All's not as it appears, this tale has many twists -
but if I wasn't here documenting the story
would that mean that the plot did not exist?

— Peter Hammill

Astronomy

Hybrid design could make nuclear fusion reactors more efficient

Two types of fusion reactor called tokamaks and stellarators both have drawbacks – but a new design combining parts from both could offer the best of both worlds
Categories: Astronomy

Did rock art spread from one place or was it invented many times?

Rock art is a truly global phenomenon, with discoveries of cave paintings and etchings on every continent that ancient humans inhabited – but how many times was it invented over human history?
Categories: Astronomy

Soviet-era cosmonaut Vyacheslav Zudov, who survived only Soyuz splashdown, dies

Space.com - 7 hours 22 min ago
Soviet-era cosmonaut Vyacheslav Zudov, whose failed Soyuz 23 docking with Russia's Salyut 5 space station ended with the first and only emergency splashdown on board a Soyuz spacecraft, has died.
Categories: Astronomy

Boeing's 1st Starliner astronaut mission return delayed to June 22

Space.com - 7 hours 55 min ago
The return of Boeings 1st crewed Starliner mission has been delayed to June 22.
Categories: Astronomy

Warp Drives Could Generate Gravitational Waves

Universe Today - 8 hours 13 min ago

Will future humans use warp drives to explore the cosmos? We’re in no position to eliminate the possibility. But if our distant descendants ever do, it won’t involve dilithium crystals, and Scottish accents will have evaporated into history by then.

Warp drives have their roots in one of the most popular science fiction franchises ever, but they do have a scientific basis. A new paper examines the science behind them and asks if a warp drive containment failure would emit detectable gravitational waves.

The paper is titled “What no one has seen before: gravitational waveforms from warp drive collapse.” The authors are Katy Clough, Tim Dietrich, and Sebastian Khan, physicists from institutions in the UK and Germany.

There’s room for warp drives in General Relativity, and Mexican physicist Miguel Alcubierre described how they could theoretically work in 1994. He’s well-known in space and physics circles for his Alcubierre Drive.

Everyone knows that no object can travel faster than the speed of light. But warp drives may offer a workaround. By warping spacetime itself, a spacecraft with a warp drive wouldn’t be breaking the faster-than-light (FTL) rule.

“Despite originating in science fiction, warp drives have a concrete description in general relativity, with Alcubierre first proposing a spacetime metric that supported faster-than-light travel,” the authors write.

There are clear scientific barriers to actually making a warp drive. But it’s possible to simulate how one would work and how they may be detectable via gravitational waves in the event of a failure. Warp drives distort spacetime itself, just like binary mergers of compact objects like black holes and neutron stars. It’s theoretically possible that they emit a gravitational wave signal in the same vein as mergers. “To search for such signals and to correctly identify them in the measured data, it is important to understand their phenomenology and properties,” the authors explain.

It begins with understanding how warp drives might work, and for that, we have to delve deeply into physics.

“The principle idea behind a warp drive is that instead of exceeding the speed of light directly in a local reference frame, which would violate Lorentz invariance, a “warp bubble” could traverse distances faster than the speed of light (as measured by some distant observer) by contracting spacetime in front of it and expanding spacetime behind it,” the paper states.

The first barrier is that warp drives require a Null Energy Condition (NEC). Physics states that a region of space cannot have a negative energy density. There are theoretical workarounds for that, but for now, none of them are practical.

“Other issues with the warp drive metric include the potential for closed time-like curves and, from a more practical perspective, the difficulties for those in the ship in controlling and deactivating the bubble,” the authors explain. This is because there would be no way for the crew to send signals to the front of the ship. It’s difficult for events inside the bubble to influence events outside the warp bubble, as this paper explains.

“From the perspective of simulating the warp drive dynamically, the key challenge is stability,” the authors explain. Equations show that the Alcubierre Drive can initiate a warp bubble using the Einstein Equation, but no known equations can sustain it. “There is (to our knowledge) no known equation of state that would maintain the warp drive metric in a stable configuration over time. Therefore, whilst one can require that initially, the warp bubble is constant, it will quickly evolve away from that state, and, in most cases, the warp fluid and spacetime deformations will disperse or collapse into a central point.”

Though instability is a prime obstacle to warp drives, it’s also what could make them detectable. If an Alcubierre Drive achieves a constant velocity, it’s not detectable. It generates no gravitational waves and has no ADM mass. ADM stands for Arnowitt–Deser—Misner, named for three physicists. I’ll leave it to curious readers to read more about ADM mass.

But the warp drive is only undetectable if it’s constant and stable. Once it breaks down, accelerates or decelerates, it could be detectable. In their work, the authors allow the warp drive bubble to collapse. “Physically, this could be related to a breakdown in the containment field that the post-warp civilization (presumably) uses to support the warp bubble against collapse,” they write.

In their formulations, the nature of the ship itself isn’t important. Only the warp bubble and the warp fluid inside are significant.

The researchers simulated the breakdown of the warp bubble. They found that the collapse generated gravitational waves with characteristics different from those generated by mergers. “The signal comes as a burst, initially having no gravitational wave content, followed by an oscillatory period with a characteristic frequency of order 1/[R],” they write. “Overall, the signal is very distinct from the typical compact binary coalescences observed by gravitational wave detectors and more similar to events like the collapse of an unstable neutron star or the head-on collision of two black holes.”

The authors point out that though the warp drive creates a GW signal, it’s outside the frequency range of our current ground-based detectors. “Proposals for higher frequency detectors have been made, so in the future, one may be able to put bounds on the existence of such signals,” they write.

The ship itself could also send some type of multimessenger signal, but it’s difficult to know how the ship’s matter would interact with regular matter. “Since we do not know the type of matter used to construct the warp ship, we do not know whether it would interact (apart from gravitationally) with normal matter as it propagates through the Universe,” the researchers explain.

This is a fun thought experiment. It’s possible that some type of workaround to FTL travel will exist one day in the distant future. If it does, it may be related to a better understanding of dark matter and dark energy. If any ETIs exist, they may be in a position to exploit fundamental knowledge of the Universe that we don’t yet possess.

If they’ve figured out how to construct and use a warp drive, even with all of its seeming impossibilities, their activities might create gravitational waves that our future observatories could detect, even in other galaxies. But for now, it’s all theoretical.

“We caution that the waveforms obtained are likely to be highly specific to the model employed, which has several known theoretical problems, as discussed in the Introduction,” the authors write in their conclusion. “Further work would be required to understand how generic the signatures are and properly characterize their detectability.”

Without a doubt, some curious physicists will continue to work on this.

The post Warp Drives Could Generate Gravitational Waves appeared first on Universe Today.

Categories: Astronomy

How China's Chang'e 6 minirover snapped its epic photo on the moon's far side

Space.com - 8 hours 21 min ago
China has revealed details about a miniature rover tucked away on the country's pioneering Chang'e 6 lunar far side sample-return mission.
Categories: Astronomy

Boeing's Starliner astronaut taxi spotted at ISS (satellite photo)

Space.com - 9 hours 21 min ago
Maxar's WorldView-3 satellite captured a striking image of Boeing's Starliner capsule docked to the ISS on June 7, a day after the vehicle arrived at the orbiting complex.
Categories: Astronomy

UK election: How can the next government get climate goals on track?

The UK’s journey to net zero has stalled – whoever wins the 4 July election will need to get it moving again, but many climate scientists are frustrated with what the main parties are offering
Categories: Astronomy

UK election: How can next government get climate goals back on track?

The UK’s journey to net zero has stalled – whoever wins the 4 July election will need to get it moving again, but many climate scientists are frustrated with what the main parties are offering
Categories: Astronomy

UK election: How can next government get climate goals back on track?

New Scientist Space - Cosmology - 9 hours 22 min ago
The UK’s journey to net zero has stalled – whoever wins the 4 July election will need to get it moving again, but many climate scientists are frustrated with what the main parties are offering
Categories: Astronomy

China's Chang'e 6 spacecraft finds long-sought particles on far side of the moon

Space.com - 9 hours 33 min ago
A European experiment aboard China's Chang'e 6 mission has recorded certain charged particles previously undetected on the moon's surface.
Categories: Astronomy

JWST spotted an incredible number of supernovae in the early universe

Using the James Webb Space Telescope, astronomers have increased the number of known supernovae in the early universe by a factor of 10 and found the most distant one ever confirmed
Categories: Astronomy

JWST spotted an incredible number of supernovae in the early universe

New Scientist Space - Cosmology - 11 hours 22 min ago
Using the James Webb Space Telescope, astronomers have increased the number of known supernovae in the early universe by a factor of 10 and found the most distant one ever confirmed
Categories: Astronomy

The sun's magnetic field is about to flip. Here's what to expect.

