Tag Archives: interstellar

China builds the world’s first artificial moon

Chinese scientists have built an ‘artificial moon’ possessing lunar-like gravity to help them prepare astronauts for future exploration missions. The structure uses a powerful magnetic field to produce the celestial landscape — an approach inspired by experiments once used to levitate a frog.

The key component is a vacuum chamber that houses an artificial moon measuring 60cm (about 2 feet) in diameter. Image credits: Li Ruilin, China University of Mining and Technology

Preparing to colonize the moon

Simulating low gravity on Earth is a complex process. Current techniques require either flying a plane that enters a free fall and then climbs back up again or jumping off a drop tower — but these both last mere minutes. With the new invention, the magnetic field can be switched on or off as needed, producing no gravity, lunar gravity, or earth-level gravity instantly. It is also strong enough to magnetize and levitate other objects against the gravitational force for as long as needed.

All of this means that scientists will be able to test equipment in the extreme simulated environment to prevent costly mistakes. This is beneficial as problems can arise in missions due to the lack of atmosphere on the moon, meaning the temperature changes quickly and dramatically. And in low gravity, rocks and dust may behave in a completely different way than on Earth – as they are more loosely bound to each other.

Engineers from the China University of Mining and Technology built the facility (which they plan to launch in the coming months) in the eastern city of Xuzhou, in Jiangsu province. A vacuum chamber, containing no air, houses a mini “moon” measuring 60cm (about 2 feet) in diameter at its heart. The artificial landscape consists of rocks and dust as light as those found on the lunar surface-where gravity is about one-sixth as powerful as that on Earth–due to powerful magnets that levitate the room above the ground. They plan to test a host of technologies whose primary purpose is to perform tasks and build structures on the surface of the Earth’s only natural satellite.

Group leader Li Ruilin from the China University of Mining and Technology says it’s the “first of its kind in the world” that will take lunar simulation to a whole new level. Adding that their artificial moon makes gravity “disappear.” For “as long as you want,” he adds.

In an interview with the South China Morning Post, the team explains that some experiments take just a few seconds, such as an impact test. Meanwhile, others like creep testing (where the amount a material deforms under stress is measured) can take several days.

Li said astronauts could also use it to determine whether 3D printing structures on the surface is possible rather than deploying heavy equipment they can’t use on the mission. He continues:

“Some experiments conducted in the simulated environment can also give us some important clues, such as where to look for water trapped under the surface.”

It could also help assess whether a permanent human settlement could be built there, including issues like how well the surface traps heat.

From amphibians to artificial celestial bodies

The group explains that the idea originates from Russian-born UK-based physicist Andre Geim’s experiments which saw him levitate a frog with a magnet – that gained him a satirical Ig Nobel Prize in 2000, which celebrates science that “first makes people laugh, and then think.” Geim also won a Nobel Prize in Physics in 2010 for his work on graphene.

The foundation of his work involves a phenomenon known as diamagnetic levitation, where scientists apply an external magnetic force to any material. In turn, this field induces a weak repulsion between the object and the magnets, causing it to drift away from them and ‘float’ in midair.

For this to happen, the magnetic force must be strong enough to ‘magnetize’ the atoms that make up a material. Essentially, the atoms inside the object (or frog) acts as tiny magnets, subject to the magnetic force existing around them. If the magnet is powerful enough, it will change the direction of the electrons revolving around the atom’s nuclei, allowing them to produce a magnetic field to repulse the magnets.

Diamagnetic levitation of a tiny horse. Image credits: Pieter Kuiper / Wiki Commons.

Different substances on Earth have varying degrees of diamagnetism which affect their ability to levitate under a magnetic field; adding a vacuum, as was done here, allowed the researchers to produce an isolated chamber that mimics a microgravity environment.

However, simulating the harsh lunar environment was no easy task as the magnetic force needed is so strong it could tear apart components such as superconducting wires. It also affected the many metallic parts necessary for the vacuum chamber, which do not function properly near a powerful magnet.

