Saturday, September 29, 2007

PHOENIX IS FLYING TO MARS

On Saturday, August 4, 2007 from Cape Canaveral, Florida, a Boeing Delta II rocket launched the Phoenix mission toward the planet Mars. The Phoenix mission is the first chosen for NASA's Scout program, an initiative for smaller, lower-cost, competed spacecraft. The Phoenix mission is named for the resilient mythological bird that was reborn from the ashes of its former life. This is partly because pieces of the mission were created for previous missions. The lander itself was intended for use by 2001's Mars Surveyor lander prior to its cancellation. It also carries a complex suite of instruments that are improved variations of those that flew on the lost Mars Polar Lander.

In the continuing pursuit of water on Mars, the poles are a good place to probe, as water ice is found there. Phoenix will land on the icy northern pole of Mars between 65 and 75 degrees-north latitude. During the course of the 150 sol (Martian day) mission, Phoenix will deploy its robotic arm and dig trenches up to half a meter (1.6 feet) into the layers of water ice. These layers, thought to be affected by seasonal climate changes, could contain organic compounds that are necessary for life.

To analyze soil samples collected by the robotic arm, Phoenix will carry an "oven" and a "portable laboratory." Selected samples will be heated to release volatiles that can be examined for their chemical composition and other characteristics.

Imaging technology inherited from both the Pathfinder and Mars Exploration Rover missions will also be implemented in Phoenix's stereo camera, located on its 2-meter (6.6-foot) mast. The camera's two "eyes" will reveal a high-resolution perspective of the landing site's geology, and will also provide range maps that will enable the team to choose ideal digging locations. Multi-spectral capability will enable the identification of local minerals.

To update our understanding of martian atmospheric processes, Phoenix will also scan the martian atmosphere up to 20 kilometers (12.4 miles) in altitude, obtaining data about the formation, duration and movement of clouds, fog, and dust plumes. It will also carry temperature and pressure sensors.

For more information on the Phoenix mission, visit: http://phoenix.lpl.arizona.edu/

****************************************

THE SKY THIS WEEK

Here are some observing highlights for the week. These events are given from the perspective of observers in the northern hemisphere. No offence to southern-hemisphere folks, it's just because of where I live.

Oct 1, 1:00 to 4:00 AM EDT - The orange-colored planet Mars is less than 7' (7 arcminutes) from 1 Geminorum. (yellow star, spectral type G7III) sometimes called Propus ("forward foot," of Castor, that is) , though that name is mostly used with Eta Geminorum. (1 Geminorum specifics: RA 06hrs 04 07.2min, Dec +23 degrees 15 48, distance 2,800 ly, visual brightness 0.82 magnitude. Mars is shining brighter at -0.1 magnitude).

Oct 3, 6:06 am EDT - Last-quarter Moon

Oct 3 and 4, Early Morning - Mars is less than 1 degree south of the open star cluster M35 (Messier catalog number 35) in Gemini (M35 specifics: RA 06hrs 08.9min, Dec +24 degrees 20 min, distance 2,800 ly, visual brightness 5.3 magnitude).

Oct 5, Before Dawn - Moon is roughly 1 degree north of M44, the Beehive Cluster, also called Praesepe (Latin for "manger"). in the constellation Cancer (M44 specifics: RA 08hrs 40.1min; Dec +19 degrees 59 minutes, distance 577 ly, Visual Brightness 3.7 magnitude.

Oct 7, Early Dawn - A thin crescent Moon is joined by the planets Venus and Saturn and the star Regulus. Western Europe and Morocco will see the Moon occult Regulus. The rest of Europe and Middle East will see it after sunrise, if possible.


Terminology Notes:

arcminute, minute of arc (MOA) - equal to one sixtieth (1/60) of one degree. The symbol is the prime or apostrophe ('), sometimes abbreviated as arcmin or amin.

