新部落
I think, therefore I am. - René Descartes
NASA 周五宣布，Phoenix Mars Lander
在火星上發現了水。這可以說是人類在宇宙探索方麵一個裏程碑式的重大發現。水是生命之源，有了水就有產生生命的可能。也許人類在將來某一天真的會發現被念叨了幾百年的火星人馬嬸（Martians)？！也未可知。
但僅是這個匪夷所思的想法就夠地球人折騰幾個世紀的了 - 對於詩人來說是增添了無盡的靈感；對於科普作家和好萊塢電影來說是取之不盡的創作源泉；而對於那些
space lovers 來說這個發現絕對是真正的福音啊。
興奮歸興奮。也許人類發現火星人的概率是微乎其微幾近於零，也許最後能夠發現的火星上最高級的生命形式充其量也不過隻是一些
bacteria 而已。但是，火星上有水這一事實，為人類開發火星的前景提供了更為具體的現實性，沒準將來人們去火星旅遊度假過周末都是有可能的事情。
自上一世紀以來地球表麵上東西南北各種走向的洲際移民潮，受政治動蕩，經濟消長的左右，三十年河東，三十年河西，誰也拿捏不準究竟那兒是最好的安身立命之地。地球愈演愈烈的升溫加熱變臉，把當年高貴的地球人兒弄得現如今真像是熱鍋上的螞蟻一般，更是為移民心理帶來了一個巨大的變數。由此想開去，沒準將來火星會成為全太陽係最佳移民選擇。月球雖是富有浪漫氣息的地球近鄰，被古人奉為“月宮”，但那兒太冷，美麗凍人，更要命的是沒有水（至少到現在還沒有充分證明這一點）！！！火星雖然顏色單調了一點，但最主要的是有水呀。水是生命之本，難怪我們地球人常說“女人是水做的”，真是千古不變的宇宙定律：到了火星上，男女都必須是水做的，否則就真的看起來幹巴巴像是長期缺水的馬嬸（Martians）一樣了。
火星上的地球移民人人手持一本火星永久居住證，既然火星是紅色的，那就應該是“紅卡”，比地球上那些綠卡黑卡以及其它各種不同顏色的卡們可神氣多了。紅卡在手，火星居民們都暗自慶幸自己從“熱鍋上的螞蟻”搖身一變升華到先進的火星移民行列。在這片紅色的土地上，愛球主義是紅色星球居民的基本信念，在恒溫條件下保持全球一片紅是他們的基本球策，火星移民的最終目標是建立起一個隻有和諧沒有紛爭，不會像地球那樣翻臉不認人的紅色極樂世界。
當然，時間久了，那些移民火星的人們也許偶爾會緬懷一下在地球上度過的那些美好時光，略帶傷感的懷念地球美麗的蔚藍色，甚至有幾位可能會想起當年工作之餘在文學城看完八卦消息然後奮筆疾書寫博客的那些消停日子。。。。。人生啊，人生！:-))
扯遠了！
無論如何，火星上水的發現這一事實，進一步激發了人類探索宇宙其它生命形式的熱情與想像力。水的發現讓紅色的火星和藍色的地球之間的人文距離給一下子拉近了！
Water discovery on Mars drives search for life
Phoenix Mars Lander will now analyze water in search of organic material
By Andrea Thompson Aug. 1, 2008
NASA's Phoenix Mars Lander may have found
water ice on the red planet, but it still has a lot of work left to do to answer
the question that has been on scientists' minds for decades: Has Mars ever been
capable of harboring life?
Phoenix scientists announced yesterday that the mission finally confirmed the
presence of subsurface water ice in the north polar regions of Mars — first
detected by NASA's Mars Odyssey orbiter in 2002 — about two months after
touching down on the Martian surface on May 25.
The lander is now analyzing the ice to see if it was ever a liquid and if it
contains organic materials, the building blocks of life.
The ice, collected from below the surface at the lander's site in the Martian
arctic, could have acted like a freezer, protecting any organics that may have
formed there.
"We have an environment where organics could be preserved," said mission
scientist William Boynton of the University of Arizona.
The detection of organics on Mars would not necessarily mean there is life. It
would just mean that carbon and other molecules that make up life as we know it
were present.
"Organics would be the home run or the grand slam of the mission," said Bruce
Jakosky, a geologist at the University of Colorado who is not affiliated with
the mission. However, if they don't find organics, "that doesn't mean that there
wasn't life on Mars," Jakosky said. Other missions, planned and unplanned, will
keep the search alive.
Liquid water
The confirmation of the Odyssey ice observations was a key goal of the $420
million Phoenix mission, but only the first of several steps in characterizing
the dirt and ice layer of Mars' Vastitas Borealis region to determine whether it
may once have been habitable at some point in the planet's past.
'I see this as a step along the way of Phoenix getting to its major science
results," Jakosky said. "By itself, that's not a major result."
One of those steps is determining whether the water ice ever existed in a liquid
form, said Phoenix robotic arm co-investigator Ray Arvidson of Washington
University in St. Louis — liquid water being a key resource for life as we know
it.
Phoenix will look for signs of ancient liquid water by heating up samples of the
icy dirt mixture in the tiny ovens of its Thermal and Evolved-Gas Analyzer (TEGA),
which can analyze the vapors given off by the heated samples to analyze their
composition.
