Astronomy with the Plymouth Astronomical Society ( UK )

ASTRO NEWS BRIEFS:

PHOENIX MARS LANDER EXPLORING THE ARCTIC PLAIN OF MARS.

Mission Features.

NASA Phoenix Mission Ready for Mars Landing05.13.08 The landing site chosen for NASA's Mars Phoenix Lander is much farther north than the sites where previous spacecraft have landed on Mars.

NASA's Phoenix Mars Lander is preparing to end its long journey and begin a three-month mission to taste and sniff fistfuls of Martian soil and buried ice. The lander is scheduled to touch down on the Red Planet May 25.

Phoenix will enter the top of the Martian atmosphere at almost 13,000 mph. In seven minutes, the spacecraft must complete a challenging sequence of events to slow to about 5 mph before its three legs reach the ground. Confirmation of the landing could come as early as 7:53 p.m. EDT.

"This is not a trip to grandma's house. Putting a spacecraft safely on Mars is hard and risky," said Ed Weiler, associate administrator for NASA's Science Mission Directorate at NASA Headquarters in Washington. "Internationally, fewer than half the attempts have succeeded."

Rocks large enough to spoil the landing or prevent opening of the solar panels present the biggest known risk. However, images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, detailed enough to show individual rocks smaller than the lander, have helped lessen that risk.

"We have blanketed nearly the entire landing area with HiRISE images," said Ray Arvidson of Washington University in St. Louis, chairman of the Phoenix landing-site working group. "This is one of the least rocky areas on all of Mars and we are confident that rocks will not detrimentally impact the ability of Phoenix to land safely."

Phoenix uses hardware from a spacecraft built for a 2001 launch that was canceled in response to the loss of a similar Mars spacecraft during a 1999 landing attempt. Researchers who proposed the Phoenix mission in 2002 saw the unused spacecraft as a resource for pursuing a new science opportunity.

Earlier in 2002, NASA's Mars Odyssey orbiter discovered that plentiful water ice lies just beneath the surface throughout much of high-latitude Mars. NASA chose the Phoenix proposal over 24 other proposals to become the first endeavor in the Mars Scout program of competitively selected missions. "Phoenix will land farther north on Mars than any previous mission," said Phoenix Project Manager Barry Goldstein of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

"The Phoenix mission not only studies the northern permafrost region, but takes the next step in Mars exploration by determining whether this region, which may encompass as much as 25 percent of the Martian surface, is habitable," said Peter Smith, Phoenix principal investigator at the University of Arizona, Tucson.

The solar-powered robotic lander will manipulate a 7.7-foot arm to scoop up samples of underground ice and soil lying above the ice. Onboard laboratory instruments will analyze the samples. Cameras and a Canadian-supplied weather station will supply other information about the site's environment.

One research goal is to assess whether conditions at the site ever have been favorable for microbial life. The composition and texture of soil above the ice could give clues to whether the ice ever melts in response to long-term climate cycles. Another important question is whether the scooped-up samples contain carbon-based chemicals that are potential building blocks and food for life.

The Phoenix mission is led by Smith with project management at JPL. The development partnership is with Lockheed Martin, Denver. International contributions are from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; the Max Planck Institute, Germany; and the Finnish Meteorological Institute.

For more about the Phoenix mission on the Web, visit:

http://www.nasa.gov/phoenix

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Some Highlights for 2008

Tour May's Sky — By Ear and Eye!
May 1, 2008by the Editors of Sky & Telescope

Use an MP3 player to listen to SkyandTelescope.com's Sky Tour Podcasts.
S&T: Lauren Darby.
Since new Moon falls on May 5th, the evening stars won’t have to compete with bright moonlight during the first part of the month. That goes for planets too, and there are three easy ones in view right now.

This month Mercury makes its best showing in the evening sky all year. But, like the tricky Roman messenger and liquid metal of the same name, Mercury is elusive and slippery. It sinks from view soon after sunset. You’ll have your best chance from May 5th to about the 20th.

Mars is nearing the end of a long-running appearance in the evening sky that began late last year. It's near Castor and Pollux, the Twins of Gemini. Higher up is a pair of obvious stars that seem unusually close together. The brighter one is the planet Saturn. Next to it is Regulus, the brightest star in Leo.

To get a personally guided tour of these sights and others, hosted by Kelly Beatty, S&T's Executive Editor, download this month's audio sky tour to your iPod or other handheld device — or just use your computer to play it.

Go to Sky Tour Podcasts.

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This Week's Star and Planet Roundup.

Saturday, May 17.

How low can you see to your north horizon? That's where you'll find W-shaped Cassiopeia around 10 or 11 p.m. this week. If you're far enough north, that is! From the latitudes of Atlanta, Houston, and San Diego, part of the Cassiopeia W will be below your horizon. From South Florida, the W goes below the horizon completely.

Sunday, May 18.

Face southeast after dusk and look very high for bright Arcturus, 37 light-years away. Look low in the northeast for equally bright Vega, 25 light-years away. These are the two brightest stars of late spring and summer. Their nearness is part of the reason why; most naked-eye stars are typically 100 to more than 1,000 light-years distant.