Space.com - 12 hours 22 min ago
As we approach solar maximum, something strange is happening to the sun's magnetic field. We explore this flip in polarity in more detail and look at the effects it could have on Earth.
Categories: Astronomy

An Astronaut Might Need Kidney Dialysis on the Way Home from Mars

Universe Today - 12 hours 40 min ago

Long term space exploration comes with many challenges. Not least is how much toilet paper to take but more worryingly is the impact on human physiology. We have not evolved in a weightless environment, we are not used to floating around for months on end nor are we able to cope with increased levels of radiation. It is likely that organs like the kidneys will become damaged but it make take time for signs to appear. Researchers are developing ways to detect organ issues in the early stages and develop ways to protect them during long duration flights. 

We have known for some years that space flight causes health problems. Reduced muscle and bone density are the more well known but since the 1970’s we have also seen a weakening of the heart, eyesight issues and kidney stone development. The main cause of the problem is thought to be increased exposure to radiation from space. It’s not just the radiation from the Sun but Galactic Cosmic Radiation from deep space also plays a part. Fortunately for us here on Earth, the magnetic field protects us and those in low Earth orbit to a degree too. Those who travel further afield; to the Moon and other planets will be far more at risk. 

ESA astronaut Alexander Gerst gets a workout on the Advanced Resistive Exercise Device (ARED). Credit: NASA

To date, no-one has attempted to study what might be happening inside our organs as a result of long duration space flight, until now. A new study, published in Nature Communications, reports upon the analysis of kidney health in space flight. The study was funded by Wellcome, St Peters Trust and Kidney Research UK and was undertaken by a team of researchers from over 40 groups. 

The research team collected samples from over 40 low Earth orbit missions from humans and mice chiefly from the International Space Station. Using these samples they conducted biomolecular, physiological and anatomical assessments. Using mice, they were able to simulate Galactic Cosmic Radiation doses equivalent to a 1.5 year to 2.5 year Mars mission. 

NASA Image: ISS020E049908 – NASA astronaut Nicole Stott, Expedition 20/21 flight engineer, is pictured near the Mice Drawer System (MDS) in the Kibo laboratory of the International Space Station.

Indications from the study showed that the kidney from both animal and human experienced changes. Parts of the kidney, known as tubules, are responsible for tweaking the calcium and salt balances and these showed signs of shrinkage after less than a month in space. The researchers believe though that this is more likely the result of weightlessness rather than radiation doses. The team did suggest however that further research is appropriate to see if the combination of increased doses of radiation coupled with microgravity had an increasing effect. 

Another finding of the study was the way in which salt is processed by the kidneys. It is now thought that fundamental changes to how this is handled leads to the formation of kidney stones whilst it was originally assumed to be the result solely of microgravity. 

Perhaps the most shocking finding of the study though was that anyone venturing beyond the confines fo the Earth’s protective magnetic field for 2.5 years is likely to experience permanent kidney damage and loss of function. This was demonstrated in the mice samples that had experienced a simulated Galactic Cosmic Radiation dose for that period fo time. The impact of this is quite staggering. Currently any astronaut venturing to Mars is likely to need kidney dialysis on the way back! The race is now on to find new ways to protect astronauts, and organs during long duration spaceflights. 

Source : Would astronauts’ kidneys survive a roundtrip to Mars?

The post An Astronaut Might Need Kidney Dialysis on the Way Home from Mars appeared first on Universe Today.

Categories: Astronomy

The Unistellar eVscope 2 is $1160 off ahead of Prime Day

Space.com - 12 hours 57 min ago
Get Amazon's lowest price on a smart telescope, which we rate very highly, save over $1160 and beat the crowds in this pre-Pime Day deal.
Categories: Astronomy

This Week's Sky at a Glance, June 14 – 23

Sky & Telescope Magazine - 13 hours 41 min ago

On solstice week the brightening Moon moves across the evening sky from Spica to Scorpius. On Monday, it helps you find a piece of Centaurus from as far north as southernmost Canada!

