Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2003 August 6 
Posted on 08/06/2003 3:12:42 AM PDT by petuniasevan
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2003 August 6
Explanation: Why is peculiar galaxy Centaurus A so dusty? Dramatic dust lanes that run across the galaxy's center mark Cen A. These dust lanes are so thick they almost completely obscure the galaxy's center in visible light. This is particularly unusual as Cen A's red stars and round shape are characteristic of a giant elliptical galaxy, a galaxy type usually low in dark dust. Cen A, also known as NGC 5128, is also unusual compared to an average elliptical galaxy because it contains a higher proportion of young blue stars and is a very strong source of radio emission. Evidence indicates that Cen A is likely the result of the collision of two normal galaxies. During the collision, many young stars were formed, but details of the creation of Cen A's unusual dust belts are still being researched. Cen A lies only 13 million light years away, making it the closest active galaxy. Cen A spans 60,000 light years and can be seen with binoculars toward the constellation of Centaurus.
| Right Ascension | 13 : 25.5 (h:m) |
|---|---|
| Declination | -43 : 01 (deg:m) |
| Distance | 15000.0 (kly) |
| Visual Brightness | 7.0 (mag) |
| Apparent Dimension | 18 x 14 (arc min) |
One needs to be in the southernmost part of the USA to have a chance of seeing Cen A; at my latitude it's barely 3 degrees above the horizon at best. If you're down around Miami FL, Cen A will be as much as 21 degrees above the southern horizon. Midnight culmination occurs about May 3rd.
Hubble composite image of the central regions of Cen A:
From Astronomynow/Spaceflightnow:
'Phoenix' lander headed for Martian North Pole
UNIVERSITY OF ARIZONA-TUCSON NEWS RELEASE
Posted: August 4, 2003
 The Phoenix lander on Mars. Credit: NASA/JPL/LPL |
NASA today announced that it has selected the University of Arizona "Phoenix" mission for launch in 2007 as what is hoped will be the first in a new line of smaller competed "Scout" missions in the agency's Mars Exploration Program.
Peter H. Smith of the UA Lunar and Planetary Laboratory heads the Phoenix mission, named for the mythological bird that is repeatedly reborn of ashes. The $325 million NASA award is more than six times larger than any other single research grant in UA history. The Phoenix mission Science Operations Center will be located in Tucson. Two instruments will be built at the UA, so about $50 million will remain at the university.
"The selection of Phoenix completes almost two years of intense competition with other institutions," Smith said. "I am overjoyed that we can now begin the real work that will lead to a successful mission to Mars. Our large public outreach and educational programs will be nationwide, but activities will especially involve the Tucson community. Our doors will be open to the public throughout the development and flight of the Phoenix bird."
Phoenix is a partnership between universities, NASA centers, and the aerospace industry. The science instruments and operations will be a UA responsibility. The NASA Jet Propulsion Lab in Pasadena, Calif., will manage the project and provide mission design. Lockheed Martin in Denver will build and test the spacecraft. Canadian partners will provide the meteorological instrumentation, including an innovative laser-based sensor.
Phoenix has the scientific capability "to change our thinking about the origins of life on other worlds," Smith said. "Even though the northern plains are thought to be too cold now for water to exist as a liquid, periodic variations in the martian orbit allow a warmer climate to develop every 50,000 years. During these periods the ice can melt, dormant organisms could come back to life, (if there are indeed any), and evolution can proceed. Our mission will verify whether the northern plains are indeed a last viable habitat on Mars."
LPL Director Michael J. Drake said, "Phoenix has the potential to be the smoking gun for the evolution of life elsewhere in the universe. While it will not directly seek to detect life, it will look for complex organic molecules. If they are there, they are hinting strongly at present or past life.
"Detection of complex organics will drive all future Mars exploration, and the Lunar and Planetary Lab will play a prominent role. The discovery that we are not alone in the universe, that science fiction of Star Trek may in fact be science fact, will change the way humanity thinks about itself. The existence of even primitive life forms on Mars raises the probability of advanced life elsewhere, and emphasizes our commonality rather than our differences."
