Could a Supernova Have Wiped Out the Martian Atmosphere?

Did high energy astrophysical sources contribute to Martian atmospheric loss?

Authors:

Atri et al

Abstract:

Mars is believed to have had a substantial atmosphere in the past. Atmospheric loss led to depressurization and cooling, and is thought to be the primary driving force responsible for the loss of liquid water from its surface. Recently, MAVEN observations have provided new insight into the physics of atmospheric loss induced by ICMEs and solar wind interacting with the Martian atmosphere. In addition to solar radiation, it is likely that its atmosphere has been exposed to radiation bursts from high-energy astrophysical sources which become highly probable on timescales of ~Gy and beyond. These sources are capable of significantly enhancing the rates of photoionization and charged particle-induced ionization in the upper atmosphere. Here, we explore the possibility of damage from Galactic Gamma Ray Bursts, nearby supernovae, encounter with dense interstellar clouds and extreme solar events. We use Monte Carlo simulations to model the interaction of charged particles and photons from astrophysical sources in the upper Martian atmosphere and discuss its implications on atmospheric loss.

What Were the The 774 and 993 AD Radiation Events

In the years 774 and 993 AD, the Earth was attacked from space.

Not by aliens, but by a natural event — and it was very, very powerful.

Whatever it was, it subtly altered the chemistry of our planet’s atmosphere, creating trace amounts of radioactive elements like chlorine-36, beryllium-10, and carbon-14. And those provide the clue to what the event was: Those isotopes are created when high-energy protons slam into our air. That means the source must have been from space.

These must have been huge waves of subatomic particles that slammed into us on those dates. Spikes in the abundances of those elements were found all over the world, including ice cores from the Arctic and Antarctic, Chinese corals, and more. Generating that many particles isn’t easy, and only extremely violent events can do it.

Several possible sources have been considered. One candidate is that the Earth got caught in the beam from a gamma-ray burst, the mind-crushingly powerful demise of a very high mass star. I wrote about this being the possible cause of the 774 event in an earlier article. However, GRB impacts don’t usually create 10Be due to the detailed physics of the blast, so that makes a GRB as the source shaky. Plus, they’re very rare events, so having two happen in as many centuries is extremely unlikely (I didn’t know about the 993 AD event when I wrote that article, or else I would’ve been a lot more likely to wonder about other sources).

New research studying the amounts of these radioactive materials in ice cores points to a different culprit, one I wouldn’t have thought possible: the Sun.

link.

Extraordinary Claim: A Gamma Ray Burst CAUSED the Cambrian Explosion?!

Did Gamma Ray Burst Induce Cambrian Explosion?

Authors:

Chen et al

Abstract:

One longstanding mystery in bio-evolution since Darwin's time is the origin of the Cambrian explosion that happened around 540 million years ago (Mya), where an extremely rapid increase of species occurred. Here we suggest that a nearby GRB event ~500 parsecs away, which should occur about once per 5 Gy, might have triggered the Cambrian explosion. Due to a relatively lower cross section and the conservation of photon number in Compton scattering, a substantial fraction of the GRB photons can reach the sea level and would induce DNA mutations in organisms protected by a shallow layer of water or soil, thus expediting the bio-diversification. This possibility of inducing genetic mutations is unique among all candidate sources for major incidents in the history of bio-evolution. A possible evidence would be the anomalous abundance of certain nuclear isotopes with long half-lives transmuted by the GRB photons in geological records from the Cambrian period. Our notion also imposes constraints on the evolution of exoplanet organisms and the migration of panspermia.