onespaceman2000

Study Findings: Early Mars Habitability and Global Cooling by H2-based Methanogens

Posted on October 18, 2022March 5, 2023 by onespaceman2000

^{Image (Credit): Image of present day Mars. (NASA)}

During the Noachian, Mars’ crust may have provided a favourable environment for microbial life. The porous brine-saturated regolith would have created a physical space sheltered from ultraviolet and cosmic radiation and provided a solvent, whereas the below-ground temperature and diffusion of a dense, reduced atmosphere may have supported simple microbial organisms that consumed H₂ and CO₂ as energy and carbon sources and produced methane as a waste. On Earth, hydrogenotrophic methanogenesis was among the earliest metabolisms, but its viability on early Mars has never been quantitatively evaluated. Here we present a probabilistic assessment of Mars’ Noachian habitability to H₂-based methanogens and quantify their biological feedback on Mars’ atmosphere and climate. We find that subsurface habitability was very likely, and limited mainly by the extent of surface ice coverage. Biomass productivity could have been as high as in the early Earth’s ocean. However, the predicted atmospheric composition shift caused by methanogenesis would have triggered a global cooling event, ending potential early warm conditions, compromising surface habitability and forcing the biosphere deep into the Martian crust. Spatial projections of our predictions point to lowland sites at low-to-medium latitudes as good candidates to uncover traces of this early life at or near the surface.

Citation: Sauterey, B., Charnay, B., Affholder, A. et al. Early Mars habitability and global cooling by H₂-based methanogens. Nat Astron (2022). https://doi.org/10.1038/s41550-022-01786-w

Study-related stories:

First Class Fun from the US Post Office

Posted on October 17, 2022January 24, 2024 by onespaceman2000

While the U.S. currency remains pretty boring, at least U.S. postage stamps continually change and highlight various aspects of American society. Two of those themes are science fiction and space exploration, and you have a few options if you want to show your interest in these areas.

These stamps include:

Star Wars Droids (above);
Space Ranger Buzz Lightyear (below); and
James Webb Space Telescope (below).

I know, you hardly ever write letters and you have a bunch of those boring flag stamps. Well, this is your chance to show a little more color on that birthday or anniversary card. Save the flag stamps for the bills.

Be a kid again, if only for a few moments.

Television: Debating Putin’s Nukes

Posted on October 16, 2022 by onespaceman2000

Astrophysicist Neil deGrasse Tyson was a guest on HBO’s Real Time with Bill Maher last Friday. During the broadcast he discussed his new book, Starry Messenger: Cosmic Perspectives on Civilization, which I commented on in an earlier post.

The odd part of the discussion came when Mr. Tyson was trying to explain that hydrogen bombs are not as bad as atomic bombs because they give off less lethal radiation. Bill Maher had earlier expressed his concerns about Russia’s Putin using a nuclear weapon and was surprised to learn that a hydrogen bomb was less dangerous in terms of radiation. He asked about this again, but Mr. Tyson went onto a different topic about the power of conventional arms and never did get back to Mr. Maher’s main concern.

Sadly, Mr. Tyson missed a chance to inform the audience about the dangers of nuclear weapons, be they hydrogen or atomic. As I had noted in an earlier post about nuclear risks, scientists have found that even a limited nuclear exchange can do great damage to the world because of the soot it throws into the upper atmosphere. A Columbia Climate School study on this issue, “Even a Limited India-Pakistan Nuclear War Would Bring Global Famine, Says Study,” found that even 50 Hiroshima-size explosions, which are quite small by today’s standards, would “…launch some 5 million tons of soot toward the stratosphere.” This soot would “…cause production of the world’s four main cereal crops—maize, wheat, soybeans and rice—to plummet an average 11 percent over that period, with tapering effects lasting another five to 10 years.” The impact of famine would lead to the loss of countless lives around the world.

The real risk today is a nuclear winter, which Mr. Tyson never explained. Instead, the audience was left with the impression that a nuclear explosion is not all that serious. Apparently, he was more interested in sharing all of his knowledge about World War II than addressing the question on the table. Mr. Tyson is supposed to be a good science communicator, so he really needs to correct the record. This is no time to be sloppy about nuclear war.

Artemis I: If at First You Don’t Succeed…

Posted on October 15, 2022 by onespaceman2000

NASA is ready to try the uncrewed Artemis I mission again next month. The planned date is November 14, with November 16 and 19 as back up dates.

Should you need it, here is a quick summary of the Artemis I mission again:

Artemis I will be the first integrated flight test of NASA’s deep space exploration system: the Orion spacecraft, Space Launch System (SLS) rocket and the ground systems at Kennedy Space Center in Cape Canaveral, Florida. The first in a series of increasingly complex missions, Artemis I will be an uncrewed flight that will provide a foundation for human deep space exploration, and demonstrate our commitment and capability to extend human existence to the Moon and beyond. During this flight, the uncrewed Orion spacecraft will launch on the most powerful rocket in the world and travel thousands of miles beyond the Moon, farther than any spacecraft built for humans has ever flown, over the course of about a three-week mission.

I am tired of crossing my fingers, so let’s just hope these launch dates work.

^{Image (Credit): Artemis I mission map. (NASA)}

Arecibo Observatory Gone Forever

Posted on October 14, 2022 by onespaceman2000

^{Image (Credit): Matthew McConaughey and Jodie Foster at the Arecibo Observatory in the movie Contact. (Warner Bros.)}

If you were hoping that the Arecibo Observatory in Puerto Rico would have a second life, it may be time to say goodbye. Efforts to rebuild the radio telescope since it collapsed in 2020 have ended. Nature reports that the US National Science Foundation (NSF) has given up on the idea of rebuilding the telescope and instead plans to establish an educational center at the site.

You may have memories from the 1997 film Contact where Matthew McConaughey and Jodie Foster enjoyed some private time at the Observatory. Her character Dr. Ellie Arroway was working at the Observatory as part of the Search for Extraterrestrial Intelligence works (SETI) program. In fact, the SETI connection is true. You can see a SETI tribute to the telescope here.

Of course, scientists will remember almost 60 years of work with the radio telescope. While it was initially built for military purposes, it was soon transformed into a scientific site and served as the largest radio telescope on the planet for some time. As far as scientific accomplishments, here are a few of them from the NSF:

1967: Arecibo discovered that the rotation rate of Mercury is 59 days, not the previously estimated 88 days.
1981: Arecibo produced the first radar maps of the surface of Venus.
1992: Arecibo discovered the first ever exoplanet: In subsequent observations, an entire planetary system was found around the pulsar PSR 1257+12.
2008: Astronomers use Arecibo to detect for the first time, methanimine and hydrogen cyanide molecules — two organic molecules that are key ingredients in forming amino acids — in a galaxy 250 million light-years away.

So many new telescopes have come online in the past 60 years that some will say we will be fine with an educational center. This is true, but it is also worth remembering each of the telescopes along the way that helped us to understand this awesome universe of ours.