Newswise — Scientists seeking to bring to Earth the fusion energy that drives the sun and stars use radio frequency (RF) waves — the same waves that bring radio and television into homes — to heat and drive current in the plasma that fuels fusion reactions. Scientists now have developed a path-setting way to measure the waves that could be used to validate predictions of their impact, setting the stage for enhanced future experiments that could result in bringing energy from fusion to Earth.
The potential breakthrough, led by researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), could lead to follow-up experiments on the National Spherical Tokamak Experiment-Upgrade (NSTX-U), the flagship fusion experiment at PPPL that is undergoing repair, as well as other fusion facilities around the world. “If our method turns out to work it would be a very useful tool for many fusion reactors,” said Grant Rutherford, a first-year graduate student at the Massachusetts Institute of Technology (MIT) and lead author of a paper in the Review of Scientific Instruments that he wrote as a Brown University DOE Science Undergraduate Laboratory Intern (SULI) at PPPL.
Key to predicting the impact of RF waves is measuring the fluctuations, or swings, they create in the density of fusion plasmas. “Once we have those fluctuations we would be able to work backwards to see what those RF fields were that created the fluctuations,” Rutherford said.
However, the high frequency of RF waves causes the swings to occur too rapidly to measure. So the researchers created a “beat wave” by launching two waves at different frequencies, a technique that produced measurable swings. “If we were able to both create a beat wave fluctuation and measure it, we would have a new tool for validating predictions for RF heating and current drive,” Rutherford explained.
Such measurements would have wide-ranging benefits. For example, they could facilitate study of the performance of RF wave actuators, said PPPL physicist Nicola Bertelli, a co-author of the paper, and could enable validation of RF calculation tools developed throughout the fusion community. Moreover, said David Smith, a University of Wisconsin physicist and co-author of the paper, “Our calculations provide an initial assessment of the technique and motivate follow-up experiments on NSTX-U.”
Fusion reactions combine light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei that makes up 99 percent of the visible universe — to generate massive amounts of energy. Reproducing and controlling this process on Earth would create a virtually inexhaustible supply of safe and clean power to generate electricity. Fusion could become a major contributor to the U.S. transition from fossil fuels to a low-carbon source of electrical generation.
Testing the technique
Rutherford and co-authors tested their technique by creating a synthetic version of a 2D beam emission spectroscopy (BES) diagnostic to evaluate simulated RF injections into the plasma. Their aim was to understand and improve the ability to measure the RF field waves that create the swings.
Going forward, “We’re hoping that by increasing our ability to measure, we will increase our ability to understand heating and current drive processes, but we’re leaving that to future work,” Rutherford said. Such work could also show whether the BES diagnostic the scientists based their model on could measure the density swings in actual fusion plasmas, or whether some other diagnostic would do the critical job better.
The DOE Office of Science (FES) supported this work.
PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit energy.gov/science.
NASA discovers double crater on the moon – CTV News
The moon has a new double crater after a rocket body collided with its surface on March 4.
New images shared by NASA’s Lunar Reconnaissance Orbiter, which has been circling the moon since 2009, have revealed the location of the unusual crater.
The impact created two craters that overlap, an eastern crater measuring 59 feet (18 metres) across and a western crater spanning 52.5 feet (16 metres). Together, they create a depression that is roughly 91.8 feet (28 metres) wide in the longest dimension.
Although astronomers expected the impact after discovering that the rocket part was on track to collide with the moon, the double crater it created was a surprise.
Typically, spent rockets have the most mass at the motor end because the rest of the rocket is largely just an empty fuel tank. But the double crater suggests that this object had large masses at both ends when it hit the moon.
The exact origin of the rocket body, a piece of space junk that had been careening around for years, is unclear, so the double crater could help astronomers determine what it was.
The moon lacks a protective atmosphere, so it’s littered with craters created when objects like asteroids regularly slam into the surface.
This was the first time a piece of space junk unintentionally hit the lunar surface that experts know of. But craters have resulted from spacecraft being deliberately crashed into the moon.
