Indian spacecraft Orbiter halfway to Mars

India's maiden mission to Mars is on course, with its spacecraft Orbiter crossing the halfway mark on its voyage to the red planet, four months after it left Earth Dec 1.

"The spacecraft Wednesday at 9.50 a.m. crossed the halfway mark of its journey to Mars along the designated helio (sun)-centric trajectory in the solar orbit," the state-run Indian Space Research Organisation (ISRO) said in a statement here.

As the fourth planet from the sun, Mars is the second smallest celestial body in the solar system, at a distance of 400 million km (250 million miles) from Earth. Named after the Roman god of war, it is also known as the red planet due to the presence of iron oxide in abundance, giving it a reddish appearance.

"In terms of radio distance, the 1,337 kg Orbiter is cruising at 39 million km away from earth, travelling at 1.55 km per second in the sun's orbit," the space agency said.

As a signal from Earth to the spacecraft and back takes four minutes and 15 seconds, the high gain antennal onboard the spacecraft will be activated for handling communications with the ground stations.

The Rs.450-crore Mars Orbiter Mission was launched Nov 5 from Sriharikota spaceport off the Bay of Bengal, about 80 km north east of Chennai, onboard a 350-tonne rocket with five scientific instruments to detect methane in the Martian atmosphere, measure the thermal emission and capture images of the red planet from its orbit at a distance of 500 km.

The spacecraft's journey through space is being monitored from India's deep space network at Bylalu (about 30km from Bangalore) and the Jet Propulsion Laboratory of the National Aeronautics and Space Administration (NASA) of the US.

"As the Orbiter is on its designated trajectory, the trajectory correction manoeuvre, which was planned to be undertaken this month, is not considered essential," the statement noted.

Space scientists and engineers are also conducting periodic tests at different levels of autonomy, built into the spacecraft for contingencies.

"The spacecraft and its five scientific instruments are in good health," the statement added.

Though earth and Mars have an equal period of revolution around their axis, the red planet takes 24 hours and 37 minutes to complete a revolution. Earth takes around 365 days to orbit the sun and Mars 687 days.

Once the Orbiter is placed in the Martian orbit in mid-September, about 500 km from its red surface, its five indigenous instruments onboard will commence their scientific observations.