To counteract this, the team came up with several technical innovations, including simulating lunar dust that could float a lot easier in the magnetic field and replacing steel with aluminum in many of the critical components.

The new space race

This breakthrough signals China’s intent to take first place in the international space race. That includes its lunar exploration program (named after the mythical moon goddess Chang’e), whose recent missions include landing a rover on the dark side of the moon in 2019 and 2020 that saw rock samples brought back to Earth for the first time in over 40 years.

Next, China wants to establish a joint lunar research base with Russia, which could start as soon as 2027.  

The new simulator will help China better prepare for its future space missions. For instance, the Chang’e 5 mission returned with far fewer rock samples than planned in December 2020, as the drill hit unexpected resistance. Previous missions led by Russia and the US have also had related issues.

Experiments conducted on a smaller prototype simulator suggested drill resistance on the moon could be much higher than predicted by purely computational models, according to a study by the Xuzhou team published in the Journal of China University of Mining and Technology. The authors hope this paper will enable space engineers across the globe (and in the future, the moon) to alter their equipment before launching multi-billion dollar missions.

The team is adamant that the facility will be open to researchers worldwide, and that includes Geim. “We definitely welcome Professor Geim to come and share more great ideas with us,” Li said.

Hubble spots our second interstellar visitor — a comet

NASA’s Hubble Space Telescope has just taken a peek at the second interstellar object to visit the solar system — a comet.

Image credits NASA / ESA / J. DePasquale (STScI).

Based on its current speed and trajectory, 2I/Borisov likely came from outside our solar system. It is the second such object after the asteroid ‘Oumuamua (identified in 2017). However, the two are very different beasts — while ‘Oumuamua was a rocky, solid body, 2I/Borisov is a comet. The image taken by Hubble is the best look we’ve had at 2I/Borisov so far and reveals a body of dust around a central core (which is too small to be seen in the image).

It cometh second

Whereas ‘Oumuamua appeared to be a rock, Borisov is really active, more like a normal comet. It’s a puzzle why these two are so different,” said David Jewitt of the University of California, Los Angeles (UCLA), leader of the Hubble team who observed the comet.

Being the second interstellar object we’ve found so close to home, researchers are very keen to study the properties and nature of 2I/Borisov. Its chemical composition, structure, and the dust around it are products of its host star system and can teach us about how they form. We won’t know for sure without further observation, but so far, the comet’s properties appear to be very similar to those in the Solar System.

The comet was 260 million miles from Earth when Hubble took its picture. It is on a hyperbolic path around the Sun, currently moving at around 110,000 miles per hour. Its closest approach will be on Dec. 7, 2019, when it will be twice as far from the Sun as Earth. By mid-2020, NASA adds, it will make its way past Jupiter and onto interstellar space.

“It’s traveling so fast it almost doesn’t care that the Sun is there,” said Jewitt.

2I/Borisov was first discovered by Crimea-based amateur astronomer Gennady Borisov on Aug. 30, 2019. After a week of observations, the International Astronomical Union’s Minor Planet Center and the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory in Pasadena, California, confirmed that it came from interstellar space. Future Hubble observations of 2I/Borisov are planned through January 2020, with more being proposed.

The martian

Hollywood’s Portrayal of Space: Part 2

This is a guest post by Dave Syndergaard, Assistant Professor of Space Studies, American Public University. The following article is Part 2 of a two-part series. Read Part 1

When Hollywood makes a movie set in space, the science in the movie may or may not be based in reality. Part 1 of this series discussed the space science “Armageddon” and “Gravity.” This article critiques Hollywood’s depiction of space in “The Martian” and “Interstellar,” as well as space sound and movement.

The Martian

The martian

Credit: Fox Movies

“The Martian” is one of my favorite space movies It’s pretty accurate, but not flawless.

[Spoiler Alert: If you haven’t seen the movie yet (shame on you), then you might want to skip this part.]

First, the movie shows a giant windstorm on Mars that causes the return ship to rock violently on its supports. The atmosphere of Mars is about 1% as dense as Earth’s atmosphere.