Monday, May 19.

Full Moon (exact at 10:11 p.m. EDT).

This evening Mars skims just north of Eta Cancri, magnitude 5.3. They'll be less than 3 arcminutes apart during evening twilight in the Eastern time zone, from about 8:00 to 9:30 p.m. EDT.

Tuesday, May 20.

The bright Moon shines low in the southeast this evening. Look above it for orange-red Antares and other stars of upper Scorpius.

The red long-period variable stars RS Librae and RS Scorpii should be at maximum light (7th or 8th magnitude) this week.

Wednesday, May 21.

The sky right after nightfall is again moonless, so observers in the southernmost US, the tropics, and the Southern Hemisphere have a window of darkness to try for Comet Boattini. It has brightened more than expected to about 6th magnitude. This week it's crossing northern Pyxis. See our article and finder chart.

For skywatchers in Europe, Africa, and on the east coast of the Americas, Jupiter is without a visible moon for 18 minutes late tonight or early Thursday morning — a rare event. See our article.

Thursday, May 22.

Saturn is at eastern quadrature, 90° east of the Sun.

Tonight Mars passes right between a pair of 6th-magnitude stars in the Beehive cluster, from about 11:30 to 12:30 p.m. Pacific Daylight Time. Even if Mars won't be in view for you that late, you can still use a telescope earlier in the evening to watch the planet slowly moving. See the map and article in the May Sky & Telescope, page 72.

Friday, May 23.

Mars skims even closer north of another Beehive star, this one magnitude 6.9, around 9 p.m. Eastern Daylight Time. They'll be only about 16 arcseconds apart when closest — about three Mars diameters. Use high power to see through the planet's glare.

Early risers Saturday morning will find Jupiter below the waning gibbous Moon in the south.

Saturday, May 24.

A small telescope will always show Titan, Saturn's largest and wildest moon. Tonight Titan is four ring-lengths to Saturn's east. A guide to identifying all six of Saturn's satellites that are sometimes visible in amateur scopes is in the May Sky & Telescope, page 60.


THIS WEEK'S PLANET ROUNDUP.

To your eyeball, a telescope is doing well if it just shows Mercury's phase clearly. Centuries of astronomers couldn't distinguish surface markings reliably enough to find the planet's correct rotation period. But infrared imaging and video-frame stacking have brought Mercurian surface features in range of amateurs.

MERCURY, is still up in evening twilight, but it's fading fast now: from magnitude +0.6 on May 16th to +2.1 on the 24th. So look for it early in the week. It's fairly low in the west-northwest as twilight deepens.

VENUS, is hidden in the glare of the Sun. It will stay there for months.

MARS, (magnitude +1.4, in Cancer) shines high in the west after dark, off to the upper left of the Castor-and-Pollux couple. Each week Mars is moving farther away from them and closer to the Saturn-and-Regulus couple, still well off to Mars's upper left. They'll meet up for a close get-together in early July.

On the evenings of May 22nd and 23rd, Mars is right inside the Beehive star cluster.

JUPITER, (magnitude –2.5, in eastern Sagittarius) rises around midnight daylight saving time, left of the Sagittarius Teapot. It's highest in the south before dawn.

SATURN, glows high in the southwest after dark, just 2.4° from fainter REGULUS, (magnitude +1.4). They're quite the eye-catching couple. Each week now, they're gradually pulling a little farther apart.

This week Saturn is at eastern quadrature, 90° east of the Sun. So this is when its shadow is cast most sideways onto its rings. See our Saturn observing guide in the April Sky & Telescope, page 66.

URANUS and NEPTUNE, (magnitudes 6.0 and 8.0, respectively, in Aquarius and Capricornus) are in the east and southeast just before dawn.

PLUTO, (magnitude 14.0, in northwestern Sagittarius) is well up in the southeast after midnight. If you've got a big scope and ambition to match, use our article and finder chart.

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FOR ALL OF YOUR TELESCOPIC NEEDS CONTACT,

EVERGREEN OPTICS - UK TELESCOPES, based in POWYS.

UK TELESCOPES, Discount telescope and binocular store, official suppliers of Konus, Meade, Celestron and Sky Watcher

See web site address below under Useful Links.

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PAS. wishes to acknowledge Sky & Telescope magazine, from which much of this information is drawn.
If you wish to contact the Chairman or Secretary of PAS. you can use the website address or telephone Plymouth 338491, or 211799.
You can also e-mail to...oakmount12@aol.com

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NB. THE PLYMOUTH ASTRONOMICAL SOCIETY IS NOW INTO ITS SUMMER BREAK. MEETINGS WILL RESUME ON THE 12TH. SEPTEMBER 2008.

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The Plymouth Astronomical Society meetings are held at the Glynis Kingham Centre, Alfred St.(off Lockyer St.) on the second Friday of each month, starting at 7:30pm.
Membership costs £14:00. pa.
Casual visitors are asked to pay £2:00 at the door.

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Usefull Links.

UK TELESCOPES
ISS. Tracking
Sky and Telescope