"The selection of Phoenix as the first Mars Scout mission is a tribute to the extraordinary talents and efforts of Peter Smith, William Boynton, and the entire team at the Lunar and Planetary Laboratory, and to the high quality of our partners at JPL and Lockheed Martin," Drake said. "This mission, like few others, has the potential to change the way humanity thinks about itself."
Drake predicts that the Phoenix project will have a $120 million economic impact on Tucson during the next few years. "No previous UA project has had the economic impact on Tucson that this mission will have," he said. "People, especially legislators, usually don't think about the economic impact of the university on our city and state. They regard the university as a consumer of tax dollars rather than a generator of net wealth. But even before the Phoenix mission, for the state's annual investment of $2.5 million in the Lunar and Planetary Lab, the state realized an annual return of $15 million in federal research dollars."
UA Vice President for Research Richard Powell said, "This is a tremendous accomplishment for the faculty and students of our Lunar and Planetary Laboratory. Winning this major competition shows the confidence NASA has in the University of Arizona's scientific capabilities and ability to manage large, critical programs. Very few academic institutions can design, construct, and deliver space-qualified technology on time and within budget. We are proud to have some of the world's top scientists in this field at the University of Arizona and are excited about the unique educational experience our students will receive while working on this project."
"The Lunar and Planetary Laboratory has a distinguished track record of planetary exploration," said College of Science Dean Joaquin Ruiz. "Peter Smith, and William Boynton have an enviable record of successful Mars mission instruments. They delivered information that made us re-think the evolution of the red planet. NASA's selection of our Lunar and Planetary Laboratory for this important mission is a further indication of the extraordinary research done by our institution in planetary sciences.".
The mission
The lander for Phoenix was built and being tested to fly as part of the 2001 Mars Surveyor Program, but the program was canceled after the Mars Polar Lander was lost upon landing near Mars' south pole in December 1999. Since then, the 2001 lander has been stored in a clean room at Lockheed Martin in Denver, managed by NASA's new Mars Exploration Program as a flight asset.
Renamed Phoenix, it will carry improved versions of UA panoramic cameras and a thermal evolved gas analyzer (TEGA) from the ill-fated Mars Polar Lander, as well as experiments that had been built and delivered for the 2001 Mars Surveyor Program, including a Jet Propulsion Laboratory trench-digging robot arm and a chemistry-microscopy instrument (MECA).
"The science instruments that Phoenix brings to Mars are chosen for their ability to analyze the ice and soils of the arctic region," Smith said.
The mission has two goals. One is to study the geologic history of water, the key to unlocking the story of past climate change. Two is to search for evidence of a habitable zone that may exist in the ice-soil boundary, the "biological paydirt."
The science payload includes a descent imager, stereo panoramic camera, robotic arm, thermal evolved gas analyzer, mass spectrometer, optical and atomic force microscopes, electrical and thermal sensors, a wet chemistry laboratory for soil analysis, and a suite of meteorological instruments that includes a lase-based system for studying atmospheric phenomena including dust devils.
"No spacecraft has ever returned data from either polar region, yet they are known from remote sensing to be critical to the seasonal transport of water and carbon dioxide," Smith said.
There may be as much as 80 percent by volume water ice within a half-meter (20 inches) beneath the surface at Mars' north polar region, UA planetary scientist William Boynton and colleagues predict based on results from their Gamma Ray Spectrometer (GRS) experiment on Mars Odyssey. Boynton heads the GRS experiment. The GRS team detected large amounts of water ice at Mars' circumpolar regions early in 2002, first at the southern pole and later the northern as the carbon dioxide seasonal ice layer evaporated.
