Flying Through a Geomagnetic Storm

Glowing green and red, shimmering hypnotically across the night sky, the aurora borealis is a wonder to behold. Longtime sky watchers say it is the greatest show on Earth.It might be the greatest show in Earth orbit, too. High above our planet, astronauts onboard the International Space Station (ISS) have been enjoying an up-close view of auroras outside their windows as the ISS flys through geomagnetic storms.

Auroras are caused by solar activity. Gusts of solar wind and coronal mass ejections strike Earth's magnetic field, rattling our planet's protective shell of magnetism. This causes charged particles to rain down over the poles, lighting up the atmosphere where they hit. The physics is akin to what happens in the picture tube of a color TV.

Incoming particles are guided by Earth's magnetic field to a pair of doughnut-shaped regions called "auroral ovals." There's one around the North Pole and one around the South. Sometimes, when solar activity is high, the ovals expand, and the space station orbits right through them.

Solar Storms Could 'Sandblast' the Moon

Solar storms and associated Coronal Mass Ejections (CMEs) can significantly erode the lunar surface according to a new set of computer simulations by NASA scientists. In addition to removing a surprisingly large amount of material from the lunar surface, this could be a major method of atmospheric loss for planets like Mars that are unprotected by a global magnetic field.

The research is being led by Rosemary Killen at NASA's Goddard Space Flight Center, Greenbelt, Md., as part of the Dynamic Response of the Environment At the Moon (DREAM) team within the NASA Lunar Science Institute.

CMEs are basically an intense gust of the normal solar wind, a diffuse stream of electrically conductive gas called plasma that's blown outward from the surface of the Sun into space. A strong CME may contain around a billion tons of plasma moving at up to a million miles per hour in a cloud many times the size of Earth.

Voyager Crosses Point Of Solar tranquility

The 33 year odyssey of NASA's Voyager 1 spacecraft has reach a distant point at the border of our solar system where there is no external motion of solar wind. Now hurtling toward interstellar space a few 17.4 billion kilometers (10.8 billion miles) from the Sun, Voyager 1 has cross into an region where the velocity of the hot ionized gas, or plasma, emanate straight outward from the Sun has slowed to zero. Scientists think the solar wind has been turned sideways by the force from the interstellar wind in the district between stars. The event is a major milestone in Voyager 1's way through the heliosheath, the turbulent external shell of the Sun's sphere of influence, and the spacecraft's future leaving from our solar system.

"The solar wind has turned the corner," said Ed Stone, Voyager plan scientist based at the California Institute of Technology in Pasadena, Calif. "Voyager 1 is receiving close to interstellar space." Our sun gives off a stream of emotional particles that form a bubble recognized as the heliosphere around our solar system. The solar wind movements at supersonic speed awaiting it crosses a shockwave called the termination shock. At this point, the solar wind radically slows down and heats up in the heliosheath. Launched on Sept. 5, 1977, Voyager 1 crossed the extinction shock in December 2004 into the heliosheath. Scientists have use information from Voyager 1's Low-Energy.

Charged Particle Instrument to assume the solar wind's velocity. When the speed of the charge particles drumming the external face of Voyager 1 matched the spacecraft's speed, researchers know that the net external speed of the solar wind was zero. This happened in June, when Voyager 1 was about 17 billion kilometers from the Sun. Because the velocity can fluctuate, scientists watch four more monthly reading before they were persuaded the solar wind's outward speed really had slowed to zero. Analysis of the data shows the velocity of the solar wind has progressively slowed at a speed of about 20 kilometers per second each year since August 2007, when the solar wind was speeding external at about 60 kilometers per second. The external speed has remain at zero since June.

ARTEMIS - The First Earth-Moon Libration Orbiter

In August 1960, NASA launched its first communications satellite, Echo 1. Fifty years later, NASA has achieved another first by placing the ARTEMIS-P1 spacecraft into a unique orbit behind the moon, but not actually orbiting the moon itself. This type of orbit, called an Earth-Moon libration orbit, relies on a precise balancing of the Sun, Earth, and Moon gravity so that a spacecraft can orbit about a virtual location rather than about a planet or moon. The diagrams below show the full ARTEMIS-P1 orbit as it flies in proximity to the moon. ARTEMIS-P1 is the first spacecraft to navigate to and perform stationkeeping operations around the Earth-Moon L1 and L2 Lagrangian points. There are five Lagrangian points associated with the Earth-Moon system.

The two points nearest the moon are of great interest for lunar exploration. These points are called L1 (located between the Earth and Moon) and L2 (located on the far side of the Moon from Earth), each about 61,300 km (38,100 miles) above the lunar surface. It takes about 14 to 15 days to complete one revolution about either the L1 or L2 point. These distinctive kidney-shaped orbits are dynamically unstable and require weekly monitoring from ground personnel. Orbit corrections to maintain stability are regularly performed using onboard thrusters. After the ARTEMIS-P1 spacecraft has completed its first four revolutions in the L2 orbit, the ARTEMIS-P2 spacecraft will enter the L1 orbit. The two sister spacecraft will take magnetospheric observations from opposite sides of the moon for three months, then ARTEMIS-P1 will move to the L1 side where they will both remain in orbit for an additional three months.

Flying the two spacecraft on opposite sides, then the same side, of the moon provides for collection of new science data in the Sun-Earth-Moon environment. ARTEMIS will use simultaneous measurements of particles and electric and magnetic fields from two locations to provide the first three-dimensional perspective of how energetic particle acceleration occurs near the Moon's orbit, in the distant magnetosphere, and in the solar wind. ARTEMIS will also collect unprecedented observations of the space environment behind the dark side of the Moon – the greatest known vacuum in the solar system – by the solar wind. In late March 2011, both spacecraft will be maneuvered into elliptical lunar orbits where they will continue to observe magnetospheric dynamics, solar wind and the space environment over the course of several years.