Degree - one three hundred sixtieth (1/360) of a circle

****************************************

THIS WEEK IN HISTORY

- Astronomy and Science Events -

October 3, 1264 – A comet said to predict death of Pope Urban IV was last seen

October 2, 1608 – The prototype of the modern reflecting telescope was completed by Jan Lippershey

October 4, 1675 - Christian Huygens patented pocket watch

October 1, 1847 - Maria Mitchell discovered a non-naked-eye comet

October 1, 1888 - National Geographic magazine was first published

October 4, 1957 - U.S.S.R. launched Sputnik I, the first artificial Earth satellite

October 1, 1958 – Management of the Vanguard Project was transferred from the Naval Research Laboratory to NASA

October 1, 1990 - Meteor exploded above the Pacific Ocean

October 1, 1962 - US National Radio Astronomy Observatory got a 300' (91m) radio telescope


- Events Noted For Fun -

October 1, 1746 - Bonnie Prince Charlie fled to France (see below)

October 3, 1916 - James Alfred Wight Herriot, veterinarian/novelist

October 1, 1935 – Actress and singer Julie Andrews was born in England

October 1, 1939 - Churchill called the Soviets a "riddle wrapped in a mystery inside an enigma"

October 1, 1942 - Little Golden Books (children books) begins publishing

October 3, 1955 – the children’s television program "Captain Kangaroo" premiered on CBS-TV

October 1, 1971 - Walt Disney World in Orlando, Florida opens

October 1, 1982 - EPCOT Center opens in Orlando, Florida

****************************************

BONNIE PRINCE CHARLIE AND THE SKYE BOAT SONG

Charles Edward Stuart (Bonnie Prince Charlie), the Young Pretender, led the Jacobite uprising, but was defeated by the Duke of Cumberland on Scotland’s Culloden Moor in 1746. Aided by a Jacobite heroine named Flora MacDonald, who disguised him as her serving maid, Charles escaped from Uist to the island of Skye. He was later taken by a French vessel to Morlaix on the coast of Bretagne. Unlike the hope expressed in the song, and despite various political and religious maneuvers that took place over the following forty years, Charles did not return to take up the fight again. He died in Rome in 1788.

The words of the song were written in 1884 by business man, philanthropist, and song writer Sir Harold Boulton, Bart. (baronet) who lived from 1859 to 1935. The first half of the tune (the chorus) is said to be an old sea shanty (in this case, a Gaelic rowing song called "Cuachag nan Craobh," or "The Cuckoo in the Grove"); the second half of the tune (the verse portion) is traditionally attributed to Miss Annie MacLeod (Lady Wilson). The song was not considered a traditional Scottish favorite until recent times. It is sometimes sung as a lullaby in a slow rocking time, or danced as a waltz.

The Skye Boat Song

Chorus:

Speed bonnie boat, like a bird on the wing,
Onward, the sailors cry
Carry the lad that's born to be king
Over the sea to Skye

Loud the winds howl, loud the waves roar,
Thunder clouds rend the air;
Baffled our foe's stand on the shore
Follow they will not dare

(Chorus)

Though the waves leap, soft shall ye sleep
Ocean's a royal bed
Rocked in the deep, Flora will keep
Watch by your weary head

(Chorus)

Many's the lad fought on that day
Well the claymore could wield
When the night came, silently lay
Dead on Culloden's field

(Chorus)

Burned are our homes, exile and death
Scatter the loyal men
Yet, e'er the sword cool in the sheath,
Charlie will come again.

(Chorus)

----------

To review the history, the text, or to listen to the melody, check out this page from the Scottish Folk Music section of “Contemplations from the Marianas Trench - Music and Deep Thoughts” - http://www.contemplator.com/scotland/skyboat.html

To see a GIF image file of the score of the song, or to download an ABC file of the score, visit this page of “The Session” - http://www.thesession.org/tunes/display/3690

****************************************

Sunday, September 23, 2007

Happy Equinox!