A huge windstorm on Mars would feel like a gentle summer breeze to us. It certainly wouldn’t cause a large, heavy rocket to move.

Second, Mars doesn’t have a protective magnetosphere because there’s no planetary magnetic field. As a result, high-energy galactic cosmic rays (GCRs) and charged particles from the sun hammer the surface of Mars.

The movie makes no mention of how the astronauts were protected from radiation. Damon’s character would have been fried or at least gotten cancer long before his rescuers arrived.

Third, the “Iron Man” rocket thing Watney does with his spacesuit by ripping a hole in his glove and using it like a rocket was hilarious. I teach rocket propulsion and orbital mechanics. That part of the movie made me roll my eyes so hard I gave myself a small headache.

[ALSO READ] NASA wants to grow potatoes on the red planet. Just like Mark Watnet from ‘The Martian’

Other problems, like the fact that hydrazine is too toxic for any human exposure, were easy to overlook. Overall, the movie was awesome.

Interstellar

Interstellar

Credit: Legendary Pictures

“Interstellar” was another recent movie that was fun to watch and not too bad, as far as science goes.

The movie uses a wormhole as a space transportation system. Traveling though wormholes (the technical term is “Einstein-Rosen Bridge”) has been a plot device in science fiction movies and stories for decades. But there are several problems with the concept as a transportation mechanism.

The first problem is size. Primordial wormholes are predicted to exist on microscopic levels, about 10–33 centimeters. It’s possible that as the universe has expanded, some wormholes may have stretched to larger sizes. Another problem is stability. Einstein-Rosen wormholes would collapse quickly.

[ALSO SEE] Interstellar movie is helping scientists model REAL black holes

Recent research suggests a wormhole containing “exotic” matter (not be confused with dark matter or antimatter) could stay open and stable for longer periods of time. I wouldn’t take the chance on these wormholes staying around long enough to travel through, however.

Other Movie Mistakes Involve “Real” Sound in Space and Spacecraft Movement

That “sound in space” thing in movies and TV shows has bothered me since I was a teenager and learned that sound waves can’t propagate through space.

Most science fiction writers and screenwriters take “poetic license” with space sound to make a scene more exciting. For sound to travel, it needs something with molecules for the sound to travel through.

On Earth, sound travels to your ears by vibrating air molecules. In the large empty areas between stars and planets, there are no molecules to vibrate and no sound.
There’s also the issue of how spacecraft move around in space. The notion of spacecraft “yanking and banking” in space is nonsense.

Moving around in Earth’s atmosphere is very different than maneuvering in space.In space, there isn’t any air for wings and rudders to push against. Spacecraft movement is governed by gravitational pull and by pushing propellant through directional nozzles.

Here’s my advice: Go enjoy all of these movies, as well as future space movies. But employ your critical thinking skills.
About the Author: Dave Syndergaard is a professor of Space Studies at American Public University. His degrees are in electrical and systems engineering. Dave is a retired Air Force officer with experience in satellite operations, laser weapon studies, satellite communications and nuclear weapons effects testing. For nine years, he taught space science at the National Security Space Institute in Colorado Springs.

gargantua black hole

Interstellar movie is helping scientists model REAL black holes

The team behind Interstellar’s awesome special effects meant business when they set out to emulate space, celestial objects, and black holes facts as scientifically accurate as possible. In a paper published in the journal Classical and Quantum Gravity, the special effects crew describe at length the innovative computer code they used to generate stunning imagery, but also make new scientific discoveries. Whenever a SciFi movie spews new scientific advancement, well, you know it’s a good one!

Rendering the science of black holes

gargantua black hole

The Gargantua black hole from Interstellar. Credit: Double Negative

Interstellar’s special effects were handled by the London-based visual effects company Double Negative. The people in charge there, per director Christopher Nolan’s request, wanted to work as realistically as possible, so they enlisted world-renowned theoretical physicist Kip Thorne, a former professor at Caltech, to guide them towards the most accurate simulation ever of what a black hole would look like. So,  Thorne started generating equations that would guide their effects software the way physics governs the real world. They all agreed to first start with wormholes. Hundreds of pages and memos were sent back and forth, and in the end, all the effort paid off. They had made a stunning crystal ball that reflects back the Universe unto itself.

