A Shield For Our Solar System: The Ribbon

The heliosphere shields the solar system from 90 percent of energetic cosmic rays — high-speed charged particles that would otherwise bombard the planets and harm life. Understanding more about the heliosphere and its ability to filter out galactic cosmic rays could be critical for assessing the safety of human space travel, Schwadron notes. The new findings may also help predict how the heliosphere varies in shape and size as it moves through the galaxy and encounters regions of space having different densities and magnetic field strengths.

The ribbon found by IBEX, recorded at energies between 200 and 6,000 electron volts, is brightest at about 1,000 electron volts and lies between about 100 and 125 astronomical units from the sun, notes David McComas of the Southwest Research Institute in San Antonio. One astronomical unit is the distance between the Earth and the sun. The atoms recorded by IBEX, which orbits Earth, took a year or two, depending on their energies, to reach the craft from the outer edge of the heliosphere.

The IBEX ribbon runs perpendicular to the direction of the galaxy’s magnetic field at the interstellar boundary, an indication that the field has a much stronger than expected influence on the sun’s environs, report Schwadron and his colleagues. One possibility is that pressure from this external magnetic field has forced particles just inside the heliosphere to bunch together into a ribbon.

Iron and Mercury Not Water on Moon

The Centaur rocket that was deliberately crashed into one of the moon’s southern craters October 9 did in fact kick up a plume, even though the plume was not initially as large as hoped.

The relatively low velocity of the Centaur rocket generated a plume that was difficult to spot — in fact impossible to see by many ground-based telescopes — and smaller than had been predicted, suggests Randy Gladstone of the Southwest Research Institute in San Antonio.

Moments after the impact, as the rocket’s mother spacecraft LCROSS got closer and closer to the crash site of its empty Centaur rocket, the raw images taken by LCROSS showed nothing but darkness.

But enhanced composite images released October 16 do show a faint plume that was not apparent in the raw images.

The enhanced images show the heat flash from the impact, the plume and the creation of a new crater inside Cabeus before LCROSS plunged to its own death 4 minutes after the Centaur, said Anthony Colaprete, LCROSS principal investigator and project scientist at the NASA Ames Research Center in Mountain View, Calif.

The new LCROSS images indicate that the crater forged by the Centaur impact is 28 meters wide. Researchers are still analyzing data taken by the craft’s visible-light and ultraviolet spectrometer to identify the plume’s composition.

In the meantime, far-ultraviolet spectra taken by another craft, the Lunar Reconnaissance Orbiter, as it flew over the impact site shows no obvious signs of water. Instead, the spectra show signs of what may be iron and mercury, says Gladstone, a mission scientist.

Space Station Dodges Orbital Junk

The International Space Station fired its rocket engines to dodge space junk for the first time in five years on Wednesday.

According to a daily NASA status report, the European-built cargo ship Jules Verne docked at the station’s aft end fired its rocket engines in a 5-minute, 2-second maneuver to avoid the potential collision with a piece of orbital trash. The last time the station performed the so-called “Debris Avoidance Maneuver” was on May 30, 2003

Space Ribbon Dicsovery

In a discovery that took astronomers by surprise, the first full-sky map of the solar system's edge—more than 9 billion miles (15 billion kilometers) away—has revealed a bright "ribbon" of atoms called ENAs.

The solar system is surrounded by a protective "bubble" called the heliosphere.

The narrow ribbon snakes along this bubble's inner wall between Voyager 1 and 2, twin spacecraft that have been exploring the solar system's boundary since 2004 and 2007, respectively.

Voyager data, taken from specific regions within the boundary zone, had offered no hint that the ribbon existed. But from its orbit around Earth, NASA's Interstellar Boundary Explorer, or IBEX, spacecraft was able to give researchers a wider view.

IBEX team member Eric Christian, of NASA's Goddard Space Flight Center, compared the Voyager spacecraft to weather stations on Earth.

"Can you imagine trying to determine the weather of the entire Earth from two weather stations? You can't do it," Christian told reporters at a press conference this afternoon.

"IBEX is like our first weather satellite, and it gives us the full picture."

IBEX's map shows that the ribbon measures roughly two billion miles (three billion kilometers) long and several hundred thousand miles wide.

The ribbon isn't visible to people and wouldn't harm spacecraft or humans passing through it, IBEX principal investigator David McComas, of the Southwest Research Institute in Texas, told National Geographic News.

Astronomers aren't yet sure how the ribbon formed, but it's possible that the ribbon could be a result of pressure exerted on the heliosphere by our home galaxy's magnetic field.