The post This Week's Sky at a Glance, June 14 – 23 appeared first on Sky & Telescope.

Categories: Astronomy

Moon Lander Detects Technosignatures Coming from Earth

Universe Today - 13 hours 50 min ago

The search for life has to be one of the most talked about questions in science. The question is, what do you look for? The Odysseus lunar lander has recently detected signs of a technologically advanced civilisation…on Earth! The lander is equipped with an instrument called ROLSES which has probed the radio emissions from Earth as if it was an exoplanet to se if it could detect signs of life! 

Odysseus was launched on 15 February, it was the Intuitive Machines lunar lander and it touched down in the solar polar region of the Moon seven days later. Since then it has been collecting valuable data from the area as a prelude for future human exploration. It was part of the Commercial Lunar Payload Services program which have all been built by private companies. Despite the hiccup of a landing where Odysseus tipped onto its side it has still been performing well.

There have been other challenges along the way. The laser guided navigation system which was supposed to aid the landing over the rocky surface failed. In a nod to Armstrong landing Apollo 11 manually in the last few minutes, the ground crew had to land using the optical camera system alone.  Even the journey to the Moon was not without incident. One of the antennae of the ROLSES system overheated and became dislodged from its housing.  On landing, an image showed the antenna sticking out. 

Neil Armstrong and Buzz Aldrin plant the US flag on the Lunar Surface during 1st human moonwalk in history 45 years ago on July 20, 1969 during Apollo 1l mission. Credit: NASA

On board Odysseus is the Radio wave Observations at the Lunar Surface of the photo Electron Sheath or ROLSES for short. It is a radio experiment designed to explore properties of the Earth’s atmosphere from the surface of the Moon. It was a unique opportunity to observe Earth in a completely different way and, to see if our approach for hunting for technologically capable alien civilisations are correct. 

The instrument was built at NASA’s Goddard Space Flight Center in Maryland and included radio antennae and a device called a radio spectrometer. It’s purpose was to record a wide range of radio emissions from the ‘radio quiet’ locale of the Moon. It turned out to be a bit of a bonus though as the team were able to record radio waves coming from Earth for about an hour and a half. 

NASA has selected three commercial Moon landing service providers that will deliver science and technology payloads under Commercial Lunar Payload Services (CLPS) as part of the Artemis program. Each commercial lander will carry NASA-provided payloads that will conduct science investigations and demonstrate advanced technologies on the lunar surface, paving the way for NASA astronauts to land on the lunar surface by 2024…The selections are:..• Astrobotic of Pittsburgh has been awarded $79.5 million and has proposed to fly as many as 14 payloads to Lacus Mortis, a large crater on the near side of the Moon, by July 2021…• Intuitive Machines of Houston has been awarded $77 million. The company has proposed to fly as many as five payloads to Oceanus Procellarum, a scientifically intriguing dark spot on the Moon, by July 2021…• Orbit Beyond of Edison, New Jersey, has been awarded $97 million and has proposed to fly as many as four payloads to Mare Imbrium, a lava plain in one of the Moon’s craters, by September 2020. ..All three of the lander models were on display for the announcement of the companies selected to provide the first lunar landers for the Artemis program, on Friday, May 31, 2019, at NASA’s Goddard Space Flight Center in Greenbelt, Md. ..Read more: https://go.nasa.gov/2Ki2mJo..Credit: NASA/Goddard/Rebecca Roth

We have known for some time that all the signals from mobile phones and TV/radio  broadcast have been slowly drifting out into space (and have now reached a distance of just over 100 light years.) All of these emissions are potentially detectable but the further away from Earth, the weaker the signal. Within those signals, the team were able to detect signs of an intelligent, technological civilisation. The attention now will of course turn to hunting down the same signals from exoplanets, but perhaps not from ROLSES, something a little larger may be required. 

Source : In new experiment, scientists record Earth’s radio waves from the Moon

The post Moon Lander Detects Technosignatures Coming from Earth appeared first on Universe Today.

Categories: Astronomy

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APOD - Thu, 06/13/2024 - 8:00pm

It was the first time ever.


Categories: Astronomy, NASA

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APOD - Thu, 06/13/2024 - 8:00pm

Why is the sky near


Categories: Astronomy, NASA