But looks can be deceiving.
In reality, you've unknowingly jumped into an invisible mosh pit of electromagnetic mayhem — the place in space where a supersonic "wind" of charged particles from the Sun crashes head-on into the protective magnetic bubble that surrounds our planet. Traveling at a million miles per hour, the solar wind's protons and electrons sense Earth's magnetosphere too late to flow smoothly around it. Instead, they're shocked, heated, and slowed almost to a stop as they pile up along its outer boundary, the magnetopause, before getting diverted sideways.
Space physicists have had a general sense of these dynamic goings-on for decades. But it wasn't until the advent of the Interstellar Boundary Explorer or IBEX, a NASA spacecraft launched in October 2008, that they've been able to see what the human eye cannot: the first-ever images of this electromagnetic crash scene. They can now witness how some of the solar wind's charged particles are being neutralized by gas escaping from Earth's atmosphere.
A New Way to See Atoms
IBEX wasn't designed to keep tabs on Earth's magnetosphere. Instead, its job is to map interactions occurring far beyond the planets, 8 to 10 billion miles away, where the Sun's own magnetic bubble, the heliosphere, meets interstellar space.
Only two spacecraft, Voyagers 1 and 2, have ventured far enough to probe this region directly. IBEX, which travels in a looping, 8-day-long orbit around Earth, stays much closer to home, but it carries a pair of detectors that can observe the interaction region from afar.
Here's how: When fast-moving protons in the solar wind reach the edge of the heliosphere, they sometimes grab electrons from the slower-moving interstellar atoms around them, like batons getting passed between relay runners. This charge exchange creates electrically neutral hydrogen atoms that are no longer controlled by magnetic fields. Suddenly, they're free to go wherever they want — and because they're still moving fast, they quickly zip away from the interstellar boundary in all directions.
Some of these "energetic neutral atoms," or ENAs, zip past Earth, where they're recorded by IBEX. Its two detectors don't take pictures with conventional optics. Instead, they record the number and energy of atoms arriving from small spots of sky about 7 degrees across (the apparent size of a tennis ball held at arm's length). Because its spin axis always points at the Sun, the spacecraft slowly turns throughout Earth's orbit and its detectors scan overlapping strips that create a complete 360 degrees map every six months.
A Collision Zone Near Earth
Because IBEX is orbiting Earth, it also has a front-row seat for observing the chaotic pileup of solar-wind particles occurring along the "nose" of Earth's magnetopause, about 35,000 miles out. ENAs are created there too, as solar-wind protons wrest electrons from hydrogen atoms in the outermost vestiges of our atmosphere, the exosphere.
Other spacecraft have attempted to measure the density of the dayside exosphere, without much success. NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft probably detected ENAs from this region a decade ago, but its detectors didn't have the sensitivity to pinpoint or measure the source.
Now, thanks to IBEX, we know just how tenuous the outer exosphere really is. "Where the interaction is strongest, there are only about eight hydrogen atoms per cubic centimeter," explains Stephen A. Fuselier, the Lockheed Martin Space Systems researcher who led the mapping effort. His team's results appear in the July 8 issue of Geophysical Research Letters.
The key observations were made in March and April 2009, when IBEX was located far from Earth — about halfway to the Moon's orbit — and its detectors could scan the region directly in front of the magnetopause. During some of the March observations, the European Space Agency's Cluster 3 spacecraft was positioned just in front of the magnetopause, where it measured the number of deflected solar-wind protons directly. "Cluster played a very important role in this study," Fuselier explains. "It was in the right place at the right time."
The new IBEX maps show that the ENAs thin out at locations away from the point of peak intensity. This falloff makes sense, Fuselier says, because Earth's magnetopause isn't spherical. Instead, it has a teardrop shape that's closest to Earth at its nose but farther away everywhere else. So at locations well away from the magnetopause's centerline, even fewer of the exosphere's hydrogen atoms are hanging around to interact with the solar wind. "No exosphere, no ENAs," he explains.
A Versatile Spacecraft
Since its launch, IBEX has also scanned another nearby world, with surprising results. The moon has no atmosphere or magnetosphere, so the solar wind slams unimpeded into its desolate surface. Most of those particles get absorbed by lunar dust. In fact, space visionaries wonder if the moon's rubbly surface has captured enough helium-3, an isotope present in tiny amounts in the Sun's outflow, to serve as a fuel for future explorers.
Yet cosmic chemists have long thought that some solar-wind protons must be bouncing off the lunar surface, becoming ENAs through charge exchange as they do. So does the moon glow in IBEX's scans? Indeed it does, says David J. McComas of Southwest Research Institute in San Antonio, Texas, who serves as the mission's Principal Investigator.
In a report published last year in Geophysical Research Letters, McComas and other researchers conclude that about 10 percent of the solar-wind particles striking the Moon escape to space as ENAs detectable by IBEX. That amounts to roughly 150 tons of recycled hydrogen atoms per year.
Meanwhile, the squat, eight-sided spacecraft continues its primary task of mapping the interactions between the outermost heliosphere and the interstellar medium that lies beyond. McComas and his team are especially eager to learn more about the mysterious and unexpected "ribbon" of ENAs that turned up in the spacecraft's initial all-sky map.
At NASA's Goddard Space Flight Center in Greenbelt, Md., IBEX Mission Scientist Robert MacDowall says the spacecraft should be able to continue its observations through at least 2012. "We weren't sure those heliospheric interactions would vary with time, but they do," he explains, "and it's great that IBEX will be able to record them for years to come."
Susan Hendrix | EurekAlert!
Modeling magma to find copper
13.01.2017 | Université de Genève
What makes erionite carcinogenic?
13.01.2017 | Friedrich-Schiller-Universität Jena
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering