Spaceflight101’s MAVEN updates page
Eighteen successful missions to Mars have established that the planet has an atmosphere that’s too thin to support all the water that once flowed there. Long ago, air must have been thicker there – as it is today on Earth.
To find answers to those questions, the MAVEN spacecraft (it makes a cameo in the video) was sent to Mars and will reach it on September 21st.
After orbital insertion and a commissioning phase, it will then start a one-year study of space near the Red Planet as well as of the upper layers of the present-day Martian atmosphere.
The present is the key to the past
Okay. Water and other volatiles could have gone into the Red Planet’s crust, or maybe they floated off into space. But how can anybody study an atmosphere that isn’t there any more?
Armed with both this data and the reliable principle first proposed by Charles Lyell that the present is the key to the past, they will then extrapolate back to see how much atmosphere Mars has lost and how its stable isotopes have behaved over its 4-billion-year history.
Isotopes are very helpful in tracking geologic and atmospheric processes. Scientists say, “Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation.”
The Curiosity rover has been measuring these ratios at the surface of Mars. MAVEN will measure them in the planet’s upper atmosphere.
Right now, the key working hypothesis is (PDF), “Turn-off of the Martian magnetic field allowed turn-on of solar-EUV and solar-wind stripping of the atmosphere approximately 4.0 billion years ago, resulting in the present thin, cold atmosphere.”
MAVEN at Mars
The spacecraft is as long as a school bus and weighs as much as a fully loaded SUV. At present, it’s bopping along at a little over 60,000 mph (96,720 kph). On September 21st, it’s going to slow down (PDF), burning more than half of its fuel in 33 minutes as a brake, and enter Mars orbit at a point about 240 miles (380 km) over the north pole.
While it is preparing to start its mission, MAVEN will have to be moved to the other side of Mars for about 20 minutes as Comet Siding Spring swishes through, some 82,000 miles (132,000 km) away.
The comet’s nucleus won’t hit Mars, and the Red Planet probably won’t even get a dust shower, but mission planners want to be safe during the short span of highest risk of particle impacts.
The nice thing is that an orbiter designed to study atmosphere has just gotten into an ideal observation as a comet (which, this close to the Sun, is mostly atmosphere) passes by. Yes, they’re excited at NASA.
“We hope to witness two atmospheres colliding,” David Brain of the University of Colorado’s Laboratory for Atmospheric and Space Physics (LASP) says in a press release. “This is a once in a lifetime event! … “It is possible that the atmosphere of the comet will interact with the atmosphere of Mars. This could lead to some remarkable effects — including Martian auroras.”
When all the excitement has died down and MAVEN has completed its commissioning phase, about six weeks after arriving at Mars, it will commence its science work.
NASA says that the elliptical orbit (which is also going to change its rotational axis in both latitude and solar time to get the best samples), also lets MAVEN pass through all relevant levels of the upper Martian atmosphere. In addition, over the year-long study, the mission team will send the spacecraft down on five “dips” closer than 100 miles to the surface.
It’s going to be a lot of work, but the orbital pattern will be quite an achievement if they can bring it off without a hitch.
Yes, there is always uncertainty involved in space travel. Mars is notorious for the number of missions there that have failed. One of MAVEN’s predecessors, the Mars Climate Orbiter, was lost on arrival simply because one team had used English units of measure and another had used metric units.
“The lessons from these reviews will be applied across the board in the future,” Dr. Edward Weiler of NASA said about it.
The next mission, a year later, a polar lander, crashed, possibly because a software error shut down its engines too early during descent.
However, all missions after that – other than the Beagle lander and a joint Soviet/Chinese mission that failed to leave Earth orbit – have been successful to date.
All the best to MAVEN – the biggest Mars orbiter and one that can give us an unprecedented look into Martian atmosphere and climate change!
In the meantime another orbiter, the Mars Express, has already proven that a planet with no surface water can be surprisingly beautiful.
- Mars Probes from US and India Arrive at Red Planet This Month. Elizabeth Howell
- Mars Evolution and Volatile Evolution (MAVEN). NASA mission page
- Mars Evolution and Volatile Evolution (MAVEN). NASA science page
- MAVEN mission presentation (PDF). NASA
- MAVEN: 7 Things to Know About NASA’s Mars Orbiter. Ian O’Neill
- MAVEN. Wikipedia