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Earth Trojan asteroid will share an orbit with us for 4,000 years

Astronomers have discovered that Earth has a second Trojan asteroid lurking in our orbit, and say it will remain in position for at least another 4,000 years, making it a great candidate for future fly-by missions.

Trojan asteroids are small bodies that share the same orbit as a planet. They remain in a stable orbit because the gravitational force of the Sun and Earth on the asteroid are balanced, and they travel approximately 60° ahead of or behind the main body – in this case, Earth.

This asteroid, called 2020 XL5, was first discovered in in 2020 but was only recently confirmed to be an Earth Trojan asteroid by combining archival data and observations from three ground-based observatories.

It was reported in a study published in Nature Communications, which also proposes that it is a C-complex type asteroid – that is, predominantly composed of carbon – and may have been ejected from the main asteroid belt after an interaction with Jupiter.

An armoured mistfrog sits on a multicoloured rock
The Critically Endangered Armoured Mistfrog is found only in Queensland’s Wet Tropics. Credit: Conrad Hoskin

Genetic clues could help us find Australia’s ‘missing’ frogs

For decades, scientists have been scouring remote mountain ranges in Australia in search of critically endangered frog species that have vanished from the wild. New research published in PeerJ could revolutionise the search, showing it’s possible to find traces of a frog’s environmental DNA (eDNA) in catchments over 20 kilometres downstream from their habitats.

“When frogs visit water streams they shed bits of their genetic material, such as skin, urine, saliva, faeces and blood into the water,” says Dr Cecilia Villacorta-Rath, co-lead author from James Cook University’ Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), Australia.

“This eDNA travels kilometres downstream to feed into a bigger catchment – and this is where we could detect even small populations.

“It’s a remarkable result. We could find where these missing frogs are hiding, without even sighting them.”

The research team used this new tool on a known armoured mist frog population living in the mountains outside of Cairns, but it could also be used to track down potential remnant populations of frogs that have gone missing.

Martian meteorite gives insight into when Mars might have been habitable

Researchers studying a Martian meteorite have found the first evidence of high-intensity damage caused by asteroid impact on Mars. This suggests that the potential window of habitability on Mars may have occurred later than previously thought.

Designated northwest africa nwa 7034 and nicknamed black beauty this martian meteorite weighs approximately 11 ounces 320 grams. Nasa
Designated Northwest Africa (NWA) 7034, and nicknamed Black Beauty, this Martian meteorite weighs approximately 320 grams. Credit: NASA

Scientists studied tiny grains of the mineral zircon within the meteorite NWA 7034, also nicknamed ‘Black Beauty’, which was found in Africa in 2013. These grains displayed microscopic damage, caused by shock waves from a large impact that hit the zircons while they were still on Mars, before they were mixed into the meteorite that eventually made it to Earth.

“This grain is truly a one-off gift from the Red Planet,” says lead author Morgan Cox, PhD candidate at Curtin University’s Space Science and Technology Centre (SSTC) in Australia. “High-pressure shock deformation has not previously been found in any minerals from Black Beauty. This discovery of shock damage in a 4.45 billion-year-old Martian zircon provides new evidence of dynamic processes that affected the surface of early Mars.”

This type of shock damage has been recorded in many of the biggest meteorite impacts on Earth, including the one that killed off the dinosaurs – but never before in a Martian meteorite.

It’s dated to around 4.45 billion years ago, which suggests that the Martian surface was being bombarded by large asteroids at that time, making it unsuitable for life to develop. This therefore pushes back the window in which Mars could have been habitable.

The study was published in Science Advances.

The abyss is more biologically diverse than we knew

Despite covering more than 60% of the Earth, the deep-ocean floor is the least explored ecosystem on the planet. These deep ecosystems underpin the healthy functioning of the ocean food-webs – and the burial of carbon on vast geological timescales – and yet their biodiversity is not well understood.

For the first time, researchers have obtained a unified picture of the full ocean diversity by sequencing the DNA contained in deep-sea sediments from all major oceanic basins. As described in a study published in Science Advances, they took nearly 1700 samples, resulting in two billion DNA sequences from the surface to the deep-ocean floor worldwide.

The team compared the ocean-floor DNA sequences to ones from the open ocean, and found that biodiversity on the seabed could be three times as large as in the water masses above. Interestingly, the DNA from the ocean floor was composed of mostly unknown species – highlighting a major gap in our knowledge of marine biodiversity.

“Huge numbers of unknown organisms inhabit ocean-floor sediments and must play a fundamental role in ecological and biogeochemical processes,” says co-author Professor Andrew J. Gooday of the National Oceanography Centre, UK. “A better knowledge of this rich diversity is crucial if we are to protect these vast, relatively pristine ecosystems from the impacts of possible future human incursions and understand the effects on it of climate change.”

A ship floats between sea ice in the arctic ocean
An effort of 15 deep-sea international expeditions has allowed the analysis of abyssal sediments collected in all major oceanic regions, including the Arctic and Southern Oceans. Credit: Andreas Worden

Most preprints are reliable and trustworthy

Preprinting – the sharing of freely available manuscripts prior to peer-review – has surged during the COVID-19 pandemic to speed up the distribution of timely research.

There have been concerns over the quality of preprints, but two new studies published in PLOS Biology support the reliability and use of preprints, both during the global pandemic and for general scientific outputs.

One study, comparing preprints to their published versions in the first four months of the COVID-19 pandemic, found that over 83% of COVID and 93% of non-COVID-related life sciences articles do not change from their preprint to final published versions.

The other used machine learning to compare 18,000 published papers with their preprints in the bioRxiv library, an open access preprint repository for the biological sciences. The study found that most differences appear to occur from typesetting and the addition of supplementary materials, rather than from a change in content.

“Examining preprint-publication pairs provides an opportunity to study the process of peer review and taken together our results should provoke a rethinking of the role and prominence of peer-review in the current publication system,” says Dr Casey Greene of the University of Colorado School of Medicine, US, who was a co-author on the second study.

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