Meteorites reveal story of Martian climate | Lawrence Livermore National Laboratory
https://www.llnl.gov/news/meteorites-reveal-story-martian-climate
Liquid water is not stable on Mars’ surface because the planet’s atmosphere is too thin and temperatures are too cold. However,
at one time Mars hosted a warm and wet surface environment that may have been conducive to life. A significant unanswered question
in planetary science is when Mars underwent this dramatic change in climate conditions.
New research by Lawrence Livermore National Laboratory (LLNL) cosmochemist Bill Cassata shows that, by looking at trapped gasses
in ancient Martian meteorites, the timing and effectiveness of atmospheric escape processes that have shaped Mars’ climate can be
pinned down. The research appears in Earth and Planetary Science Letters.
Cassata analyzed the Martian atmospheric gas xenon (Xe, in two ancient Martian meteorites, ALH 84001 and NWA 7034. The data indicate
that early in Martian history there was a sufficient concentration of atmospheric hydrogen to mass fractionated Xe (selectively removed
light isotopes) through a process known as hydrodynamic escape. However, the measurements suggest this process culminated within a few
hundred million years of planetary formation (more than 4 billion years ago), and little change to the atmospheric Xe isotopic
composition has occurred since this time.