India Mars mission: How much fuel do you need to get to Mars?
India launched its first spacecraft to Mars Tuesday at a price tag of $72 million. It takes less fuel to propel India's Mars orbiter 485 million miles to the Red Planet than you think.
Talk about range anxiety.
India launched its first spacecraft to Mars Tuesday on a trip that will last over 300 days at a cost of $72 million. The 3,000-pound orbiter named Mangalyaan – or "Mars orbiter" in Hindi – faces the unenviable task of traveling 485 million miles through space to visit the dusty, lonesome Red Planet.
It will take a lot of fuel, but perhaps not as much as you might think. In nearly half a century of flights to Mars, engineers have developed techniques for cutting down on fuel and harnessing the natural celestial movements of Earth and its neighbors to propel crafts through space.
To say it's a complicated journey is an understatement. You can't just aim a rocket at Mars and fire away. The Red Planet is a moving target, and so is the pad from which you launch. Instead, scientists must aim for where Mars will be once the orbiter has finished its journey.
In rocket science, it's called a Hohmann Transfer Orbit, or Minimum Energy Transfer Orbit, a theory first outlined in 1925 by a German scientist and used today by engineers to cut down on interplanetary fuel costs.
Picture the orbits of Earth and Mars as concentric circles with the Sun at the center. As Earth travels around the Sun, a vessel is launched not perpendicularly outward, but almost tangentially to Earth's path. The launch is timed so that the vessel enters Mars' orbit just as the Red Planet comes around.
"Instead of pointing your rocket directly at Mars, you boost the orbit of your spacecraft so that it’s following a larger orbit around the Sun than the Earth," explains Fraser Cain, publisher of Universe Today, a space news site. "Eventually that orbit will intersect the orbit of Mars – at the exact moment that Mars is there too."
Even with the most efficient flight plan, getting to Mars is still an astronomically energy-intensive venture. The hardest part, of course, is blasting your way out of Earth's gravitational pull – its "Sphere of Influence" (SOI).
In India's Mars mission, it took a launch vehicle called PSLV-C25, measuring 145 feet long and carrying over 200 tons of propellant fuel. That's less than half the fuel a space shuttle mission routinely carried. In terms of weight, it's slightly less than 1 percent of the fuel the US Air Force uses in a day.
Six main engine burns move the craft out of Earth's SOI and into a hyperbolic trajectory to arrive in Mars's SOI. From there, the Mars orbiter relies on one liquid engine and eight thrusters to position the craft in Mars's orbit and make adjustments along its exploration of the Red Planet.
But not everything on Mangalyaan is powered with jet propellant. Three solar panels, capable of generating about 840 watts during sunlit and normal incidence in Martian orbit, power the equipment onboard the craft used to investigate the planet's atmosphere.
Some question the amount of money and energy used for India's Mars mission, given 306.2 million Indians live without electricity, according to The World Bank. Others defend the mission, saying it's a worthwhile endeavor that helps establish the nation's standing in the world.
"These missions are important. These are things that give Indians happiness and bragging rights," Raghu Kalra of the Amateur Astronomers Association Delhi told USA Today. "Even a poor person, when he learns that my country is sending a mission to another planet, he will feel a sense of pride for his country, and he will want to make it a better place."