India launches its first mission to Mars on Tuesday, aiming to become the only Asian nation to reach the Red Planet with a programme designed to showcase its low-cost space technology.
A rocket carrying a 1.35-tonne unmanned probe will blast off at 02:38pm (0908 GMT) from the Sriharikota spaceport off the southeast coast, beginning a 300-day journey to study the Martian atmosphere.
"The countdown is progressing normally. All the tests are going on well," said Deviprasad Karnik, spokesman for the Indian Space Research Organisation (ISRO), shortly before blastoff. "The weather is normal. Slightly cloudy but no problem."
The Mars Orbiter Mission, known as "Mangalyaan" in India, was announced 15 months ago by Prime Minister Manmohan Singh, shortly after a Chinese probe flopped when it failed to leave Earth's atmosphere.
The timing led to speculation that India was seeking to make a point to its militarily and economically superior neighbour, despite denials from ISRO.
"We are in competition with ourselves in the areas that we have charted for ourselves," ISRO chairman K. Radhakrishnan told AFP last week.
The gold-coloured probe, the size of a small car, has been hurriedly assembled and will be carried by a rocket much smaller than US or Russian equivalents.
Lacking the power to fly directly, the 350-tonne launch vehicle will orbit Earth for nearly a month, building up the necessary velocity to break free from our planet's gravitational pull.
Only then will it begin the second stage of its nine-month journey which will test India's scientists to the full, five years after they sent a probe called Chandrayaan to the moon.
An hour and half before takeoff, the red and black rocket had been fully filled with propellent and stood alone on the launchpad after the mobile servicing tower was withdrawn.
More than half of all Mars projects have failed, including China's in 2011 and Japan's in 2003. Only the United States, Russia and the European Union have successfully reached there.
The cost of the project is 4.5 billion rupees ($73 million), less than a sixth of the 455 million dollars earmarked for a Mars probe to be launched by NASA this month.
"We didn't believe they'd be able to launch this early," project scientist for the NASA Mars probe, Joe Grebowsky, told AFP. "If it's successful, it's fantastic."
He underlined that Mars, which has a complicated orbit meaning it is between 50-400 million kilometres from Earth, was a far more complex prospect compared with a moon mission.
"When you shoot a rocket at Mars you have to take into account that Mars is going to move a good deal before you get there. The moon is fairly close," he said.
There have been recent setbacks for India too, including when Chandrayaan lost contact with its controllers in 2009. Another launch vehicle blew up after take-off in 2010.
India has never before attempted an inter-planetary journey, meaning new technology had to be developed to enable the probe to run autonomously. Communication signals take 12 minutes to travel between Earth and Mars.
The programme also has to contend with critics who say a country that struggles to feed its people adequately and where more than half have no toilets should not be splurging on space travel.
ISRO counters that its technology has helped economic development through satellites which monitor weather and water resources, or enable communication in remote areas.
The Bangalore-based organisation and its 16,000 staff also share their rocket technology with the state-run defence body responsible for India's missile programme.
The United States is the only nation that has successfully sent robotic explorers to land on Mars, the most recent being Curiosity which touched down in August 2012.
One of its discoveries appeared to undercut the purpose of the Indian mission which is to find evidence of methane which would lend credence to the idea of Mars supporting a primitive form of life.
A study of data from Curiosity published in September found the rover had detected only trace elements of methane in the atmosphere.
"Remember that it (Curiosity's methane reading) is for a single spot. One point doesn't make it a story for the whole planet," top Indian space scientist Jitendra Nath Goswami told AFP.
NASA, which will launch its Maven probe on November 18 to study why Mars lost its atmosphere, is helping ISRO with communications.
Clouds of methane have previously been identified by telescopes on Mars, but the gas has never been confirmed by a mission there.
Methane on Earth is mostly produced by micro-organisms, so a positive reading would suggest some form of life on a planet that scientists believe was once covered with water.