How does the Mars Phoenix Lander analyse samples?
One of the instruments aboard the Mars Lander has been described as sniffing chemicals after heating samples of soil up. How are the effects of the Martian atmosphere taken into account. Is the container set to a vacuum or is the background reading from the atmosphere subtracted out?
We spoke to William Boynton on the show back in May about the mission so we decided to get back in touch with him to answer this question...
"We put the sample into a very small oven about the size of two drops of water and seal it to isolate it from the atmosphere. We then flush out the atmosphere that was sealed in the oven with the sample with a flow of pure nitrogen gas. The nitrogen gas is called a carrier gas and besides removing the atmosphere it is used to carry the evolved vapours generated during the heating over to the evolved gas analyser known as the sniffer. This sniffer is a mass spectrometer - a machine that you can find in any chemistry lab back here on Earth. This can accurately tell what molecules and atoms are in the sample."