Archive for June, 2011

Small Asteroid to Whip Past Earth on June 27, 2011

Sunday, June 26th, 2011

Source – NASA/JPL Near-Earth Objects Program:

Don Yeomans & Paul Chodas
NASA/JPL Near-Earth Object Program Office
June 23, 2011
Updated: June 26, 2011

Trajectory of 2011 MD projected onto the Earth's orbital plane. Note from this viewing angle, the asteroid passes underneath the Earth.

Trajectory of 2011 MD from the general direction of the Sun.

Near-Earth asteroid 2011 MD will pass only 12,300 kilometers (7,600 miles) above the Earth’s surface on Monday June 27 at about 1:00 PM EDT. The asteroid was discovered by the LINEAR near-Earth object discovery team observing from Socorro, New Mexico. The diagram on the left shows the trajectory of 2011 MD projected onto the Earth’s orbital plane over a four-day interval. The diagram on the left gives another view from the general direction of the Sun that indicates that 2011 MD will reach its closest Earth approach point in extreme southern latitudes (in fact over the southern Atlantic Ocean). This small asteroid, only 5-20 meters in diameter, is in a very Earth-like orbit about the Sun, but an orbital analysis indicates there is no chance it will actually strike Earth on Monday. The incoming trajectory leg passes several thousand kilometers outside the geosynchronous ring of satellites and the outgoing leg passes well inside the ring. One would expect an object of this size to come this close to Earth about every 6 years on average. For a brief time, it will be bright enough to be seen even with a modest-sized telescope.

Summer Solstice 2011 – How can you measure the tilt of the Earth?

Wednesday, June 22nd, 2011

This is a little late but still fun to do…

An Interview with John Dobson Jan 2010

Tuesday, June 21st, 2011

Source Wikipedia, the free encyclopedia

John Lowry Dobson (born September 14, 1915) is a popularizer of amateur astronomy. He is most notable for being the promoter of a design for large, portable, low-cost Newtonian reflecting telescopes that bears his name, the Dobsonian telescope. The design is considered revolutionary since it allowed amateur astronomers to build extremely large telescopes. He is less known for his efforts to promote awareness of astronomy (and his unorthodox views of cosmology) through public lectures including his performances of “sidewalk astronomy.” John Dobson is also the co-founder of the amateur astronomical group, the San Francisco Sidewalk Astronomers

Voyager Space Craft’s Still Doing Science after all These Years.

Thursday, June 9th, 2011

The Voyager space probes are now some 9 billion miles from the Sun, and have discovered some interesting facts about the Sun’s Magnetic Field way out there.

NASA/JPL What’s Up for June 2011?

Sunday, June 5th, 2011

Source – NASA:

What’s up for June? Solar system collisions!

NASA’s Spirit Rover Completes Mission on Mars

Sunday, June 5th, 2011

Source – NASA: Jet Propulsion Laboratory, Pasadena, Calif.

May 25, 2011

NASA has ended operational planning activities for the Mars rover Spirit and transitioned the Mars Exploration Rover Project to a single-rover operation focused on Spirit’s still-active twin, Opportunity.

This marks the completion of one of the most successful missions of interplanetary exploration ever launched.

Spirit last communicated on March 22, 2010, as Martian winter approached and the rover’s solar-energy supply declined. The rover operated for more than six years after landing in January 2004 for what was planned as a three-month mission. NASA checked frequently in recent months for possible reawakening of Spirit as solar energy available to the rover increased during Martian spring. A series of additional re-contact attempts ended today, designed for various possible combinations of recoverable conditions.

“Our job was to wear these rovers out exploring, to leave no unutilized capability on the surface of Mars, and for Spirit, we have done that,” said Mars Exploration Rover Project Manager John Callas of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

Spirit drove 4.8 miles (7.73 kilometers), more than 12 times the goal set for the mission. The drives crossed a plain to reach a distant range of hills that appeared as mere bumps on the horizon from the landing site; climbed slopes up to 30 degrees as Spirit became the first robot to summit a hill on another planet; and covered more than half a mile (nearly a kilometer) after Spirit’s right-front wheel became immobile in 2006. The rover returned more than 124,000 images. It ground the surfaces off 15 rock targets and scoured 92 targets with a brush to prepare the targets for inspection with spectrometers and a microscopic imager.

“What’s really important is not only how long Spirit worked or how far Spirit drove, but also how much exploration and scientific discovery Spirit accomplished,” Callas said.

One major finding came, ironically, from dragging the inoperable right-front wheel as the rover was driving backwards in 2007. That wheel plowed up bright white soil. Spirit’s Alpha Particle X-ray Spectrometer and Miniature Thermal Emission Spectrometer revealed that the bright material was nearly pure silica.

“Spirit’s unexpected discovery of concentrated silica deposits was one of the most important findings by either rover,” said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for Spirit and Opportunity. “It showed that there were once hot springs or steam vents at the Spirit site, which could have provided favorable conditions for microbial life.”

The silica-rich soil neighbors a low plateau called Home Plate, which was Spirit’s main destination after the historic climb up Husband Hill. “What Spirit showed us at Home Plate was that early Mars could be a violent place, with water and hot rock interacting to make what must have been spectacular volcanic explosions. It was a dramatically different world than the cold, dry Mars of today,” said Squyres.

The trove of data from Spirit could still yield future science revelations. Years of analysis of some 2005 observations by the rover’s Alpha Particle X-ray Spectrometer, Miniature Thermal Emission Spectrometer and Moessbauer Spectrometer produced a report last year that an outcrop on Husband Hill bears a high concentration of carbonate. This is evidence of a wet, non-acidic ancient environment that may have been favorable for microbial life.

“What’s most remarkable to me about Spirit’s mission is just how extensive her accomplishments became,” said Squyres. “What we initially conceived as a fairly simple geologic experiment on Mars ultimately turned into humanity’s first real overland expedition across another planet. Spirit explored just as we would have, seeing a distant hill, climbing it, and showing us the vista from the summit. And she did it in a way that allowed everyone on Earth to be part of the adventure.”

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rovers Opportunity and Spirit for the NASA Science Mission Directorate, Washington. For more about the rovers,
see: and

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.