Countdown: NASA's First Attempt to Loft the New Horizons Probe

NASA's first attempt to launch its New Horizons spacecraft on a more than nine-year mission to Pluto ended in a scrub Tuesday less than three minutes before its planned liftoff.

High winds thwarted the attempted the attempted space shot, preventing New Horizons and its Lockheed Martin-built Atlas 5 booster from launching during a window that stretched between 1:24 p.m. EST and 3:23 p.m. EST (1824-2023 GMT).

Here's how the day's countdown unfolded beginning with the most recent update:

UPDATE: 3:25 p.m. EST

Scrub! Launch officials scrubbed today's launch of the Pluto-bound New Horizons spacecraft due to high winds at the probe's Cape Canaveral launch pad.

The scrub occurred just with just two minutes and 42 seconds remaining in the countdown, when weather officers detected winds blowing at 33 knots - the maximum limit for the New Horizons spacecraft and its Atlas 5 rocket.

Flight controllers are now preparing New Horizons and its Atlas 5 rocket for a 24-hour turnaround. The spacecraft is now set to launch on Jan. 18 at 1:16 p.m EST (1816 GMT). Like today, the spacecraft has a one-hour and 59 minute launch window tomorrow that closes at 3:15 p.m. EST (2015 GMT).

A wrap up of today's scrubbed launch attempt can be found by clicking here.

UPDATE: 3:19 p.m. EST

The count is T-4 minutes and counting for NASA's New Horizons mission to Pluto. The spacecraft is set to launch at 3:23 p.m. EST (2023 GMT).

After a series of delays, primarily due to high winds, launch officials are once again poised to loft the New Horizons spacecraft on a mission to the planet Pluto and beyond.

Flight controllers are hopeful that the wind speeds at New Horizons' Cape Canaveral Air Force Station launch pad will remain below the acceptable limit, but will scrub the space shot if they get too high.

UPDATE: 3:05 p.m. EST

NASA has again retargeted its launch time for the Pluto-bound New Horizons spacecraft to 3:23 p.m. EST (2023 GMT) - the end of today's flight window - in order to better understand strong ground winds at the probe's Cape Canaveral Air Force Station launch site.

Strong winds, both on the ground and at upper levels, have been a cause of concern for flight controllers throughout today's countdown. While launch officials are confident that the upper level windows are within the acceptable boundaries, they need more time to evaluate ground level winds, NASA officials said.

Wind speeds on the ground at New Horizon's Complex 41 launch pad have danced around the upper limit - 33 knots - set by launch guidelines. Tucked inside its Lockheed Martin-built Atlas 5 rocket, New Horizons was slated to launch at 1:24 p.m. EST (1824 GMT).

If the spacecraft misses today's launch window, the next window opens on Wednesday, Jan. 18. New Horizons has daily launch windows running through Feb. 14, but must launch by Feb. 2 in order to take advantage of a Jupite rflyby next year that could shave years of its Pluto-bound journey.

UPDATE: 2:45 p.m. EST

NASA has once more reset the launch of its New Horizons Pluto probe. The spacecraft is now set to launch at 3:05 p.m. EST (2005 GMT).

High ground and upper wind speeds have dogged today's launch countdown for the New Horizons probe and its Atlas 5 rocket. All other concerns, including a tracking station problem and a liquid oxygen vent glitch, have been resolved.

Flight controllers must launch New Horizons by 3:23 p.m. EST (2023 GMT), when today's window closes, or reset for tomorrow. There is a launch window for New Horizons each day through Feb. 14, though a liftoff by Feb. 2 will shave three years off the spacecraft's trip to Pluto.

UPDATE: 2:27 p.m. EST

A new launch time has been set for 2:50 p.m. EST (1950 GMT) for NASA's New Horizons Pluto probe due to a problem with the agency's Deep Space Network (DSN), NASA officials said.

The DSN array of radio antennas situated around the globe was not initially expected to be ready for a 2:30 p.m. EST (1930 GMT), though apparently is now back online. The delayed launch time will allow extra checks to ensure the network, which tracks spacecraft on deep space missions, is ready for today's liftoff.

NASA's New Horizons spacecraft is slated to explore Pluto and its moons during a July 2015 flyby, meeting the planet at a distance of about three billion miles from Earth.

Today's launch window extends until 3:23 p.m. EST (2023 GMT).

UPDATE: 2:10 p.m. EST

A tracking station required to launch NASA's New Horizons on its mission to Pluto has gone offline, NASA officials said.