Earth's most recent equinox occurred today, September 24, at 9:51 UT (5:51 am EDT). Equinox is the time when the plane sun (the ecliptic) crosses the earth’s equator (also known as the celestial equator). At this time night and day are approximately equal in length. The word equinox literally means “equal night,” suggesting the thought that the length of night and day are equal. Equinox occurs twice each year, or twice in each orbit of the earth. The approximate dates each year are March 21 and September 22. For the hemisphere into which the sun crosses, it is the beginning of spring (the spring or vernal equinox), and for the hemisphere out of which the sun leaves, it is the beginning of autumn, or fall (the autumnal equinox). In the northern hemisphere this year’s autumnal equinox occurred today.

Many people still think that earth’s seasons are caused by changes in the distance of earth around the sun over the course of the year. This is just not the case. While it is true that the orbit of earth is elliptical and that its distance from the sun changes during the year, the difference between the distances is not significant enough to make a difference. For example, this year earth’s closest point to the sun, or earth’s “perihelion,” was January 3 at about 20:00 UT, when the earth-sun distance was 147,093,602 km, and earth’s farthest point from the sun, or earth’s “aphelion,” was July 7 at about 00:00 UT, when the earth-sun distance was 152,097,053 km. The difference between these two is 5,003,451 km, or a 3.3 percent difference.

The phenomenon of seasons (spring, summer, autumn, and winter) is the result of two effects: the tilt of earth’s axis of rotation and the amount of sunlight that reaches earth’s northern and southern hemispheres each day. The earth is tilted about 23.5 degrees (23 degrees 26 minutes) relative to the earth’s orbit around the sun. Most of the time, this tilt causes one hemisphere to experience more daylight than the other. This different can make one hemisphere warmer or colder because of the amount of heat, or thermal energy, that the surface below absorbs and hangs on to during the night that follows.

Aside from the change in temperature, the change in the amount of daily sunlight affects all plant life. Plants use chlorophyll, the green stuff, to capture the sun’s energy and use it, along with carbon dioxide, water and organic nutrients from the soil to make the sugars and starches they use as food. This process is otherwise known as photosynthesis. Over the course of the four seasons the amount of daily sunlight gradually increases and then gradually decreases. When the amount of sunlight is too little for the plant to perform photosynthesis, the plant shuts down its photosynthesis factory and begins to live on its stored food. Many plants even get rid of their solar collectors, or their leaves. When the amount of daily sunlight begins to grow again, the plants put out their solar collectors and crank up the factory. For many people this annual cycle of the leaves is more significant than the rise and fall of temperature.

Ok, enough of the details. You get the idea. A very happy equinox to all!

Saturday, September 22, 2007

Journey to the Dawn of the Solar System

This week should see the launch of NASA’s mission to very the dawn of our solar system. It’s name? Appropriately enough, Dawn. The goals of the Dawn mission are to understand what it was like at the beginning of the solar system, and to understand how the solar system formed. The mission will do this by making an up-close study of “protoplanets.” According to the current theory of planetary formation, protoplanets are the early stage in the development of planets, condensing out of gas clouds surrounding a young star.

The Dawn mission will carefully examine two of the largest protoplanets that remain. They are Ceres, which has recently been classified as a dwarf planet, and the asteroid Vesta. Both of these bodies orbit the sun with many other smaller bodies in the large area between Mars and Jupiter that is called the asteroid belt. These protoplanets, or baby planets, were interrupted in their process of becoming something larger, by the formation of Jupiter, with its tremendous gravity. Ceres, Vesta, and the rest of the bodies in the asteroid belt have followed different evolutionary paths because of the many different processes that operated during the first few million years of the solar system.

The biggest question that the Dawn mission addresses is the role of size and water in determining the evolution of the planets. Ceres and Vesta are the right two bodies with which to address this question, as they are the most massive of the protoplanets, baby planets whose growth was interrupted by the formation of Jupiter. Ceres is very primitive and wet while Vesta is evolved and dry. The instrumentation to be flown is complete, flight- proven and similar to that used for Mercury, Mars, the Moon, Eros and comets. The science team consists of leading experts in the investigation of the rocky and icy planets using proven measurement and analysis techniques.

