Cassini has been monitoring the phenomenon and revealed that they are not caused by gravitational interactions in or around Saturn. Instead, they are most likely generated by the interaction between dust in the planet's B ring and Saturn's global magnetic field that threads through the ring system.

MORE: Mysterious 'Spokes' in Saturn's Rings are Still There

In a breathtaking observation, the impact of one of Saturn's tiny moons on the planet's outermost ring was captured by Cassini. Prometheus, which is only 53 miles across, periodically careens through the F-ring, creating channels and streamers through the icy particles.

MORE: Tiny Moon Prometheus Rips-Up Saturn's Outer Ring

In one of the most iconic space photographs ever taken, in July, 2013, Cassini looked back at Earth from nearly 900 million miles away. Earth is just a dot of light and the moon is even smaller. This image reminds us, like Voyager's famous "Pale Blue Dot" photo did in the 1990s, how tiny we are when compared with the immensity of space and Cassini continues to inspire the people on our tiny planet that we are capable of doing great things.

MORE: The Pale Blue Dot: Here's Looking At Us, Earthlings