TEGA has already begun heating up the sample that confirmed that the rock-hard
layer beneath the surface dirt was indeed water ice — when ice begins to melt,
it takes more heat to raise the temperature of the sample. Over the course of
the next week, TEGA will gradually heat the sample all the way up to 1,832
degrees Fahrenheit (1,000 degrees Celsius).
As the sample is heated, any hydrated minerals, or those that likely formed in
the presence of liquid water, show themselves as they break apart and the
signature of their water is detected by the instrument, explained Boynton, a
TEGA co-investigator.
Finding hydrated minerals, such as carbonates, sulfates or clays, would indicate
that liquid water once permeated the Martian regolith where Phoenix now sits,
Arvidson said in a telephone interview last night.
This water would not have flowed as rivers or streams, as it once likely did
closer to Mars' equator, where hydrated salts have already been found by NASA
orbiters and rovers, but would have percolated through the dirt layer as Mars'
orbital motions tipped the northern parts of the planet toward the sun, warming
them up, Arvidson added.
The stuff of life
The other big signature Phoenix will look for as the mission continues and the
probe's ovens heat up dirt samples will be organic molecules, the building
blocks of life.
"Finding organics would really change our way of thinking," Boynton said.
But so far, organic molecules haven't shown up on Mars. When the Viking landers
heated up dirt samples in the 1970s, "there were really no organic molecules at
all," Boynton said.
But dirt near the Martian equator faces strong oxidizing pressures, which can
destroy organics, Boynton added, which is why Phoenix is looking for them
farther north.
Organics have proven elusive to Phoenix so far; the first dirt sample analyzed
by TEGA, taken from the surface, found no sign of them. But this wasn't much of
a surprise to mission scientists.
"We didn't really expect to find them in the surface soils," because the surface
is subjected to the same oxidizing pressure as the equatorial regions, Boynton
told SPACE.com.
TEGA will keep looking for signs of organics in subsequent samples taken closer
to the ice layer, he added.
If Phoenix doesn't find organics, the mission won't be a flop, Jakosky said,
because it still gives scientists valuable information about the northern
region. "Whatever they find is exciting," he said.
If it does detect organics though, mission scientists will be cautious about
interpreting the findings, Boynton said. They would assume first that any
organics could be contamination brought with the spacecraft from Earth. Mission
scientists will check with a "blank" brought from Earth to determine whether or
not any organics discovered are terrestrial stowaways.
Even if the blank shows that the organics came from the Martian soil, they still
may not be native, Boynton said, since the same organic-bearing meteorites that
strike Earth strike Mars as well. Determining the ultimate origin of any
organics would likely take bringing back a sample to Earth, a project that both
NASA and the European Space Agency are working toward.
And organics don't on their own equal life. "Just because there are organic
compounds, doesn't mean that that's life," said Kim Seelos, a postdoctoral
researcher at Johns Hopkins University.
Future missions
Whether or not Phoenix finds signs of organics, it won't be the last time that
NASA looks for them on Mars. NASA's Mars Science Laboratory (MSL), set to launch
in 2009, will pick up where the 1970s Viking missions left off, exploring the
regions closer to the equator for signs of them.
MSL will be better equipped than Viking, and even Phoenix, to detect organics in
dirt samples, with more powerful and sensitive equipment, as well as the ability
to roam around.
While "life is teeming on Earth," Arvidson said, it may not have been so dense
on Mars — if it ever existed — perhaps only forming in small pockets. Since
Phoenix, as a lander, stays put by definition, it can only explore the patch of
ground in its immediate vicinity.
However, any organics detected by MSL would have formed in a much more ancient
period of Mars' history because the landscape near Mars' equator formed billions
of years ago. The surface that Phoenix is exploring is much younger, only tens
of millions of years old.
For now, Phoenix is the only chance of finding organics on this region of Mars,
since no future missions in the works now are planned to return to the frozen
northern reaches. To get another mission back there to look the region in
greater detail, "it would probably take finding organics," Boynton said.
But "Phoenix isn't the last gasp, or MSL isn't the last gasp" to answering the
question of whether life ever existed on Mars, Jakosky said.
The evidence available to scientists now suggests that Mars could have harbored
life, it's just a matter of finding a spot that preserves the signs of it, he
added. And Phoenix's landing site, or even MSL's, may not be the ideal spot to
go and look for those signs, whether by sending another rover or staging a
mission to return a sample to Earth.
There are plenty of other environments on Mars where Jakosky would like to look
for signs of life. While he can't point to a particular spot, there is evidence
that Mars once had features that could have supported life, including ancient
lake beds, ancient highlands where evidence suggests that water existed for long
periods of time, and hot springs — "places like Yellowstone," as Jakosky
describes them.
Some scientists, such as Seelos, doubt that clear evidence of Martian life
itself will ever be found because any life would have likely been microbial,
which is not easily preserved as fossils. But Jakosky sees this as an
"unnecessarily pessimistic" view, because ancient microbes have been preserved
in some places on Earth.
But it could be awhile before scientists ever answer the question of life on
Earth because they currently understand so little about the history and geology
of Mars, Jakosky said.
"We don't know the answer and I don't even know how to put odds on "when and
whether they will find the answer," Jakosky said.
His advice is to keep using missions like Phoenix, MSL, and eventually a sample
return mission to build our knowledge of Mars, as we have built the knowledge of
our own planet's past.
© 2007 Space.com. All rights reserved. More from Space.com.
還在火星上探寶麽 :))
中秋節愉快！
More than likely, the result of human's quest for Martians is nothing more than a bounch of becteria. :-))