Tag Archives: NEAs

Thursday at the non-existent Lunar & Planetary Science Conference

Jezero Crater, under theorized ocean

It is now time for today’s virtual report from the non-existent 51st annual Lunar & Planetary Science conference, cancelled because of the terrified fear of COVID-19.

Unlike the previous three days, the bulk of the abstracts for presentations planned for today are more what I like to call “in-the-weeds” reports. The science is all good, but it is more obscure, the kind of work the scientists will be interested in but will generally hold little interest to the general public. For example, while very important for designing future missions, most of the public (along with myself) is not very interested in modeling studies that improve the interpretation of instrument data.

This does not mean there were no abstracts of interest. On the contrary. For today the most interesting sessions in the conference program centered on Mars as well as research attempting to better track, identify, and study Near Earth asteroids (NEAs).

The map above for example shows the location of Jezero Crater, where the rover Perseverance will land in 2021, under what one abstract [pdf] proposed might have been an intermittent ocean. The dark blue indicates where the topography suggests that ocean might have existed, while also indicating its shoreline. If it existed in the past, Perseverance might thus find evidence of features that were “marine in origin.” This ocean would also help explain the gigantic river-like delta that appears to pour into Jezero Crater from its western highland rim.

There were a lot of other abstracts looking closely at Jezero Crater, all in preparation for the upcoming launch of Perseverance in July, some mapping the site’s geology, others studying comparable sites here on Earth.

Other Mars-related abstracts of interest:
» Read more

Astronomers reduce estimate of still undiscovered dangerous asteroids

Astronomers have now reduced [pdf] their estimate of the number of still undiscovered dangerous Near Earth Asteroids (NEAs) that could impact the Earth from 100 to less than 40.

Observers have been cataloging potentially hazardous asteroids for decades. Based on the number of finds, the area of sky explored, and the limiting brightness our telescopes and cameras can reach, researchers can estimate what fraction of the NEA population has been detected so far and how many more objects lurk undiscovered. Harris has published numerous such estimates over the years. Recently he realized that his estimates have been plagued by a seemingly innocuous but nonetheless consequential round-off error. Once corrected, the estimated number of large (diameter > 1 kilometer) NEAs remaining to be discovered decreases from more than 100 to less than 40.

To put it mildly, there is a lot of uncertainty here. This also reminds me of the cavers’ joke question: “How many miles of unexplored passages does this cave have?”