Connect with us

Science

New study finds the Universe has less dark energy than previously theorized

Published

 on

The makeup and the growth of the Universe have never been clearer — or as confusing — as they’ve been revealed to be in a massive new survey of the markers astronomers use to measure the cosmos.

A new analysis called Pantheon+ has narrowed down the uncertainty in the expansion and makeup of the Universe. To do this, Pantheon+ builds on two long-standing astronomical projects — one called Pantheon, combining observations of 1,550 supernovae reaching back 10 billion years; and another called SH0ES, which measures relatively close pulsing stars known as Cepheids within 10 million light years.

The Pantheon+ analysis of the makeup and expansion of the Universe published recently in The Astrophysical Journal finds that 66.2 percent of the Universe is made up of dark energy, the mysterious accelerator driving the Universe’s speeding expansion, slightly less than past estimates of about 68 percent.

Only 33.8 percent of the Universe is matter — and the vast majority of that is impossible-to-observe dark matter, whose existence astronomers can only infer from galactic-scale gravitational effects. At the accepted rate of 85 percent dark matter to 15 percent normal (baryonic) matter, that means just slightly less than 5 percent of the mass of the Universe is the stuff we can see around us.

Genius Dog 336 x 280 - Animated

Pantheon+ was also able to measure the Universe’s expansion to within 1.3 percent uncertainty, close enough that it is now undeniable that the early Universe and the current Universe don’t expand at the same pace.

Speaking with Inverse, lead author Dillon Brout, a NASA Einstein fellow at the Center for Astrophysics | Harvard-Smithsonian, says that this degree of precision means that instead of being limited by the data for measuring the growth of the Universe, “we’re approaching the limit where we’re limited by the uncertainties of our method.”

WHAT’S NEW — Pantheon+ offers as precise a measurement of dark energy, dark matter, and baryonic matter as can currently be assembled.

And “assembled” is the right word — this work combines analysis from the original Pantheon, which measured dark matter, and the Supernova H0 for the Equation of State (SH0ES), which measures the Hubble constant at which the Universe expands.

Pantheon+ synthesizes two decades of data from different telescopes and astronomers into a single analysis; it represents “an all-star sample,” Brout explains. And this is the biggest set of exploding stars that have been put together — over 1500, half again as many as an earlier version that focused just on the supernovae.

But Brout notes that’s about all that can be gained with current equipment. The limiting factor is time. “We get about one supernova per year that helps us measure the Hubble constant, and we’ve got 42 of them now. So we’re going to have to wait a while just to double our data set,” he says.

The cosmic microwave background is one of the best ways to understand the early universe. Print Collector/Hulton Archive/Getty Images

WHY IT MATTERS — Surveys like Pantheon+ allow astronomers to cross-check their results across different methods and different targets. Some components measure Cepheids, relatively nearby stars whose brightness waxes and wanes regularly; others measure supernovae who outshone galaxies up to 10 billion years ago.

For the time being, this is about as accurate as these kinds of measurements can get. “A lot of people will think ‘of course, you have to use James Webb,’” says Brout, “and the answer to that is ‘yes’ — but it’s not immediately clear how much it’s going to help us.” The James Webb Space Telescope will let astronomers look at the ways stellar dust and observations in different wavelengths impact observations of the anchors that hold their measurements in place.

The increasing accuracy of this analysis has also increased one of the biggest problems in cosmology. Pantheon+ has narrowed down the speed at which the Universe is expanding to 73.4 kilometers per second per megaparsec — give or take 1.3 percent. This means that, locally, space is getting bigger at about 164,000 miles per hour.

But that’s just here and, more importantly, now. Measurements of the cosmic microwave background show that in its earliest days, the Universe was definitely expanding slower, about 67 kilometers per second per megaparsec. As surveys like Pantheon+ get more accurate, it gets clearer and clearer that this discrepancy — the Hubble tension — can’t just be explained away by the difficulty of getting clear observations.

The Universe’s expansion has undeniably sped up, but it’s not quite clear why.

WHAT’S NEXT — As an overview of the field, Brout notes Pantheon+ is a way of capturing the state of the art right before an enormous transformation. Over the next two years, the Vera Rubin Observatory in Chile will come on line, and “the game is going to kind of change in the future.”

While work measuring dark matter, dark energy, and the expansion of the cosmos have been built on many different observations with many different tools, “going forward we have these big, billion-dollar telescopes that are collecting really enormous samples on their own.”

How enormous? The Rubin Observatory expects to find over a million of the right kind of ancient supernovae in the next dozen years – a thousand times more than what Pantheon+ collates.

