Comparing the present and early D/H ratios will allow the team to calculate how much hydrogen (and, therefore, water) has been lost over Mars' lifetime. MAVEN will also determine how much Martian atmosphere has been lost over time by measuring the isotope ratios of other elements in the very high atmosphere, such as nitrogen, oxygen, carbon, and noble gases like argon.
MAVEN is expected to reach Mars in 2014. By then, SAM on board the Curiosity rover will have made similar measurements from Gale crater, which will help guide the interpretation of MAVEN's upper atmosphere measurements.
Measuring isotopes in the atmosphere will reveal its present state. To find out what the Martian atmosphere was like in the past, scientists will use what they discover with MAVEN about the various ways the atmosphere is being removed. With that data, they will build computer simulations, or models, to estimate the condition of the Red Planet's atmosphere billions of years ago.
Scientists estimate Gale crater may have formed more than three billion years ago. Curiosity will grind up Gale crater minerals and deliver them to SAM so the isotope ratios can be measured, giving a glimpse at the Martian atmosphere from long ago, perhaps when it could have supported life. "SAM's inputs from the surface of past Martian history will help the MAVEN team work backwards to discover how the Martian atmosphere evolved," said Joseph Grebowsky of NASA Goddard, MAVEN Project Scientist.
"For example, MAVEN will focus primarily on how solar activity erodes the Martian atmosphere," adds Mahaffy. Things like the solar wind, a tenuous stream of electrically conducting gas blown from the surface of the Sun, and explosions in the Sun's a
|Contact: Nancy Neal-Jones|
NASA/Goddard Space Flight Center