Damaged Genesis Yields Data on Solar Wind
The goal of NASA's Genesis mission was to collect samples of the solar wind and return them to Earth for study. The Genesis spacecraft spent 27 months in space, gathering tiny particles from different types of solar wind. It then returned to Earth and ejected its sealed sample capsule for Earth re-entry and a gentle airborne recovery by helicopter. Unfortunately the planned parachute-capture of the capsule was not possible because the parachute failed to deploy. The sad result was the creation of a new small crater in the Utah desert. Observers of the crash were initially devastated, but the mission team soon realized that data could still be salvaged, though more slowly and with more effort.
The results, picked from millimeter-sized shards of the spacecraft's detectors, provide a snapshot of the early solar system, and will feed into models that outline how our planet’s atmosphere evolved.
The team originally hoped they could publish a series of papers within a year of the return. It has taken much longer, but as of late October a series of four papers had been published in Space Science Reviews and a fifth paper appeared the week of October 14 in Science. In addition, a preliminary paper was published last year.
The team remains hopeful that they will soon be able to complete the main goal of their original mission: solving the mystery of the unique isotopic signature of different objects in our galaxy.
The recent paper in Science contains a study of the ratio of different isotopes of neon and argon obtained from samples of three types of solar wind: fast, slow, and coronal mass ejections from the sun’s surface. The researchers conclude that these ratios are essentially the same in all three types of wind. This is good news: it indicates that the elements of main interest to the researchers have the same isotopic signature in the solar wind as in the sun itself.
That’s useful because the outer layer of the sun is thought to provide a picture of isotopic ratios in the very early solar system, before stars or planets were formed. Scientists had previously been concern that there would be a difference between the compositions of the solar wind and the sun itself.
The isotopic ratios of neon and argon are not in themselves very surprising — scientists already had a fairly good measure of these values from previous missions, including one low-tech scheme during the Apollo program in which a screen was laid out on the Moon to collect solar-wind samples. But they improve by a factor of 60 the precision with which the argon isotope ratio is known. This will be useful for researchers who model the early solar system to work out processes such as how Earth’s atmosphere formed.
As expected, the Genesis samples have a heavy contamination of Earth dirt and air. But surprisingly, the grit that is proving most problematic for the team at this point is a fine layer of lubricants and other craft-building materials that coated the samples. The coating was expected, but it is proving tricky to deal with.
Earth contamination can be separated from the samples mainly because the solar wind particles penetrated deep into the collector cells, a depth of approximately 40 nanometers.
The study of neon and argon was not affected as much by Earth contamination because dirt and air on Earth contain relatively little neon and argon.
The team remains hopeful that they will be able to get results on oxygen and nitrogen isotopes from the mission. To do this, they plan to examine a collecting dish that, although banged up and dirtied by the landing, seems to have succeeded in gathering up enough of these elements for measurement.
Scientists are interested in nitrogen because on the Moon, isotopes of this element vary greatly between the collected soil samples, even though all nitrogen is thought to come from the solar wind. Researchers want to know the reason for this variation.
Oxygen isotopes are even odder, as they seem to have unique ‘fingerprint’ values in different types of objects. For example if given a rock sample, scientists can measures oxygen isotopes and determine whether it is from Earth or space or the Moon. But put they are still trying to understand why. By knowing the value in the Sun, and hence the early Solar System, they expect to pin down the reason for this oddity.
Some are even confident that with more work and a few more years, they will also get oxygen and nitrogen.
To learn more about the Genesis mission, visit these websites:
MARS IS COMING, PART 4
As the December 24 opposition approaches, please enjoy this fourth installment on the Red Planet Mars.
The Atmosphere (Part 2)
Quick Atmospheric Temperature Overview:
- Surface: Cyclic temperatures range from approximately 189 K (-119 °F, -84 °C) to 240 K (-28 °F, -33 °C)
- Lower atmosphere: Altitude of a few kilometers up to 40 km (a few miles up to 25 miles). Temperature decreases at a rate of .5 K per km.
- Tropopause: 40 km to 100 km (25 miles to 60 miles).
- Above 100 km (above 60 miles): Average temperature of about 300 K (80 °F, 27 °C).
Below about 125 km (80 miles), the Martian atmosphere is composed of 95.5% carbon dioxide and small amounts of nitrogen, water vapor and argon, with trace amounts of other gases. To put some of these components in perspective, carbon dioxide is responsible for the Greenhouse Effect and is used for carbonation in beverages, nitrogen is a crucial element in DNA, and argon is used to make blue neon light blubs.
Even though the Martian atmosphere is very thin by comparison to Earth’s, it is still very dynamic and very complex. The relation of temperature and pressure to the altitude--sometimes called the vertical structure of the atmosphere--is determined by two factors. One is a complicated balance of several mechanisms that spread energy through the atmosphere. The other is the way in which the sun's energy is introduced into the atmosphere and then lost by radiation to space.
In the lower atmosphere, the vertical structure is controlled by a combination of almost-pure carbon dioxide and the large amount of suspended dust. Carbon dioxide radiates energy efficiently at the colder (relative to Earth) Martian temperatures, so the atmosphere responds quickly to changes in the amount of solar radiation it receives. The suspended dust absorbs large quantities of heat directly from sunlight and distributes the energy throughout the lower atmosphere.
Like Earth, Martian surface temperatures depend on the latitude. But the temperatures fluctuate over a wider range from day to night. At the Viking 1 and Pathfinder landing sites, both of which are about 20° N latitude, the temperatures at roughly human height above the surface regularly varied from a low near 189 K (-119 °F, -84 °C) just before sunrise to a high of 240 K (-28 °F, -33 °C) in the early afternoon—an amazing range of about 51 K or 51 °C or 91 °F. This temperature swing is much greater than that of the desert regions on Earth. The variation is greatest very close to the ground where the thin, dry atmosphere allows the surface to radiate its heat quickly during the night. During dust storms this ability is restricted, and the temperature swing is reduced. At altitudes above a few kilometers, the daily variation is damped out, but other cyclic changes appear throughout the atmosphere because of the sun’s energy. The temperature and pressure cycles are sometimes called “tides” because they are regular, periodic, and synchronized with the position of the sun. These tides give the Martian atmosphere a very complex vertical structure.
Up to about 40 km (25 miles) the atmosphere gradually cools at a rate of .5 K per km.
Beginning at that level, called the tropopause, the temperature becomes a roughly constant 140 K (-210 °F, -130 °C). This was measured by the Viking and Pathfinder spacecraft as they descended through the atmosphere. Before these measurements were taken, scientists thought the tropopause began at about 15 km (9 miles), and the rate of temperature drop leading up to that altitude was thought to be near 5 K per km. The large amount of dust suspended in the atmosphere is thought to be responsible for the differences.
Above 100 km (60 miles), the structure of the atmosphere is determined by the tendency of the heavier molecules to settle below the lighter ones. This diffusive separation process overcomes the tendency of turbulence to mix all the constituents together. At these high altitudes, absorption of ultraviolet light from the sun dissociates and ionizes the gases and leads to complex sequences of chemical reactions. The top of the atmosphere has an average temperature of about 300 K (80 °F, 27 °C).
Meteorology and atmospheric dynamics
The global pattern of atmospheric circulation on Mars appears similar to that of Earth, but the root causes are very different. Among these differences are the atmosphere's ability to adjust rapidly to local conditions of solar heat input; the lack of oceans, which on Earth have a large resistance to temperature changes; the great range in altitude of the surface; the strong internal heating of the atmosphere because of suspended dust; and the seasonal deposition and release of a large part of the Martian atmosphere at the poles.
The only direct measurements of wind speeds were made by the Viking and Pathfinder landers. Near-surface winds at the landing sites were usually regular in behavior and generally light. Average speeds were typically less than 2 meters per second (4.5 miles per hour), although gusts up to 40 meters per second (90 miles per hour) were recorded. Other observations, including streaks of windblown dust and patterns in dune fields and in the many varieties of clouds, provide additional clues about surface winds.
Global circulation models, which incorporate all the factors understood to influence the behavior of the atmosphere, predict that the winds are strongly needed to create the Martian seasons because of the large horizontal temperature gradients associated with the edge of the polar caps in the fall and winter. Strong jet streams with eastward velocities above 100 meters per second (225 miles per hour) form at high latitudes in winter. Atmosphere circulation is less dramatic in spring and fall, when light winds predominate everywhere. On Mars, unlike on Earth, there is also a relatively strong north-south circulation that transports the atmosphere to and from the winter and summer poles. The general circulation pattern is occasionally unstable and exhibits large-scale wave motions and instabilities: a regular series of rotating high- and low-pressure systems was clearly seen in the pressure and wind records at the Viking lander sites.
Smaller-scale motions and circulations, driven both by the sun and by surface topography, are found everywhere. For example, at the Viking and Pathfinder landing sites, the winds change in direction and speed throughout the day in response to the position of the sun and the local slope of the land.
Turbulence is an important factor in raising and maintaining the large quantity of dust found in the atmosphere. Dust storms tend to begin at certain locations in the southern hemisphere during the southern spring and summer. Activity is at first local and strong (for reasons yet to be understood), and large amounts of dust are thrown high into the atmosphere. If the amount of dust reaches a critical quantity, the storm quickly intensifies, and dust is carried by high winds to all parts of the planet. In a few days the storm hides the entire surface, and visibility is reduced to less than 5 percent of normal. The strengthening process is short-lived and the atmosphere begins to clear almost immediately, becoming normal typically in a few weeks.
Next Time: "The Polar Caps"
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
THE SKY THIS WEEK
Nov 24, 9:30 AM EST - Full Moon. Called the "Beaver Moon" or "Snow Moon," this was the time to set beaver traps before the swamps froze, in order to ensure a supply of winter furs. Others suggest the name refers to the fact that beavers were actively preparing for winter. This full moon is also sometimes called the "Frosty Moon."
Nov 24 – The planet Uranus is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
Nov 27 – The planet Mars is 1.7° south of the Moon
Nov 28 – The planet Venus is 4° north of the star Spica
Nov 30 - the star Regulus 0.3° north of the Moon, an occultation as seen from some locations. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Dec 1, 7:44 A.M. EST - Last Quarter Moon
Dec 1 – The planet Saturn is 2° north of Moon
SPACE EXPLORATION THIS WEEK
Nov 30 - Ulysses, begins its third north polar pass of the sun
THIS WEEK IN HISTORY
Nov 26, 1965 - Asterix 1 Launch, France's 1st Satellite Launch
Nov 26, 1999 - Discovery of SAU 005 & 008, two Mars Meteorites
Nov 27, 1701 - Birthday of Anders Celsius, Swedish astronomer (1701-1744). Celsius developed a thermometer which had 100 points between the freezing point (100) and boiling point (0) of water. The scale was later reversed by Carolus Linnaeus so that the freezing point was 0 and the boiling point was 100. This temperature scale is named in his honor.
Nov 27, 1971 - Mars 2, Mars Orbit Insertion
Nov 28, 1700 - Birthday of Nathaniel Bliss, British astronomer, succeeded James Bradley to be the fourth Astronomer Royal, serving from 1762 until his death in 1764.
Nov 28, 1964 - Mariner 4 Launch, Mars Flyby Mission
Nov 29, 1961 - Mercury 5 Launch with Enos the Chimpanzee
Nov 29, 1967 - Wresat 1 Launch, Australia's 1st Satellite, 40th Anniversary
Nov 29, 2000 - Discovery of Y000593 Meteorite, a Mars Meteorite
Nov 30, 1954 - Sylacauga Meteorite Fall, Hit Woman
Dec ??, 2000 - Discovery of NWA 817 Meteorite, a Mars Meteorite
Dec 1, 1960 - Sputnik 6 Launch, Carried Two Dogs: Pchelka & Mushka
According to a 1580 entry in the Stationers’ Register, license was given to a Richard Jones to print “A new Northern Dittye of the Lady Green-Sleeves.” This was one of the first references to the song known today as “Greensleeves.” The other reference appeared the same year, by Edward White, entitled "A ballad, being the Ladie Greene Sleeves Answere to Donkyn his frende." The earliest surviving lyrics are in a collection called A Handful of Pleasant Delights (1584). The actual “Greensleeves” tune first appeared in 1652.
Many stories have developed around the song. According to legend, King Henry VIII of England (1491-1547) wrote the song for Anne Boleyn during their courtship, around 1530. However, this has never been proven and is probably not true. But it is also said that Henry’s daughter Queen Elizabeth I danced to the song. The song’s tune was used as the basis for a number of other lyrics, including a political ballad of the day. Even William Shakespeare mentioned “Greensleeves” twice (in Act Two and Act Five) in his play, “The Merry Wives of Windsor.”
The lyrics show the song to be a plea from a 16th century gentleman to his bored mistress. Here are some of the recorded lyrics for the song.
Alas, my love you do me wrong
To cast me off discourteously
And I have loved you so long
Delighting in your company
Greensleeves was all my joy
Greensleeves was my delight
Greensleeves was my heart of gold
And who but my Lady Greensleeves.
I have been ready at your hand
to grant whatever you would crave;
I have both wagered life and land
Your love and good will for to have
I bought the kerchers to thy head
That were wrought fine and gallantly
I kept thee both at board and bed
Which cost my purse well favouredly.
Greensleeves, now farewell! adieu!
God I pray to prosper thee;
For I am still thy lover true
Come once again and love me.
One of the tune’s early appearances in a hymn was entitled “The Old Yeare Now Away Is Fled.” Then about 1865, English poet and lay theologian William Chatterton Dix published a poem entitled "The Manger Throne." Dix was already known for other carols, including "As With Gladness Men of Old" (1859). Portions of Dix’s new poem were later adapted for the tune "Greensleeves," creating the carol that we know as "What Child Is This?" It is not known who combined the words with the tune, but it may have been John Stainer (1840-1901), since Stainer wrote a harmonization for the song. Stainer published the song in his 1871 collection entitled Christmas Carols New and Old. Below is the text from that publication.
What Child Is This
What Child is this who, laid to rest
On Mary’s lap is sleeping?
Whom angels greet with anthems sweet,
While shepherds watch are keeping?
This, this is Christ the King,
Whom shepherds guard and angels sing;
Haste, haste, to bring Him laud,
The Babe, the Son of Mary.
Why lies He in such mean estate,
Where ox and ass are feeding?
Good Christians, fear, for sinners here
The silent Word is pleading.
Nails, spear shall pierce Him through,
The cross be borne for me, for you.
Hail, hail the Word made flesh,
The Babe, the Son of Mary.
So bring Him incense, gold and myrrh,
Come peasant, king to own Him;
The King of kings salvation brings,
Let loving hearts enthrone Him.
Raise, raise a song on high,
The virgin sings her lullaby.
Joy, joy for Christ is born,
The Babe, the Son of Mary.
To review some the history, the text, or to listen to the melody, check out this pages from the "Songs of England" section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" - http://www.contemplator.com/england/grenslevs.html
To see and hear more on the hymn, “"What Child Is This?" visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/w/h/whatcist.htm