The station, based in Antigua, is required to monitor the launch of New Horizons atop its Atlas 5 booster, but suffered a glitch with its command transmitter, NASA spokesperson Bruce Buckingham said.

Launch controllers are confident the station will be back online by 2:20 p.m. EST (1920 GMT), about 10 minutes before today's planned liftoff. High wind speeds continue to be a concern.

NASA's New Horizons spacecraft is the first probe ever built to visit Pluto, its moons and the Kuiper Belt objects beyond the planet's orbit. The spacecraft's launch window closes at 3:23 p.m. EST (2023 GMT) today, though additional opportunities will occur daily through Feb. 14.

UPDATE: 2:00 p.m. EST

Wind speeds both on the ground at at high altitudes continue to cause concern for flight controllers overseeing today's launch of NASA's New Horizons spacecraft destined for Pluto.

Flight controllers are now aiming at a 2:30 p.m. EST (1930 GMT) launch time. Earlier, high altitude winds were reportedly stronger than launch criteria allow, though weather officers are awaiting data from their latest round of balloon monitors. Ground level winds were gusting very close to the upper limit, 33 knots, allowable for an Atlas 5 launch.

Today's launch window will close at 3:23 p.m. EST (2023 GMT).

UPDATE: 1:45 p.m. EST

NASA now hopes to launch its New Horizons spacecraft at 2:10 p.m. EST (1910 GMT) today, pushing the space shot back a second time in less than one hour due to concerns of high winds.

Originally set to launch at 1:24 p.m. EST (1824 p.m. EST) today, the Pluto-bound New Horizons probe and its Atlas 5 booster was pushed back to 1:45 p.m. EST (1845 GMT) to allow additional time to study wind conditions and vent valve glitch on the rocket's first stage.

Flight controllers have been tracking wind speeds throughout today's launch countdown. Winds have been blowing steadily at 25 knots, with gusts reaching - and sometimes surpassing - the launch's 33-knot limit.

Today's launch window closes at 3:23 p.m. EST (2023 GMT).

UPDATE: 1:20 p.m. EST

Flight controllers have pushed the launch of NASA's Pluto-bound New Horizons spacecraft back just over 15 minutes to allow additional time to work a pair of ongoing issues.

New Horizons is now set to launch at 1:45 p.m. EST (1845 GMT) today. The extra time will allow engineers more time to study a finicky liquid oxygen fill and drain vent valve, which appears to working as expected. The added time will also allow weather officers a chance to track wind speeds at New Horizons' launch site.

Launch controllers have been concerned that gusts of wind could exceed their launch parameters for today's planned space shot.

New Horizons was originally set to launch at 1:24 p.m. EST (1824 GMT) today - the opening of its nearly two-hour launch window. That window closes at 3:23 p.m. EST (2023 GMT). The Pluto probe has a launch window each day through Feb. 14, though mission scientists hope to loft the spacecraft by Feb. 2 in order to swing past Jupiter next year and snag a gravity boost towards Pluto.

UPDATE: 1:10 p.m. EST

The countdown for NASA's Pluto-bound New Horizons spacecraft has paused at T-4 minutes for a scheduled 10-minute hold before proceeding with today's planned launch.

New Horizons is set to launch atop its Atlas 5 booster at 1:24 p.m. EST (1824 GMT), though engineers are studying a valve issue with the spacecraft's booster. Flight controllers are also watching high wind speeds at the probe's Launch Complex 41 launch pad at Cape Canaveral Air Force Station.

UPDATE: 1:00 p.m. EST

Engineers are working a valve glitch with the Atlas 5 booster set to launch NASA's Pluto-bound New Horizons spacecraft later today, one of two issues launch controllers are watching in preparation for the planned space shot.

Mission managers are studying a whether a fill and drain valve for one of the rocket's liquid oxygen tanks will close as required for today's launch. Readings from a test of the liquid oxygen vent valve were not as expected, mission controllers reported.

Meanwhile, weather officers continue to monitor winds at New Horizons' launch site at Cape Canaveral Air Force Station. Winds are blowing at a steady 25 knots with gusts reaching 33 knots, the upper limit according to Atlas 5 flight rules, NASA officials said.

With just minutes remaining in the launch countdown for New Horizons, flight controllers continue to work toward a 1:24 p.m. EST (1824 GMT) liftoff.

UPDATE: 12:50 p.m. EST

Less than 30 minutes remain in the countdown to launch NASA's Pluto-bound New Horizons spacecraft. A built-in hold in the countdown will occur at T-four minutes.

New Horizons is on track to launch from Cape Canaveral Air Force Station's Complex 41 at 1:24 p.m. EST (1824 GMT). Aside from high wind gusts, which weather officials continue to track, the outlood looks good for today's space shot, NASA officials said.