The scale of the teams working on this data will change, too: “these are going to be huge collaborations with hundreds of people and they’re going to nail a lot of these things down.” But for now, “before these really big giant telescopes turn on,” Brout hopes Pantheon+ can be the apex of an era.

Source link

Continue Reading

Science

NASA Artemis I – Flight Day 22: Orion Spacecraft Continues Its Journey Back to Earth – SciTechDaily

Published

 on



On flight day 20, Orion captured the crescent Earth in the distance as the spacecraft regained communications with the Deep Space Network following its return powered flyby on the far side of the Moon. The spacecraft will splash down on Sunday, December 11. Credit: <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

NASA
Established in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is &quot;To discover and expand knowledge for the benefit of humanity.&quot; Its core values are &quot;safety, integrity, teamwork, excellence, and inclusion.&quot;

” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>NASA

Genius Dog 336 x 280 - Animated

On day 22 of the 25.5-day Artemis I mission, the Orion spacecraft continues its journey back to Earth. Flight controllers and engineers continue to test the spacecraft and its systems in preparation for future flights with a human crew aboard.

The second part of the propellant tank slosh development flight test was conducted by engineers. This propellant slosh test is specifically scheduled during quiescent, or less active, parts of the mission. Propellant motion, or slosh, in space is difficult to model on Earth because, due to the lack of gravity, liquid propellant moves differently in tanks in space than on Earth.


On flight day 20, Orion approached the Moon ahead of the return powered flyby burn that committed the spacecraft to splashdown on Sunday, December 11. Credit: NASA

For the test, flight controllers need to fire the reaction control system thrusters when propellant tanks are filled to different levels. The reaction control thrusters used are located on the sides of the service module and can be fired individually as needed to move the spacecraft in different directions or rotate it into any position. Each of these engines provides about 50 pounds of thrust. Engineers measure the effect the propellant sloshing has on spacecraft trajectory and orientation as Orion moves through space.

The test was first performed after the outbound flyby burn, and now again after the return flyby burn, to compare data at points in the mission with different levels of propellant onboard. Approximately 12,060 pounds of propellant has been used, which is 215 pounds less than estimated prelaunch, and leaves a margin of 2,185 pounds over what is planned for use, 275 pounds more than prelaunch expectations. The first prop slosh test objective was completed on day eight of the mission as Orion prepared to enter the distant retrograde orbit.


On flight day 20, Orion approached the Moon ahead of the return powered flyby burn that committed the spacecraft to splashdown on Sunday, December 11. Credit: NASA

A few key milestones for Orion remain, including the entry system checkouts and propulsion system leak checks on mission days 24 and 25, respectively.

Orion will travel at around 25,000 mph (40,000 km/h) while reentering Earth’s atmosphere, testing the world’s largest ablative heat shield by reaching temperatures up to 5,000 degrees <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

Fahrenheit
The Fahrenheit scale is a temperature scale, named after the German physicist Daniel Gabriel Fahrenheit and based on one he proposed in 1724. In the Fahrenheit temperature scale, the freezing point of water freezes is 32 °F and water boils at 212 °F, a 180 °F separation, as defined at sea level and standard atmospheric pressure.&nbsp;

” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>Fahrenheit (2,800 degrees <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

Celsius
The Celsius scale, also known as the centigrade scale, is a temperature scale named after the Swedish astronomer Anders Celsius. In the Celsius scale, 0 °C is the freezing point of water and 100 °C is the boiling point of water at 1 atm pressure.

” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>Celsius) – approximately half the temperature of the surface of the sun. The heat shield is located at the bottom of the Orion capsule, measuring 16.5 feet (5 meters) in diameter, and sheds intense heat away from the crew module as Orion returns to Earth. The outer surface of the heat shield is made of 186 billets, or blocks, of an ablative material called Avcoat, a reformulated version of the material used on the Apollo capsules. During descent, the Avcoat ablates, or burns off in a controlled fashion, transporting heat away from Orion. Learn more about Orion’s heat shield in the Artemis I reference guide.


Artemis All Access is your look at the latest in Artemis I, the people and technology behind the mission, and what is coming up next. This uncrewed flight test around the Moon will pave the way for a crewed flight test and future human lunar exploration as part of Artemis. Credit: NASA

On Thursday, December 8 at 5 p.m. EST, NASA will host a briefing to preview Orion’s return scheduled for Sunday, December 11 and to discuss how the recovery teams are preparing for entry and splashdown. The briefing will be live on NASA TV, the agency’s website, and the NASA app.

Watch the latest episode of Artemis All Access (video embedded above) for a look back at recent mission accomplishments and a preview of splashdown, including parachute information.

Adblock test (Why?)