"I am very excited about landing in the ice-rich region we discovered with the GRS," Boynton said. "We think the ice in this region might have been deposited in the form of snow in the recent past when Mars was a lot wetter than it is now. The Phoenix mission should help us understand exactly how the ice was deposited in the polar regions."
Boynton heads one of the major science instruments on Phoenix, the thermal evolved gas analyzer (TEGA).
"Being a part of the Mars Polar Lander mission was a tremendous experience, but also an equally large disappointment when it crashed," Boynton said. His team initially designed, developed and built TEGA for the Mars Polar Lander. "It is great to get a second chance to actually land on the surface and dig down to where the interesting action might be beneath the surface."
The GRS on Mars Odyssey was a reflight of a similar instrument that was on another mission that failed, Mars Observer, in 1993. Results from the second chance to fly the GRS "were far more spectacular than anyone would have imagined," Boynton said. "I am hopeful that this second chance to fly the TEGA instruments will similarly provide us with many exciting discoveries that we cannot even contemplate now."
Using Earth as an analogy, previous successful missions to Mars landed at about the latitude of Mexico City (Viking 1 and Mars Pathfinder) or Chicago (Viking 2). The Phoenix lander targets the northern plains higher than 65 degrees latitude, the latitude of northern Greenland. The proposed landing longitude is around 240 degrees east, where Boynton's GRS detected nearly as strong a signature of water ice as at the exposed arctic ice cap.
Search for water history, habitat suitable for life
"Analyzing volatiles locked in arctic soils and the water chemistry of wet soils, even at one location, is a giant step toward modeling the weather processes and climate history of Mars," Smith said. 'Volatiles' include water, carbonates (limestone), organic material, and other substances that readily vaporize at temperatures up to 950 degrees Celsius.
And although only a decade ago scientists who confessed they wanted to search for life on Mars were apt to be censured, recent discoveries have made the hunt respectable.
"The biggest questions about Mars have to do with life," Smith said. "Is there life on Mars, has there ever been life on Mars, and if there is or was, how does it compare to life on Earth?"
"Microbial colonies can remain dormant for eons, yet survive. Recent work shows that dormant microbes are activated when water ice melts onto soil crystals at temperatures as cold as minus 20 degrees Celsius," he added.
The Phoenix robotic arm will scoop up martian soil samples and deliver them for heating into TEGA's tiny ovens so team members can measure how much water vapor and carbon dioxide gas are given off, how much water ice the samples contain, and what minerals are present that may have formed during a wetter, warmer past climate. TEGA will also measure any organic volatiles.
Using another instrument, MECA, researchers will examine soil particles as small as 16 microns across. They will measure electrical and thermal conductivity of soil particles using a probe on the robotic arm scoop. One of the most interesting experiments is the wet chemistry laboratory, Smith said.
"We plan to scoop up some soil, put it in a cell, add water, shake it up, and measure the impurities dissolved in the water that have leached out from the soil. This is important, because if the soil ever gets wet, we'll know if microbes could survive. We'll know if the wet soil is super acidic or alkaline and salty, or full of oxidants that can destroy life. We'll test the environment that microbes might have had to live and grow in," Smith said.
Smith and co-investigators
Smith was principal investigator for the successful Imager for Mars Pathfinder, which took 16,600 images from the surface of Mars during 83 days in 1997. As a member of the Mars Exploration Rover (MER) science team, he will help operate two rovers on the surface of Mars early next year. Smith is also part of Britain's Beagle2 project on the Mars Express mission launched last June. He is the project manager and a co-investigator for UA planetary scientist Alfred McEwen's HiRISE high resolution imaging system that will orbit Mars starting in 2006. He also is co-investigator on UA planetary scientist Martin Tomasko's DISR, a descent imager on the Cassini-Huygens mission that will parachute a probe into the dense atmosphere of Titan in January 2005.
Co-investigators include:
I'll have to show the Mars stuff to our youngest son. He's going to coach a Lego Robotics team this year and the theme is "Mars Explorer".
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.