Potentially hazardous asteroid Bennu just became slightly more potentially dangerous.
Over a century from now, in 2135, a half-kilometre-wide asteroid named 101955 Bennu will pass between the Earth and the Moon. While there is absolutely no chance of an impact with Bennu at that time, the close encounter throws uncertainty into the predictions. As a result, there’s no saying for sure that Earth will be safe from Bennu afterward.
Before NASA sent their OSIRIS-REx spacecraft to Bennu, astronomers tracked asteroid Bennu using telescopes. Their observations gave us very accurate calculations of Bennu’s orbit. The relatively close passes of Bennu in 1999, 2005 and 2011 helped with this. Although it was officially classified as a “Potentially Hazardous Asteroid” (PHA), NASA could rule out any possibility of a Bennu impact for the next 100+ years.
However, the September 2135 encounter added an extra complication. The asteroid comes very close to Earth at that time. On September 24 of that year, its absolute minimum distance could be around 110,000 km from the planet’s surface or less than one-third the distance to the Moon. As it flies past, it will encounter one of several ‘gravitational keyholes’. As it passes through one of these tiny points in space, Earth’s gravity will tug on the asteroid and alter its orbit around the Sun.
This screenshot of an animation used during the NASA press briefing on Wednesday, August 11, 2021, shows the potential paths of Bennu during the 2135 flyby, based on the most up-to-date telescope observations, with a separate ‘gravitational keyhole’ for each path. Credit: NASA/Goddard
Even with the carefully plotted orbit of Bennu, the minor uncertainties made it challenging to tell which ‘keyhole’ it would pass through during that 2135 flyby. Thus, there was no way to know with any certainty which orbit it would end up on afterward.
This was of great concern to scientists because it introduced over 150 possible impacts, with a cumulative 1 in 2,700 impact chance between 2135 and 2300. The most likely impact would be on September 24, 2182.
The effects of one particular ‘gravitational keyhole’ could have disastrous results in 2182. Credit: NASA/Goddard
With OSIRIS-REx following along with the asteroid for over two years, though, it gave scientists an unprecedented chance to closely track the influence of the Yarkovsky effect.
The Yarkovsky effect is a tiny, constant ‘push’ that an asteroid receives as it radiates heat into space.
Watch below: How the Sun pushes asteroids around the solar system
According to Davide Farnocchia from the Center for Near Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Lab, who is the lead author of a new study published this week, the force of this ‘push’ on Bennu is equivalent to about the weight of three grapes.
“Think about that, just three grapes,” Farnocchia said in a NASA teleconference on Wednesday. “Because this acceleration is persistent, its effect builds up over time, and it becomes very significant by the time we get to 2135.”
“The OSIRIS-REx data give us so much more precise information, we can test the limits of our models and calculate the future trajectory of Bennu to a very high degree of certainty through 2135,” Farnocchia said in a NASA press release. “We’ve never modelled an asteroid’s trajectory to this precision before.”
Based on their study of the Yarkovsky effect on Bennu, Farnocchia and his colleagues calculated an updated cumulative probability of a Bennu impact between 2135 and 2200. Instead of 1 in 2,700, the chance is now just 1 in 1,750. The individual chance of an impact on September 24, 2182, is now 1 in 2,700.
It should be noted that these probabilities are tiny.
A 1 in 1,750 chance is equal to a 0.057 per cent impact probability, while 1 in 2,700 is equivalent to 0.037 per cent. That means there’s over a 99.94 per cent chance that Bennu will miss Earth on all the potential encounters it has towards the end of the 22nd century. Specifically for September 2182, there’s a 99.96 per cent chance of a miss.
During their research, Farnocchia and the others accounted for every conceivable force that could affect Bennu’s orbit. They even considered whether the Touch-and-Go (TAG) maneuver that netted NASA a sample of the asteroid was enough to alter its trajectory.
Watch below: NASA’s OSIRIS-REx tags asteroid Bennu
“The force exerted on Bennu’s surface during the TAG event were tiny even in comparison to the effects of other small forces considered,” Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center, said in the press release. “TAG did not alter Bennu’s likelihood of impacting Earth.”
The next steps in determining Bennu’s true potential as a threat to Earth will come in 2023 and 2037.
In 2023, OSIRIS-REx will swing past Earth. On its way past, it will drop off the sample it collected from Bennu’s surface back in the Fall of 2020. As scientists examine these samples in the laboratory, we will learn more about Bennu’s composition. This might provide information about how we could deflect such an asteroid on an impact trajectory.
In 2037, Bennu will be making its next close (but safe) flyby past Earth. During this pass, radio telescopes can gather radar data on the asteroid. These readings will help confirm the calculations made based on OSIRIS-REx’s data and give us an even better estimate of its exact path for that 2135 encounter.
SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space – Californianewstimes.com
Give a few seconds (or a minute or two if needed) to startle and gaze at the Earth’s scenery from the recently launched SpaceX Crew Dragon above.
on Wednesday,Tied to the SpaceX Crew Dragon with one of the upgrades: Cupola. The transparent dome at the top of the Dragon Capsule provides the Inspiration 4 crew with the best views of the Earth that up-and-coming astronauts can dream of. This is the first time a cupola has been installed on a dragon. Dragons typically carry astronauts and cargo to the ISS, with docking ports at the top instead of windows.
