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Updated: Aug 12, 2018 13:54 IST

NASA on Sunday launched its ambitious Parker Solar Probe a day later than it was scheduled to after multiple checks exhausted the launch window.

Liftoff took place from Space Launch Complex 37 at Cape Canaveral Air Force Station in Tampa, Florida.

The Parker probe is expected to come within 6.16 million kms (3.83 mn miles) of the sun, the closest a spacecraft has ever gotten to the star.

The mission will last 6 years and 11 months, and in that time the Parker probe will orbit the sun 24 times. With each orbit it will push closer and closer to the sun, ultimately circling the star at a distance that is less than 10 radii of the sun.

No wonder scientists consider it the coolest, hottest mission under the sun, and what better day to launch to the sun than Sunday as NASA noted.

3-2-1… and we have liftoff of Parker #SolarProbe atop @ULAlaunch’s #DeltaIV Heavy rocket. Tune in as we broadcast our mission to "touch" the Sun: https://t.co/T3F4bqeATB pic.twitter.com/Ah4023Vfvn — NASA (@NASA) August 12, 2018

The launch was called off at the last minute on Saturday after a gaseous helium pressure red alarm emerged that the scientists did not have enough time to troubleshoot.

“The launch of a United Launch Alliance Delta IV Heavy rocket carrying the Parker Solar Probe spacecraft was scrubbed today due to a violation of a launch limit, resulting in a hold,” Nasa, said in a statement. “There was not enough time remaining in the window to recycle.”

The mission, that costs about $ 1.5 bn has been over five decades in the making, and is unique for bringing a space probe closer to the sun than any man made object.

One of the reasons, scientists are sending the probe is the Sun’s atmosphere and the weird property it exhibits, of being hotter than the surface of the sun itself. It is a puzzle because the further one moves from the source of heat the temperatures should fall.

The other great mystery is the behaviour of ‘solar wind,’ a stream of charged particles emitted by the sun to release energy. A key question that the probe seeks to answer is how solar wind is accelerated, and for the first time it will be able to look for answers at the source of solar wind itself.

(With agency inputs)