Lava tubes can be found on planet Earth and the subsurface of the Moon and Mars. Evidence of lava tubes was often inferred by observing linear cavities and sinuous collapse chains where the galleries cracked.
These collapse chains represent ideal gateways or windows for subsurface exploration. The morphological surface expression of lava tubes on Mars and the Moon is similar to their terrestrial counterpart.
A new study by the Universities of Bologna and Padua and its coordinators at Francesco Sauro and Riccardo Pozzobon offers an estimate of the (greater) size of their lunar and Martian counterparts.
Scientists found that lava tubes on Mars and the Moon are so wide they can host planetary bases.
Scientists measured the size and gathered the morphology of lunar and Martian collapse chains (collapsed lava tubes), using digital terrain models (DTMs). The models were obtained through stereoscopic satellite images and laser altimetry taken by interplanetary probes.
They then compared the data to topographic studies about similar collapse chains on the Earth’s surface and laser scans of the inside of lava tubes in Lanzarote and the Galapagos. These data allowed to establish a restriction on the relationship between collapse chains and subsurface cavities that are still intact.
Scientists found that lava tubes on Mars and Moon are respectively 100 and 1,000 times wider than those on Earth.
Riccardo Pozzobon said, “Tubes as wide as these can be longer than 40 kilometers, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes. The latter are so big they can contain Padua’s entire city center.”
Matteo Massironi, who is professor of Structural and Planetary Geology at the Department of Geosciences of the University of Padua said, “What is most important is that, despite the impressive dimension of the lunar tubes, they remain well within the roof stability threshold because of a lower gravitational attraction.”
“This means that the majority of lava tubes underneath the maria smooth plains are intact. The collapse chains we observed might have been caused by asteroids piercing the tube walls. This is what the collapse chains in Marius Hills seem to suggest. From the latter, we can get access to these huge underground cavities.”
Francesco Sauro concludes: “Lava tubes could provide stable shields from cosmic and solar radiation and micrometeorite impacts that are often happening on planetary bodies’ surfaces. Moreover, they have great potential to provide an environment in which temperatures do not vary from day to night. Space agencies are now interested in planetary caves and lava tubes, as they represent the first step towards future explorations of the lunar surface (see also NASA’s project Artemis) and towards finding life (past or present) in Mars subsurface.”
Scientists noted, “this study opens up to a completely new perspective in planetary exploration, which is increasingly focusing on the subsurface of Mars and the Moon.”
- Francesco Sauro et al. Lava tubes on Earth, Moon, and Mars: A review on their size and morphology revealed by comparative planetology. DOI: 10.1016/j.earscirev.2020.103288
New Brunswick reports one new case of COVID-19, has four active cases – Yahoo News Canada
FREDERICTON — New Brunswick is reporting one new case of COVID-19 today.
Health officials say the new case involves an individual between 60 and 69 years old in the Miramichi region.
They say the case is related to travel from outside of the Atlantic bubble and the person is self-isolating.
There have been 197 confirmed cases of the novel coronavirus in New Brunswick to date, and 191 people have recovered.
Two people have died, and four cases are still active.
Health officials have conducted a total of 71,585 tests.
This report by The Canadian Press was first published Sept. 23, 2020.
The Canadian Press
Newly-discovered asteroid buzzes past Earth Thursday morning – The Weather Network
Astronomers are tracking a newfound asteroid that is expected to make a brief but very close pass by Earth, early Thursday morning.
Asteroid 2020 SW was discovered on September 18, by the Catalina Sky Survey in Arizona. Estimated at between 5 to 10 metres wide, this space rock will make its closest pass by Earth at 7:12 a.m. EDT, on Thursday, September 24.
At that time, it is expected to be roughly 22,000 kilometres above the planet’s surface.
“There are a large number of tiny asteroids like this one, and several of them approach our planet as close as this several times every year,” Paul Chodas, director of the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory, said in a press release on Wednesday. “In fact, asteroids of this size impact our atmosphere at an average rate of about once every year or two.”
This frame from the NASA asteroid trajectory animation shows 2020 SW at its closest approach to Earth. Credit: NASA JPL
At that distance, the asteroid is actually closer than the ring of geostationary weather and communications satellites surrounding Earth at a distance of around 36,000 kilometres. However, as the image above shows, by then, the asteroid will be below the satellite ring and beneath Earth.
Although 2020 SW is logged as a “potentially hazardous asteroid” in NASA’s records, it doesn’t pose any threat to Earth. According to CNEOS, who has traced the asteroid’s orbit back to 1975 and forward to 2095, this September 24 pass is the closest this object has ever come to us in that timespan.
The shape of asteroid 2020 SW’s 373-day orbit around the Sun marks it as an Apollo asteroid – an Earth-crossing asteroid that spends all of its time between the orbits of Venus and Mars. Credit: NASA CNEOS
The next time the asteroid will be anywhere close to Earth again is in September of 2041. At that time, it will be pass far beyond the Moon, at a distance of over 3.5 million kilometres.
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While 2020 SW poses no threat to Earth, it is still of interest to scientists. NASA’s Goldstone Observatory is planning to bounce radio waves off the asteroid’s surface during this close pass. The data collected can then be turned into radar images, revealing the asteroid’s shape and giving us an idea of its composition.
The 34-meter DSS-13 radio antenna at the Goldstone Observatory is used for radio astronomy, including collecting radar images of passing near-Earth objects. Credit: NASA
According to NASA, if 2020 SW or an asteroid of similar size did actually strike Earth, it would almost certainly break apart high up in the atmosphere as a fireball. Only the toughest space rocks of this size – those primarily composed of metal – can reach the surface mostly intact.
“The detection capabilities of NASA’s asteroid surveys are continually improving,” added Chodas, “and we should now expect to find asteroids of this size a couple days before they come near our planet.”
Indeed, the fact that this tiny rock was spotted roughly six days before its flyby is a testament to the Catalina Sky Survey’s asteroid detection skills.
Reptile dubbed 'Jaws of Death' terrorized Cretaceous seas – CANOE
Article content continued
“If you were an animal in the oceans less than 20 feet (6 metres) in length, you are most likely on the menu for Gnathomortis,” added Lively, whose study was published in the Journal of Vertebrate Paleontology.
That menu, Lively said, may have included sea turtles, fish, sharks and other marine reptiles including smaller mosasaurs.
Like other mosasaurs and many lizards and snakes, it boasted an extra set of teeth on the roof of its mouth.
A large depression on the outer surface of its lower jaws is indicative of large muscles that gave it tremendous bite-force. While it lived alongside even-larger mosasaurs like 46-foot-long (14-metre-long) Tylosaurus in the Western Interior Seaway that ran from present-day Canada to Mexico, Gnathomortis had stronger jaws.
“‘Jaws of Death’ seemed appropriate for this kind of critter,” Lively said, “and it turns out to be an awesome name.”
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