At https://phys.org/news/2023-10-potentially-hazardous-city-killing-asteroids-left.html … a NASA subsidiary released, on October 16th, an infograph that shows the current state of ‘Planetary Defense’ in their ongoing search for Near Earth objects that cross the orbit of the earth. Asteroids do not emit light. They are dark objects unless they can be detected when sunlight reflects off their surfaces. Currently, 32,000 space rocks have been catalogued – more than 10,000 of which are more than 140m across. If one of these hit the earth, or exploded in the atmosphere, relatively close to the surface, it would be capable of wiping out a modern city. In comparison, the Chelyabinsk meteor in 2013, was just 20m across – and it exploded high in the atmosphere with the shock wave dissipated into thin air. Nevertheless it still managed to do a bit of damage at the surface. A space rock seven times as big, a 140m size, would penetrate deeper into the atmosphere – closer to the surface. That is the potential danger uncovered. It is then estimated there are now more than 14,000 140m diameter space rocks out there yet to be catalogued and their actual orbits recorded. How close they might come in the future to the planet. There are also estimated to be, among that number, 50 1km across space rocks yet to be found. The dinosaur killing asteroid was 10km across – so the end of the world is not anticipated.
At https://spaceweather.com [see the archive for October 1st 2023]. It seems meteors left behind by the passage of Comet Halley in the past, the so called Orionids, still interact with the atmosphere of the earth, thousands of years afterwards. We also learn that an earth to sky baloon, released by a team associated with Space Weather, landed back on earth in 2022. These baloons are designed to monitor radiation levels in the upper atmosphere and the data is added month by month. The baloon in question landed in a difficult to access location, last year, in the mountains of the Sierra Nevada in California. Not only that it was warm and dry at the time – hardly any rain for a couple of years. It landed in a spread of snow melt on a mountain side. This had been a glacier but because of the lack of rain, the glacier was not being replenished with fresh ice in the winters. The remains were therefore exposed more and more to the effects of the sun – by melting at the surface. In other words, the baloon landed in a puddle of water on the glacier surface. A big puddle no doubt, but basically a puddle of water at the top of the glacier. Unfortunately for the people wishing to retrieve their baloon, last winter it was wet in California and the object is now within frozen ice, the puddle having become part of the glacier once again. In spite of global boiling last year.
Finally, at https://phys.org/news/2023-10-nasa-voyager-team-focuses-software.html …. engineers from NASAs Voyager mission are hoping to make sure both Voyager 1 and 2 spacecraft, launched in 1977, will continue to beam back information in the coming years – by upgrading the software with a patch.