Source link

Continue Reading

Science

Discovery Of World's Oldest DNA Breaks Record By One Million Years – Forbes

Published

 on


Microscopic fragments of DNA were found in Ice Age sediment in northern Greenland. Using cutting-edge technology, researchers discovered the fragments are one million years older than the previous record for DNA sampled from a Siberian mammoth bone.

The discovery was made by a team of scientists led by Professor Eske Willerslev and Professor Kurt H. Kjær. Professor Willerslev is a Fellow of St John’s College, University of Cambridge, and Director of the Lundbeck Foundation GeoGenetics Center at the University of Copenhagen where Professor Kjær, a geology expert, is also based.

“A new chapter spanning one million extra years of history has finally been opened and for the first time we can look directly at the DNA of a past ecosystem that far back in time,” so Professor Willerslev commenting the discovery.

Genius Dog 336 x 280 - Animated

“DNA can degrade quickly but we’ve shown that under the right circumstances, we can now go back further in time than anyone could have dared imagine.”

Professor Kjær adds that “the ancient DNA samples were found buried deep in sediment that had built-up over 20,000 years. The sediment was eventually preserved in ice or permafrost and, crucially, not disturbed by humans for two million years.”

The incomplete samples, a few millionths of a millimeter long DNA strings, were taken from the København Formation, a sediment formation almost 100 meters thick deposited in the shallow area of a fjord in Greenland’s northernmost point. The climate in Greenland at the time of sedimentation was between 10 to 17 degrees warmer than today, sustaining an ecosystem with no present-day equivalent, resembling a mix of temperate forest and mixed-grass prairie.

Detective work by 40 researchers from Denmark, the UK, France, Sweden, Norway, the U.S. and Germany, unlocked the secrets of the fragments of DNA. The process was painstaking – first they needed to establish whether there was DNA hidden in the sediment, and if there was, could they successfully detach the DNA from the mineral grains – like clay particles and quartz crystals – to examine it? The answer, eventually, was yes. The researchers compared every single DNA fragment with extensive libraries of DNA collected from present-day animals, plants and microorganisms.

The scientists discovered evidence of animals, plants and microorganisms including reindeer, hares, lemmings, birch and poplar trees. They even found that Mastodon, an Ice Age elephant, roamed as far as Greenland before later becoming extinct. Previously it was thought the range of the species did not extend from its known origins of North and Central America.

Some of the DNA fragments were easy to classify as predecessors to present-day species, others could only be linked at genus level, and some originated from species impossible to place in the DNA libraries of animals, plants and microorganisms still living today.

The findings have opened up a whole new period in DNA detection. Thanks to a new generation of extraction and sequencing equipment, researchers will be able to locate and identify extremely small and damaged fragments of genetic information in sediments considered previously unfit for DNA preservation.

“DNA generally survives best in cold, dry conditions such as those that prevailed during most of the period since the material was deposited at Kap København. Now that we have successfully extracted ancient DNA from clay and quartz, it may be possible that clay may have preserved ancient DNA in warm, humid environments in sites found in Africa,” Professor Willerslev concludes.

The paper “A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA” is published in Nature. Material provided by the by University of Cambridge.

Adblock test (Why?)



Source link

Continue Reading

Science

NASA posts high-resolution images of Orion’s final lunar flyby

Published

 on

Orion just made its final pass around the moon on its way to Earth, and NASA has released some of the spacecraft’s best photos so far. Taken by a high-resolution camera (actually a heavily modified GoPro Hero 4) mounted on the tip of Orion’s solar arrays, they show the spacecraft rounding the Moon then getting a closeup shot of the far side.

The photos Orion snapped on its first near pass to the Moon were rather grainy and blown out, likely because they were captured with Orion’s Optical Navigation Camera rather than the solar array-mounted GoPros. Other GoPro shots were a touch overexposed, but NASA appears to have nailed the settings with its latest series of shots.

Space photos were obviously not the primary goal of the Artemis I mission, but they’re important for public relations, as NASA learned many moons ago. It was a bit surprising that NASA didn’t show some high-resolution closeups of the Moon’s surface when it passed by the first time, but better late than never.

Orion’s performance so far has been “outstanding,” program manager Howard Hu told reporters last week. It launched on November 15th as part of the Artemis 1 mission atop NASA’s mighty Space Launch System. Days ago, the craft completed a three and a half minute engine burn (the longest on the trip so far) to set it on course for a splashdown on December 11th.

Genius Dog 336 x 280 - Animated

The next mission, Artemis II, is scheduled in 2024 to carry astronauts on a similar path to Artemis I without landing on the moon. Then, humans will finally set foot on the lunar surface again with Artemis III, slated for launch in 2025.

Source link

Continue Reading

Trending