UPDATE: 12:30 p.m. EST

Pad workers have nearly completed loading liquid hydrogen propellant aboard the upper stage of NASA's New Horizons spacecraft's Atlas 5 rocket.

Launch controllers are watching local wind speeds closely as they continue to prepare New Horizons' Atlas 5 rocket for flight.

UPDATE: 12:15 p.m. EST

Engineers continue the loading of liquid oxygen aboard the Atlas 5 booster for NASA's New Horizons spacecraft set to launch toward Pluto today.

High wind speeds continue to be a concern for today's launch. NASA spokesperson Bruce Buckingham said winds are blowing steadily at about 25 knots at New Horizons's Cape Canavaral Air Force Station launch site. But gusts have reached 35 knots, just over the 33 knot limit for today's planned space shot, he added.

An update on weather conditions at and above New Horizons' Complex 41 launch pad is expected shortly.

New Horizons is set to launch at 1:24 p.m. EST (1823 GMT) today, but does have some room for delay if needed. Today's launch window closes at 3:23 p.m. EST (2023 GMT).

UPDATE: 11:57 a.m. EST

New Horizons principal investigator Alan Stern said the timing of today's launch is particularly apt.

The spaceflight is a fitting tribute for astronomer Clyde Tombaugh, who discovered Pluto in 1930 and died nine years ago today, almost to the hour of New Horizons' planned liftoff, Stern said.

Tombaugh's wife Patsy and two grown children have traveled to Cape Canaveral to watch today's planned launch.

Meanwhile, pad engineers have just about filled the Centaur upper stage of New Horizons' Atlas 5 rocket with liquid oxygen and will have to top the booster off periodically as it boils away. The rocket's first stage is about 10 percent full with the supercold liquid.

UPDATE: 11:55 a.m. EST

As the clock ticks down toward the launch of NASA's Pluto-bound New Horizons spacecraft, engineers have begun loading liquid oxygen propellant into the probe's Atlas 5 booster. The rocket's Centaur upper stage is almost filled with the cryogenic liquid.

Once both Atlas 5 rocket's first stage and its Centaur upper stage are filled with liquid oxygen, engineers will begin loading liquid hydrogen into their respective tanks, NASA officials said.

UPDATE: 11:35 a.m. EST

Today's countdown for the launch of NASA's Pluto-bound New Horizons spacecraft continues to go smoothly.

Launch pad workers have begun loading supercold liquid oxygen aboard New Horizons' Atlas 5 booster's upper stage is and about 13 percent complete, NASA officials said. The Lockheed Martin-built rocket carries five strap-boosters that will generate almost three million pounds of thrust at launch, slinging New Horizons on what NASA officials have said is their fastest mission to date.

A Centaur upper stage is designed to kick in once New Horizons reaches space and perform two burns to send New Horizons on its way. Once liquid oxygen loading of the Centaur is complete, pad workers will load the chilled liquid into the rocket's Atlas stage, then proceed to load liquid hydrogen aboard the rocket.

UPDATE: 11:15 a.m. EST

Omar Baez, NASA's launch manager, said today's launch of the New Horizons Pluto probe is proceeding smoothly with no technical issues so far. The countdown has picked up at T-2 hours.

Baez said flight controllers are watching the wind speeds at New Horizons' launch site at Complex 41 at Cape Canaveral Air Force Station in Florida. Wind speeds were reported at about 29 knots, still below the limit of 33 knots, Baez said.

NASA's Kennedy Space Center director Jim Kennedy said New Horizons is carrying Florida quarter coin to honor its launch site.

UPDATE: 11:00 a.m. EST

NASA's first spacecraft to the planet Pluto is poised to launch spaceward atop its Atlas 5 booster.

The New Horizons spacecraft is set to lift off from its launch pad at Cape Canaveral Air Force Station in Cape Canaveral, Florida at 1:24 p.m. EST (1824 GMT), though today's flight window will stretch until about 3:23 p.m. EST (2023 GMT). New Horizons is slated to spend about nine years flying toward Pluto, during which it is expected to swing past Jupiter next year. If all goes well, the spacecraft is designed to reach Pluto as early as July 2015.

"It's a great day," NASA chief Michael Griffin said today at the agency's Kennedy Space Center (KSC) near the launch site. "This is a milestone event for NASA."

About the size of a piano, New Horizons carries seven primary science instruments powered by a radioisotope thermal generator (RTG), which converts heat from decaying pieces of plutonium into energy for spacecraft systems.