DHAKA: New Horizon's photos replace the only tiny pixelated images of Pluto we have had prior to now, and reveal specifics of Pluto previously only subject to speculation.

On schedule, at 8:52:37 p.m. Eastern time, a message from the spacecraft arrived at Mission Control here at the Johns Hopkins Applied Physics Laboratory.

"This is truly a hallmark in human history," said NASA's head of the science mission directorate, John Grunsfeld, reports wired.com

Alan Stern, the mission's principal investigator, said it was "a moment of celebration because we have done the anchor leg".

"We have completed the initial reconnaissance of the solar system, an endeavour started under president [John F] Kennedy more than 50 years ago, continuing today under president Barack Obama."

Stern also said it was very fitting that Tuesday marked the completion of New Horizons' exploration of Pluto, as it was exactly 50 years ago on that day that the first spacecraft flew to Mars.

Missions operation manager Alice Bowman said she had to "pinch herself" when she thinks about what they have accomplished.

"It's truly amazing that humankind can go out and explore these worlds," she said.

New Horizons' most recent reports show the dwarf planet to be 2,370 kilometres across, which is slightly larger than was estimated when the planet was downgraded from planet status to a dwarf planet.

Scientists also confirmed the existence of a polar ice cap on Pluto, and found nitrogen escaping from its atmosphere.

New Horizons is the fastest spacecraft ever launched and is carrying an ounce of ashes of American astronomer Clyde Tombaugh, who discovered Pluto.

The mission launched in 2006, the same year that Pluto was downgraded to "dwarf planet" status due to the celestial body's small size and New Horizons is the first spacecraft to fly past Pluto.

BDST: HRS, JULY 10, 2015