Dawn has the potential for making many discoveries that could change the way scientists think. For example, Ceres may have active hydrological (water-based) processes leading to seasonal polar caps of water frost, altering our understanding of the interior of these bodies. Vesta may have rocks more strongly magnetized than on Mars, altering our ideas of how and when dynamos arise with important lessons for Mars, Earth and Mercury. Ceres may have a thin, permanent atmosphere distinguishing it from the other minor planets. These are just examples, but even more unexpected discoveries may be made along the journey.

The Dawn mission has three principal scientific drivers. First, to capture the earliest moments in the origin of the solar system, enabling us to understand the conditions under which these bodies formed. Second, to determine the nature of the building blocks from which the terrestrial planets formed and thereby improve our understanding of this formation. Finally, to contrast the formation and evolution of two small bodies that followed very different evolutionary paths, so that we can understand what controls that evolution.

And continuing the theme of “threes,” the Dawn mission accomplishes three goals for NASA. First, the gathered data will provide some context for interpreting the growing observations of extra solar-planetary systems. Second, the mission will provide information on the role of size and water in planetary evolution and form a bridge between the exploration of the rocky inner solar system and the icy outer solar system. Finally, the mission completes the first order exploration of the inner solar system, addressing NASA's goal of understanding the origin and evolution of the solar system and complements NASA’s ongoing investigations of Mercury, Earth and Mars.

Background on Ceres and Vesta

Ceres is the largest asteroid (designated 1 Ceres), the first to be discovered and was recently designated as a dwarf planet. Ceres is named after the Roman goddess of agriculture. It was discovered by Giuseppe Piazzi of the Palermo Observatory on Jan. 1, 1801. Additional observations by Piazzi were cut short due to illness. Carl Friedrich Gauss, at the age of 24, was able to solve a system of 17 linear equations to determine Ceres' orbit and to allow it to be rediscovered, a remarkable feat for this time. As a result within one year of its initial discovery, both Heinrich Olbers and Franz von Zach were able to relocate Ceres. It revolves around the Sun in 4.6 terrestrial years and has a diameter estimated at about 960 km (600 miles).

Vesta, the brightest asteroid (designated 4 Vesta), is named for the ancient Roman goddess of the hearth and is the only asteroid ever visible with the naked eye. Found on March 29, 1807, by Heinrich Olbers, it was the fourth minor planet to be discovered. It is the second most massive and the third largest asteroid. It revolves around the Sun in 3.6 terrestrial years and has an average diameter of about 520 km (320 miles). Its surface composition is basaltic.

Dawn Mission Timeline

At of this writing, the launch is scheduled for Wednesday, September 26, 2007, with a launch window of 7:25 a.m. - 7:54 a.m. EDT. The eight-year Dawn mission timeline is as follows:

September 2007, Launch – Dawn will launch from … and goes into a solar orbit, moving out to the orbit of the planet Mars.

March 2009, Mars gravity assist – Dawn will make a close approach to Mars and steal a bit of inertia from the planet, making the spacecraft go fast enough to move farther out, toward the main asteroid belt.

September 2011, Arrival at Vesta – Dawn will go into orbit around Vesta and will study the body for approximately seven months.

April 2012, Depart Vesta – Dawn will gradually spiral away from Vesta and begin to journey farther out toward Ceres.

February 2015, Arrival at Ceres – Dawn will go into orbit around Ceres and will study the body for approximately five months.

July 2015, End of primary mission – The end of the study of Ceres will mark the completion of the Dawn primary mission. Depending on the health of the spacecraft, the mission might be extended, with possibly other targets to study, but there are no details available at this time.

Please check out the Dawn Mission’s most excellent and informative website:
http://dawn.jpl.nasa.gov/

Tuesday, September 18, 2007

Deep Impact and Stardust Missions Redesignated

On July 3, NASA announced that Deep Impact and Stardust, two successful comet-study spacecraft, would have their useful lives extended. In a coordinated effort, they will make new observations of comets and also characterize extrasolar planets.