“Science fiction always wants to dress things up, like it’s never happy with the ordinary universe,” Thorne says. “What we were getting out of the software was compelling straight off.”

Thorne’s diagram of how a black hole distorts light. Credit: Kip Thorne

Thorne’s diagram of how a black hole distorts light. Credit: Kip Thorne

Black Holes were a lot more difficult. Light rays that pass close to the black hole get caught and cannot escape. Therefore, the region around the black hole is a dark disk. Light rays that pass a little further away don’t get caught but do get bent by the black hole’s gravity. This makes the starfield appear distorted, as in a funhouse mirror. It also produces multiple images. You would see two duplicate images of the same star on opposite sides of the black hole, because light rays passing the black hole on either side get bent toward you. In fact, there are infinitely many images of each star, corresponding to light rays that circle the black hole several times before coming toward you.

According to Wired:

Filmmakers often use a technique called ray tracing to render light and reflections in images. “But ray-tracing software makes the generally reasonable assumption that light is traveling along straight paths,” says Eugénie von Tunzelmann, a CG supervisor at Double Negative. This was a whole other kind of physics. “We had to write a completely new renderer,” she says.

Some individual frames took up to 100 hours to render, the computation overtaxed by the bendy bits of distortion caused by an Einsteinian effect called gravitational lensing. In the end the movie brushed up against 800 terabytes of data

Einstein’s theory of general relativity predicts that every object bends light rays through its gravity. This is called gravitational lensing. For our Sun this effect is very weak, but it has been measured. For more massive and distant objects in the Universe much stronger lensing has been seen. However, it has not yet been possible to observe this effect near a black hole or to directly photograph the dark disk surrounding a black hole.

Gargantua

O'Neill cylinder rendering, one of my favorite shots from the movie. It's inspired by the ship in Arthur C. Clarke's Rendezvous with Rama, a book I highly recommend.

O’Neill cylinder rendering, one of my favorite shots from the movie. It’s inspired by the ship in Arthur C. Clarke’s Rendezvous with Rama, a book I highly recommend.

For their movie, the Double Negative team took an alternate path from conventional special effects for space movies. Instead of tracing individual light ray paths, they simulated bundles of light which proved to be great for mimicking gravitational lensing. In fact, their code is so accurate that astrophysicists are thinking of using it to model their cosmic oddities.

Eventually, Double Negative hit the jackpot and rendered one what’s already one of the most iconic images in science fiction, rivaling Space Odyssey’s Monolith: the Gargantua black hole. The computer code generated the black hole, completed with its glowing accretion disk with unparalleled clarity.

Co-author of the study and chief scientist at Double Negative, Oliver James, said: “To get rid of the flickering and produce realistically smooth pictures for the movie, we changed our code in a manner that has never been done before. Instead of tracing the paths of individual light rays using Einstein’s equations—one per pixel—we traced the distorted paths and shapes of light beams.”

Co-author of the study Kip Thorne said: “This new approach to making images will be of great value to astrophysicists like me. We, too, need smooth images.”

Oliver James continued: “Once our code, called DNGR for Double Negative Gravitational Renderer, was mature and creating the images you see in the movie Interstellar, we realised we had a tool that could easily be adapted for scientific research.”

Here’s an interesting tidbit from the paper. It seems like Gargantua, although stunning and quite accurate, isn’t actually the most faithful rendition of a black hole they could make. The final version of Gargantua features additional code that takes into account the vast rotational forces that would be created as the black hole spins. Gargantua now looks considerably different, with more matter spewed across one side, while an observer would see different color because of the Doppler effect.

A more accurate version of Gargantua, published in a science paper recently. Credit: IOP

A more accurate version of Gargantua, published in a science paper recently. Credit: IOP