China and Satellite Hacking Claims

The Earth-observing Terra spacecraft. Credit: NASA

In a post on AllThingsNuclear.org, scientist Laura Grego examines U.S. claims linking the Chinese military to alleged hacking attacks on two Earth observation satellites, and concludes there is very little evidence to back them up.

“Why would China try to hack a low-resolution earth-monitoring satellite, much of whose data are distributed free and freely, and for which system China even has operated a ground station to assist in collecting data?” she writes.

Grego questions whether the incidents were indeed hacking, and says that even if they were, it is unclear what advantage an unauthorised user could obtain from Landsat-7 and Terra, “which are not strategically important or national security-related satellites.”

She further notes that no evidence of Chinese involvement is presented in the draft of the U.S.-China Security and Economic Commission’s annual report to Congress. Greco says the report’s assertion that the incidents “appear consistent with authoritative Chinese military writings” is based on one book by a “marginal figure” in China.

NASA Hubble: First Supernova Companion Star Found

An international team of astronomers has, for the first time, observed a stellar "survivor" to emerge from a double star system involving an exploded supernova.

Supernovae are some of the most significant sources of chemical elements in the universe, and they are at the heart of our understanding of the evolution of galaxies.

In this artist's view the red super-giant supernova progenitor star (left) is exploding after having transferred about 10 solar masses of hydrogen gas to the blue companion star (right).

Image Credit: NASA

Tungurahua volcano, Quito, Ecuador

The Tungurahua volcano spews lava and ash early in the morning 135 km south of Quito, Ecuador

Picture: SILVANA HIDALGO/AFP/Getty Images

NASA JPL MARS Rover Curiosity: Course Excellent, Adjustment Postponed

Excellent launch precision for NASA's Mars Science Laboratory mission has forestalled the need for an early trajectory correction maneuver, now not required for a month or more.

That first of six planned course adjustments during the 254-day journey from Earth to Mars had originally been scheduled for 15 days after the mission's Nov. 26 launch on a United Launch Alliance Atlas V rocket.

Now, the correction maneuver will not be performed until later in December or possibly January.

"This was among the most accurate interplanetary injections ever," said Louis D'Amario of NASA's Jet Propulsion Laboratory, Pasadena, Calif. He is the mission design and navigation manager for the Mars Science Laboratory.

Engineers deliberately planned the spacecraft's initial trajectory to miss Mars by about 35,000 miles (56,400 kilometers).

This precaution protects Mars from Earth's microbes, because the Centaur upper stage of the launch vehicle, which is not thoroughly cleaned the way the spacecraft is, leaves Earth on the same trajectory as the spacecraft. The planned trajectory ensures that the Centaur will not hit Mars.

The launch put the spacecraft on an actual trajectory missing Mars by about 38,000 miles (61,200 kilometers).

Planned trajectory correction maneuvers will put the spacecraft on course and on timing to land at Mars' Gale Crater on Aug. 6, 2012, Universal Time (evening of Aug. 5, Pacific Daylight Time).

The spacecraft experienced a computer reset on Tuesday apparently related to star-identifying software in the attitude control system.

The reset put the spacecraft briefly into a precautionary safe mode. Engineers restored it to normal operational status for functions other than attitude control while planning resumption of star-guided attitude control.

Also on Tuesday, thrusters were used as planned to slow the spacecraft's rotation rate from 2.5 rotations per minute to 2.05 rotations per minute. Telecommunications are active at a downlink rate of 25 kilobits per second.

Electrical output from the cruise stage solar array is 800 watts. Thrusters warmed by catalytic bed heaters were originally warmer than expected, but use of the heaters has been reduced to keep the thrusters at intended temperatures.

As of 9 a.m. PST (noon EST) on Friday, Dec. 2, the spacecraft will have traveled 10.8 million miles (17.3 million kilometers) of its 352-million-mile (567-million-kilometer) flight to Mars, and will be moving at 7,500 mph (12,000 kilometers per hour) relative to Earth and at 73,800 mph (118,700 kilometers per hour) relative to the sun.

NASA Test Firing J-2X Rocket engine - video

NASA conducted a key stability test firing of the J-2X rocket engine Dec. 1, marking another step forward in development of the upper-stage engine that will carry humans farther into space than ever before. (NASA/SSC)



Designing and Building the J-2X Engine

MARS Recon Orbiter: Airbursts trigger dust avalanches

The surface of Mars may be cold and desolate, but it is not unchanging. 

New images show that avalanches of dust scour dozens of Martian sites each year.

Without the abundant water and plate tectonics that keep Earth's surface in motion, the surface of Mars is much slower to change. But in one way it is more active. 

While Earth's atmosphere shields us from asteroids smaller than 30 metres across, which burn up or shatter too high above the ground to have much effect on us, Mars's atmosphere is just 1 per cent the density of Earth's. Even rocks less than a metre across make it to the ground and gouge out craters.

NASA's Mars Reconnaissance Orbiter spots about 20 new craters between 1 and 50 metres across on Mars each year - scars that were not present in earlier images. Now closer scrutiny of these images has found thousands of small avalanches near 16 of the craters.

The avalanches appear as dark streaks on the hilly terrain that surrounds the craters (a similar but more dramatic avalanche is shown in the image). 

They show up only in areas where there is a lot of light-coloured dust on the ground. To form, it seems the surface's dust coating was shaken loose and slid downhill, revealing the darker rocks beneath, says a team led by Kaylan Burleigh of the University of Arizona in Tucson (Icarus, DOI: 10.1016/j.icarus.2011.10.026).

The team carried out computer simulations that showed that, surprisingly, the avalanches do not seem to be caused by meteorites hitting the ground, but by the shock wave generated by a rock's passage through the atmosphere. 

This spreads across an area about a million times larger than the craters. "It was astonishing that a relatively small impact could affect a large area," says team member Jay Melosh of Purdue University in West Lafayette, Indiana.

In one case, a cluster of 20-metre-wide craters is surrounded by thousands of dust avalanches in an area 4 kilometres square. The many small avalanches give the whole area a darker hue, like a giant black eye around the craters - except for a narrow light zone shaped like a curved dagger.

That light zone is telling. As a rock tears through the atmosphere at supersonic speed it generates a shock wave, before triggering a second blast when it hits the ground. 

The team's simulations show that the second shock interferes with the first, reinforcing it in some places and cancelling it out in others. 

Where it is cancelled out, a narrow curved strip of relatively undisturbed ground is left behind - just like the light zone seen around the crater cluster, says Melosh.

The Martian surface may be the best place in the solar system for recording the effects of these shock waves, since fewer impactors are blocked by its atmosphere than on Earth, says Mark Boslough of Sandia National Laboratory in Albuquerque, New Mexico.

ESA Mars Express: Mountains and buried ice

Phlegra Montes is a range of gently curving mountains and ridges on Mars.

They extend from the northeastern portion of the Elysium volcanic province to the northern lowlands.

This image is centred at 33°N/162°E. The High-Resolution Stereo Camera (HRSC) on ESA’s Mars Express collected the data for these images on 1 June 2011 during orbit 9465. The images have a ground resolution of about 16 m per pixel.

Credits: ESA/DLR/FU Berlin (G. Neukum)

A wider contextual image of the region surrounding Phlegra Montes. The smaller rectangle shows the region covered in this Mars Express HRSC image release.

Credits: NASA MGS MOLA Science Team

Read more on this story at ESA Portal