Mars atmospheric probe blasts off aboard Atlas 5
BY STEPHEN CLARK
Posted: November 18, 2013
A United Launch Alliance Atlas 5 rocket dispatched a $671 million gas-sniffing sleuth to Mars on Monday, taking the first step in a long-distance voyage across the solar system to survey the Martian atmosphere and decipher an enigma nearly as old as the solar system itself.
The Mars-bound spacecraft, weighing as much as a fully loaded SUV, blasted off at 1:28 p.m. EST (1828 GMT) from Cape Canaveral, Fla.
Dodging clouds from an incoming weather front, the 188-foot-tall Atlas 5 launcher leisurely ascended from Cape Canaveral's Complex 41 on the power of its Russian-made RD-180 engine.
Getting lighter as the first stage burned its supplies of propellant, the Atlas 5 broke the sound barrier about a minute-and-a-half later, rocketing into the stratosphere and leaving Earth's veneer of air behind.
The rocket's kerosene-fueled first stage, painted a gleaming bronze, shut down and jettisoned about four minutes after liftoff, yielding to a Centaur upper stage for the final maneuvers to place the 5,420-pound MAVEN spacecraft on a hyperbolic escape trajectory to break free of the grip of Earth's gravity.
The Centaur stage released the MAVEN probe about 53 minutes into the mission, notching another success for ULA's workhorse Atlas 5 rocket, which made its seventh flight of the year Monday.
A few minutes after separation from the Atlas 5 rocket, MAVEN radioed its status to antennas in Australia, confirming its health as it extended two appendages containing more than 2,000 power-generating solar cells to begin charging the craft's batteries.
By 4 p.m. EST, two-and-a-half hours after launch, MAVEN was 14,000 miles from Earth and speeding away.
The Mars Atmosphere and Volatile Evolution mission, or MAVEN, was conceived to solve the mystery of how the Martian atmosphere was stripped from the red planet, a landmark event that eroded the world's ability to support life.
Bruce Jakosky, a scientist at the University of Colorado at Boulder, dreamed up the mission 10 years ago.
"After 10 years of doing this, I don't have the words to describe what I'm feeling," Jakosky said. "It's every possible emotion, but they're all positive."
After winning funding from NASA in 2008, MAVEN was given a launch opportunity in November 2013.
"Five years ago, we put in Nov. 18, 2013, as our planned launch date, and we hit it," Mitchell said.
Big challenges loom ahead of MAVEN, especially a crucial 38-minute thruster firing in September 2014 to put the school bus-sized spacecraft in orbit around Mars.
Before then, MAVEN will go through a program of testing and checkouts to ensure everything is in tip-top shape for the Mars arrival on Sept. 22, 2014.
"I've been incredibly nervous for the last 10 years," Jakosky said. "I know that we do lose spacecraft on launch. Not every launch goes smoothly. In fact, that's the single biggest potential opportunity to lose the mission, so getting past this hurdle is a really big one. Now we get to the next hurdle where have potential to lose the mission, which will be Mars orbit insertion."
MAVEN's next milestone is a Dec. 3 engine burn to adjust the probe's path toward Mars, the first of four course correction maneuvers planned during the mission's 10-month cruise. The Dec. 3 burn will adjust MAVEN's course to aim for Mars. Engineers purposefully put the spacecraft on a trajectory to miss the red planet following launch because the Atlas 5 rocket's Centaur stage is shadowing MAVEN on the escape path from Earth.
Mitchell said ground controllers will start activating MAVEN's eight science instruments for tests in December, and some of the payloads will take data during the voyage to Mars. MAVEN's ultraviolet imaging spectrometer will observe comet ISON in December, Jakosky said.
Once MAVEN is at Mars, the probe will drop into an operational elliptical orbit. MAVEN is due to begin collecting science by early November 2014, according to NASA.
MAVEN will do a lap around Mars ever four-and-a-half hours, reaching as far as 3,860 miles from the planet and as close as 93 miles above its surface, close enough for the spacecraft sample the upper atmosphere each time around.
Five times during its one-year prime mission, MAVEN will alter its orbit to dip deeper into the wispy layers of gas enshrouding Mars, plowing through the atmosphere just 77 miles above the red planet.
"If you put your hand while you're going through, you would feel a light breeze," said Guy Beutelschies, MAVEN program manager at Lockheed Martin Corp. "It's really a modest amount of pressure out there, but it is a tremendous value for the scientists to be able to go down and get that in situ measurement of the atmosphere."
MAVEN's solar panels are canted at an angle on each end, making the spacecraft more aerodynamic when it flies through the outer atmosphere of Mars, according Beutelschies.
The spacecraft is outfitted with instrumentation to keep track of solar activity, measure the make-up of the Martian upper atmosphere, and observe how the atmosphere moves, grows and shrinks during the mission.
NASA has committed to paying for MAVEN to collect scientific data for at least one year - until late 2015 - but the platform has enough fuel to last up to a decade.
One of MAVEN's ancillary objectives is to serve as a communications relay platform for NASA's rovers on the surface of Mars. The space agency relies on orbiters above Mars to function as faster radio links with the rovers than if engineers were forced to communicate with them directly.
But research is the reason for MAVEN's existence.
"It's clear that major questions about the history of Mars center on the history of its climate and atmosphere, and how that's influenced the surface, geology and the possibility for life," Jakosky said.
Scientists know Mars today is a barren world with its water locked up underground or in immense polar ice caps. Thanks to missions like the Curiosity and Opportunity rovers, geologists have obtained a window into the Martian environment billions of years ago, when Mars had ample flowing water and all the chemical ingredients required to give rise to life.
But there is something missing.
Data from previous missions lack insight into how and when Mars changed, and MAVEN's job is to find out what triggered the dramatic climate shift.
"We're trying to understand basically why the climate chnaged on Mars, why Mars appears to have gone from an environment that was habitable - to microorganisms at least - to one that is the cold, dry, uninhabitable environment we see today," Jakosky said.
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