A short video posted to the SpaceX Twitter account hours after the launch shows the cupola’s transparent dome against the Earth, which is a pale blue marble.
As the Crew Dragon orbits from a height of 585 kilometers (more than 360 miles), our planet is exposed to the sun and slowly roams around the orbs.
Inspiration 4’s crew (commander Jared Isaacman, doctor’s assistant, childhood cancer survivor Haley Arseno, aerospace engineer Chris Sembroski, African-American geology professor Sian Proctor) are in orbit for three days. Ride and stare at the cupola and the earth.
And did you say that the cupola is right next to the dragon’s toilet? Yeah, the view of the earth should be visible from the crew dragon’s bathroom. Isaacman told insiders Toilets are one of the few places where you can separate yourself from others with privacy curtains and have the best toilet windows of mankind. “When people inevitably have to use the bathroom, they will see one view of hell,” he said.
Astronauts who have been to space often talk about a phenomenon called the “overview effect.” Looking at the planet from above, the idea is that the way we think about the planet and the mass of humankind that depends on it will change. There may be a lot of revelation at the end of the Inspiration 4 journey, as I don’t know if they thought of it while sitting in the can.
The mission is the first mission to take off from the Florida coast on Wednesday night and be launched with four civilians. It is expected to return to Earth on Saturday and land in the Atlantic Ocean.
SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space Source link SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space
Oldest human footprints in North America found in New Mexico – Al Jazeera English
Fossilised footprints dating 23,000 years push back the known date the continent was colonised by thousands of years.
Footprints dating back 23,000 years have been discovered in the United States, suggesting humans settled North America long before the end of the last Ice Age, according to researchers.
The findings announced on Thursday push back the date at which the continent was colonised by its first inhabitants by thousands of years.
The footprints were left in mud on the banks of a long-since dried up lake, which is now part of a New Mexico desert.
Sediment filled the indentations and hardened into rock, protecting evidence of our ancient relatives, and giving scientists a detailed insight into their lives.
The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists at the United States Geological Survey recently analysed seeds stuck in the footprints to determine their approximate age, ranging from 22,800 to 21,130 years ago.
“Many tracks appear to be those of teenagers and children; large adult footprints are less frequent,” write the authors of the study published in the American journal Science.
“One hypothesis for this is the division of labour, in which adults are involved in skilled tasks whereas ‘fetching and carrying’ are delegated to teenagers.
“Children accompany the teenagers, and collectively they leave a higher number of footprints.”
Researchers also found tracks left by mammoths, prehistoric wolves, and even giant sloths, which appear to have been approximately at the same time as the humans visited the lake.
The Americas were the last continent to be reached by humanity.
For decades, the most commonly accepted theory has been that settlers came to North America from eastern Siberia across a land bridge – the present-day Bering Strait.
From Alaska, they headed south to kinder climes.
Archaeological evidence, including spearheads used to kill mammoths, has long suggested a 13,500-year-old settlement associated with so-called Clovis culture – named after a town in New Mexico.
This was considered the continent’s first civilisation, and the forerunner of groups that became known as Native Americans.
However, the notion of Clovis culture has been challenged over the past 20 years, with new discoveries that have pushed back the age of the first settlements.
Generally, even this pushed-back estimate of the age of the first settlements had not been more than 16,000 years, after the end of the so-called “last glacial maximum” – the period when ice sheets were at their most widespread.
This episode, which lasted until about 20,000 years ago, is crucial because it is believed that with ice covering much of the northern parts of the continent, human migration from Asia into North America and beyond would have been very difficult.
Oldest human footprints in North America found in New Mexico – CTV News
Fossilized footprints discovered in New Mexico indicate that early humans were walking across North America around 23,000 years ago, researchers reported Thursday.
The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists at the U.S. Geological Survey recently analyzed seeds stuck in the footprints to determine their approximate age, ranging from around 22,800 and 21,130 years ago.
The findings may shed light on a mystery that has long intrigued scientists: When did people first arrive in the Americas, after dispersing from Africa and Asia?
Most scientists believe ancient migration came by way of a now-submerged land bridge that connected Asia to Alaska. Based on various evidence — including stone tools, fossil bones and genetic analysis — other researchers have offered a range of possible dates for human arrival in the Americas, from 13,000 to 26,000 years ago or more.
The current study provides a more solid baseline for when humans definitely were in North America, although they could have arrived even earlier, the authors say. Fossil footprints are more indisputable and direct evidence than “cultural artifacts, modified bones, or other more conventional fossils,” they wrote in the journal Science, which published the study Thursday.
“What we present here is evidence of a firm time and location,” they said.
Based on the size of the footprints, researchers believe that at least some were made by children and teenagers who lived during the last ice age.
David Bustos, the park’s resource program manager, spotted the first footprints in ancient wetlands in 2009. He and others found more in the park over the years.
“We knew they were old, but we had no way to date the prints before we discovered some with (seeds) on top,” he said Thursday.
Made of fine silt and clay, the footprints are fragile, so the researchers had to work quickly to gather samples, Bustos said.
“The only way we can save them is to record them — to take a lot of photos and make 3D models,” he said.
Earlier excavations in White Sands National Park have uncovered fossilized tracks left by a saber-toothed cat, dire wolf, Columbian mammoth and other ice age animals.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
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