NASA's New Horizons spacecraft has beamed latest images of Pluto, as the probe makes way towards a historic encounter with the icy dwarf planet.
Although still just a dot along with its largest moon, Charon, the images come on the 109th birthday of Clyde Tombaugh, who discovered the distant icy world in 1930.
New Horizons was nearly 203 million kilometres away from Pluto when it began taking images.
— NASA (@NASA) February 4, 2015
The new images, taken with New Horizons' telescopic Long-Range Reconnaissance Imager (LORRI) on January 25 and January 27, are the first acquired during the spacecraft's 2015 approach to the Pluto system, which culminates with a close flyby of Pluto and its moons on July 14.
"These images of Pluto, clearly brighter and closer than those New Horizons took last July from twice as far away, represent our first steps at turning the pinpoint of light Clyde saw in the telescopes at Lowell Observatory 85 years ago, into a planet before the eyes of the world this summer," said Alan Stern, New Horizons principal investigator at the Southwest Research Institute (SwRI) in Boulder, Colorado.
Over the next few months, LORRI will take hundreds of pictures of Pluto, against a starry backdrop, to refine the team's estimates of New Horizons' distance to Pluto.
The Pluto system will resemble little more than bright dots in the camera's view until late spring.
However, mission navigators can still use such images to design course-correcting engine manoeuvres to direct the spacecraft for a more precise approach.
The first such manoeuvre based on these optical navigation images, or OpNavs, is scheduled for March 10.
"Pluto is finally becoming more than just a pinpoint of light," said Hal Weaver, New Horizons project scientist at the Johns Hopkins University Applied Physics Laboratory.
"LORRI has now resolved Pluto, and the dwarf planet will continue to grow larger and larger in the images as New Horizons spacecraft hurtles towards its targets. The new LORRI images also demonstrate that the camera's performance is unchanged since it was launched more than nine years ago," said Weaver.
Closing in on Pluto at about 49,890 kph, New Horizons already has covered more than 3 billion miles since it launched on January 19, 2006.
Its journey has taken it past each planet's orbit, from Mars to Neptune, in record time, and it is now in the first stage of an encounter with Pluto that includes long-distance imaging as well as dust, energetic particle and solar wind measurements to characterise the space environment near Pluto.