For example, four large moon craters attributed to the Apollo 13, 14, 15 and 17 missions are all much larger than each of the overlapping craters created during the March 4 impact. However, the maximum width of the new double crater is similar to the Apollo craters.
Bill Gray, an independent researcher focused on orbital dynamics and the developer of astronomical software, was first to spot the trajectory of the rocket booster.
Gray had initially identified it as the SpaceX Falcon rocket stage that launched the US Deep Space Climate Observatory, or DSCOVR, in 2015 but later said he’d gotten that wrong and it was likely from a 2014 Chinese lunar mission — an assessment NASA agreed with.
However, China’s Ministry of Foreign Affairs denied the booster was from its Chang’e-5 moon mission, saying that the rocket in question burned up on reentry to Earth’s atmosphere.
No agencies systematically track space debris so far away from Earth, and the confusion over the origin of the rocket stage has underscored the need for official agencies to monitor deep-space junk more closely, rather than relying on the limited resources of private individuals and academics.
However, experts say that the bigger challenge is the space debris in low-Earth orbit, an area where it can collide with functioning satellites, create more junk and threaten human life on crewed spacecraft.
There are at least 26,000 pieces of space junk orbiting Earth that are the size of a softball or larger and could destroy a satellite on impact; over 500,000 objects the size of a marble — big enough to cause damage to spacecraft or satellites; and over 100 million pieces the size of a grain of salt, tiny debris that could nonetheless puncture a spacesuit, according to a NASA report issued last year.
7 Amazing Dark Sky National Parks – AARP
Can’t afford to join a commercial space mission offered by Jeff Bezos or Richard Branson? Consider the next best thing: seeing a starry, starry night in a sea of darkness, unimpeded by artificial light, at one of the International Dark Sky Parks in the U.S. It’s a rare treat, since light pollution prevents nearly 80 percent of Americans from seeing the Milky Way from their homes.
The International Dark-Sky Association (IDSA) has certified 14 of the nation’s 63 national parks as dark sky destinations. So visitors can take full advantage of such visibility, many of them offer specialized after-dark programs, from astronomy festivals and ranger-led full-moon walks to star parties and astrophotography workshops. If you prefer to stargaze on your own at a park, the National Park Service recommends bringing a pair of 7-by-50 binoculars, a red flashlight, which enhances night vision, and a star chart, which shows the arrangement of stars in the sky.
Here are seven of the IDSA-certified parks where you can appreciate how the heavens looked from the Earth before the dawn of electric light.
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Award-winning travel writer Veronica Stoddart is the former travel editor of USA Today. She has written for dozens of travel publications and websites.
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A Mystery Rocket Left A Crater On The Moon – Forbes
While we think of the moon as a static place, sometimes an event happens that reminds us that things can change quickly.
On March 4, a human-made object (a rocket stage) slammed into the moon and left behind a double crater, as seen by NASA’s Lunar Reconnaissance Orbiter (LRO) mission.
Officials announced June 23 that they spotted a double crater associated with the event. But what’s really interesting is there’s no consensus about what kind of rocket caused it.
China has denied claims that the rocket was part of a Long March 3 rocket that launched the country’s Chang’e-5 T1 mission in October 2014, although the orbit appeared to match. Previous speculation suggested it might be from a SpaceX rocket launching the DISCOVR mission, but newer analysis has mostly discredited that.
On a broader scale, the value of LRO observations like this is showing how the moon can change even over a small span of time. The spacecraft has been in orbit there since 2009 and has spotted numerous new craters since its arrival.
It’s also a great spacecraft scout, having hunted down the Apollo landing sites from orbit and also having tracked down a few craters from other missions that slammed into the moon since the dawn of space exploration.
It may be that humans return to the moon for a closer-up look in the coming decade, as NASA is developing an Artemis program to send people to the surface no earlier than 2025.
LRO will also be a valuable scout for that set of missions, as the spacecraft’s maps will be used to develop plans for lunar bases or to help scout safe landing sites for astronauts.
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