Deep Impact Spacecraft Redesignated for “DIXI” and “EPOCh”

The Deep Impact spacecraft will be committed to two science investigations. The first is called the Deep Impact Extended Investigation (DIXI). The second is called Extrasolar Planet Observation and Characterization (EPOCh).

DIXI will involve the flyby of periodic comet 85P/Boethin, which has not been visited previously. This investigation will allow the recovery of some of the science which was lost with the August 2002 failure of the COmet Nucleus TOUR (CONTOUR) mission that was designed to make comparative studies of multiple comets. The Deep Impact spacecraft will be directed to fly by Boethin on December 5, 2008. Boethin was discovered by an amateur astronomer, the Reverend Leo Boethin, on January 4, 1975. Reverend Boethin discovered the comet, and made the first series of observations, from the town of Abra in the Philippines. The comet has a period of 11.225 years and the next perihelion is predicted to occur June 29, 2008. The rest of the orbital elements are as follows: Aphelion distance, 20,7560 AU; Perihelion distance, 1.1143 AU; Semi-major axis, 11.67560 AU; Eccentricity, 0.7777; Inclination, 5.756 degrees.

While en route to Boethin, the spacecraft will be used for the EPOCh investigation to observe several nearby bright stars, watching as known extrasolar giant planets pass in front of their stars and then behind them. The collected data will be used to characterize the giant planets and to determine whether they possess rings, moons, or Earth-sized planetary companions. EPOCh's sensitivity will exceed both current ground and space-based observatory capabilities. EPOCh also will measure the mid-infrared spectrum of the Earth, providing comparative data for future efforts to study the atmospheres of extrasolar planets.


Stardust Spacecraft Redesignated for “NExT”

While DIXI (Deep Impact) heads elsewhere, the Stardust spacecraft is off to visit Deep Impact’s old friend, periodic Comet 9P/Tempel (or Tempel 1). The mission is called New Exploration of Tempel 1 (NExT). This investigation will provide the first look at the changes to a comet nucleus produced after its close approach to the sun. It will also mark the first time a comet has been revisited. NExT will also extend the mapping of Tempel 1, making it the most mapped comet nucleus to date. The mapping will address the major questions of comet nucleus “geology” raised by images of areas where it appears material might have flowed like a liquid or powder. The images were returned by the Deep Impact spacecraft from its encounter with the comet on July 4, 2005. NExT is scheduled to fly by 9P/Tempel 1 on February 14, 2011. Comet 9P/Tempel was discovered April 3, 1867 by German astronomer Ernst Wilhelm Leberecht Tempel, who was working in Marseille. The comet has a period of 5.515 years and the next perihelion is predicted to occur in 2011. The rest of the orbital elements are as follows: Aphelion distance, 4.737 AU; Perihelion distance, 1.506 AU; Semi-major axis, 3.122 AU; Eccentricity, 0.5175; Inclination, 10.5301 degrees.


Background Information

Stardust was launched February 7, 1999. It traveled over 2 billion miles to fly within 150 miles of the comet Wild 2 in January 2004 to bring back samples that may provide new insights into the composition of comets and how they vary from one another. The container with the comet samples returned to Earth in January 2006 while the rest of the spacecraft remained in space.

Stardust Mission Home Page: http://stardust.jpl.nasa.gov/

Deep Impact was launched January 12, 2005. It traveled 268 million miles to Comet Tempel 1. The two-part spacecraft consisted of a larger “flyby” spacecraft carrying a smaller “impactor” spacecraft. The impactor was released July 2 and impacted Tempel 1 at 10:52 pm PDF on July 3 (July 4 EDT). The flyby spacecraft observed the impact and aftermath from 300 miles away, while other spacecraft and ground instruments made observations.

Deep Impact Mission Home Page: http://deepimpact.jpl.nasa.gov/