Older Space Missions Still Making Headlines
As we speak, the future of manned exploration of the moon and Mars is being debated in light of the financial and technical challenges of such endeavors. While these debates go on, some of our aging space missions continue to come up with unusual discoveries and spectacular pictures of our universe. Take our two rovers that landed on Mars back in January 2004. Slated for tasks lasting only three months, over five years later both Spirit and Opportunity are still perking along. Well, Spirit isn't exactly perking along; it's been stuck in the same spot in loose sand since at least last April.
However, Opportunity has been traveling along on its way from Victoria Crater to the larger Endeavour Crater, a trip it started a year ago. Opportunity isn't known for speed. It has only covered about a fifth of the 12-mile distance between the two craters in that year. Now its journey has been delayed. A few weeks ago, some recent images taken along the way were relayed back to Earth and whoa! Opportunity had passed some 600 feet past a bluish tinted scraggly looking rock that was about 2 feet long and about a foot high and didn't look like the other rocks in the area. So, Opportunity was told to go back and touch the rock, named Block Island by the NASA/JPL team.
As the researchers thought, this rock turned out to be a meteorite, of the nickel-iron type. Opportunity's arm that touched the rock has an X-ray spectrometer, which can analyze for the elements comprising such a rock. The camera/microscope on the arm also revealed triangular surface features commonly found on nickel-iron meteorites found here on Earth. Such triangular patterns normally show up on surfaces of meteorites that have been etched in acid or occasionally in meteorites that have been eroded by sand blowing in winds on desert locations.
At roughly half a ton, Block Island is about ten times bigger than another meteorite found on Mars and the researchers believe that for such a large meteorite to have survived intact there had to be a significantly thicker atmosphere than currently exists on Mars. A thicker atmosphere would have served to slow down the falling meteorite. This brings up the possibility that the meteorite fell on Mars billions of years ago or, alternatively, that Mars has more recently been warm enough that large amounts of frozen carbon dioxide was released into the atmosphere in quantities sufficient to brake the falling meteorite.
When Opportunity finishes its work on Block Island, it's off again to Endeavour Crater. Meanwhile, what about Opportunity's stuck-in-place twin rover, Spirit? Please excuse me while I visit the NASA Web site for the latest on Spirit. ........ I'm back. Well, although Spirit hasn't been doing any traveling, it has been busy grinding down and studying the material of its surroundings and NASA still has hopes that it can spring Spirit free to move about on Mars once again.
As has often been the case with these columns, I start off writing about a particular topic or theme and find myself switching gears in midstream. When I went to the NASA site to check on Rover, there was "breaking news" of major significance that I'm sure will make or perhaps has already made headlines in the media. In a release on the Web site by Bill Steigerwald of NASA Goddard Space flight Center dated August 17, NASA headlines "NASA Researchers Make First Discovery of Life's Building Block in Comet"!
In an earlier column (1/10/2007), we talked about Stardust, a mission launched back in January 2004. The objective was to travel to the vicinity of the comet Wild 2 and bring home samples of the dust surrounding the comet. Stardust succeeded in trapping minute samples in an aerogel. The aerogel is a wispy sponge-like material that is about 99 percent empty space. The samples were returned to Earth in a capsule that parachuted down two years later in January 2006.
It's taken researchers the years since obtaining the samples to figure out how to reliably analyze such small samples, avoiding contamination back here on Earth. Now the scientists reveal that they have found glycine in these samples from the comet. Why the excitement? Glycine is an amino acid, one of twenty amino acids that serve as building blocks to make proteins, millions of them. Proteins (hemoglobin and enzymes, just to name a couple) are indeed the stuff of life and amino acids are the stuff of proteins. It's putting together amino acids in various combinations and shapes and sizes that builds the proteins involved in us humans and other forms of life.
But can we be sure that the glycine found in the Stardust samples isn't just contamination from handling the minute samples here on Earth? This, of course, was a prime concern for the investigators and they seem to have done an admirable job of ruling out contamination by analysis of isotopes. The "normal" (most abundant) form of carbon is carbon 12. Its nucleus has 6 protons and 6 neutrons. You probably have heard of carbon 14 dating, the dating of samples by measuring the amount of the isotope carbon 14, which has 8 neutrons and 6 protons. But there's another isotope, carbon 13, with 7 neutrons and 6 protons.
I don't know why, but the relative amount of carbon 13 in carbon in space is higher than the relative amount of carbon 13 in carbon here on Earth. Sure enough, when the researchers looked at the isotope composition of the glycine from Stardust, there was more carbon 13 than in glycine here on Earth. This was the key point of a paper presented by Jamie Elsila, Daniel Glavin and Jason Dworkin last Sunday, August 16, at a meeting of the American Chemical Society in Washington D.C.
So, why does Stardust Principal Investigator James Brownlee call these results "very exciting and profound"? The answer, obviously, lies in the fact that there are building blocks of life out there in comets. When a comet strikes Earth, as many have in the past, chances are that some of these amino acids will survive and hang around to form proteins. If you've got proteins, given the right conditions, you form some kind of life. Projecting out a bit, I would expect there are comets in other solar systems and it would be surprising if some of these comets did not have amino acids associated with them. If they meet up with an Earth-like planet in the right environment, could life be far behind?
What are the chances of finding one of these Earth-like planets? They've just gotten significantly better. The Kepler space telescope was launched in March of this year with a specific goal of finding not only Earth-size planets but Earth-like planets in orbit in habitable zones. In the August 7 issue of Science, William Borucki and over 20 other authors report on observations made on a decidedly unEarth-like planet, HAT-P-7b. I also found a report on these observations in a report on the NASA Web site dated August 6. HAT-P-7b is termed a "hot Jupiter" with a day-side temperature of over 4,000 degrees Fahrenheit and is so close to its sun that it orbits in only 2.2 days, a very short "year"!
You might well question why the measurements on such an unEarthly type planet bodes well for Kepler finding real Earth-like planets. The answer lies in the remarkable precision of the measurements, especially since the data were taken before the final calibrations and software fine tuning. Kepler was able to observe the heat generated by the hot planet and the effects due to the different phases of the planet, similar to the different phases of our moon. I was also impressed that the Science paper mentioned they had 10 days worth of photometric data on over 52,000 stars taken during the commissioning phase of the mission. I understand why the investigators are optimistic about what Kepler will accomplish when it's really up to speed.
Finally, I've been talking about the achievements of NASA's space missions; however, back in April the European Space Agency weighed with the launch of the largest space telescope to date. The Hershel Space Observatory has a mirror diameter of 3.5 meters, over 10 feet. By comparison, NASA's Spitzer Space Telescope's mirror is four times smaller in diameter. The July 31 issue of Science has a report by Michael Rowan-Robinson on Herschel with an impressive picture of the Messier 53 whirlpool galaxy taken in the infrared at various wavelengths. As with Kepler, this picture was taken before all the bells and whistles were in order and bodes well for the future.
Herschel's main goal is to look at the universe in infrared wavelengths that bridge the gaps between the wavelength capabilities of previous telescopes. Herschel will look at some of the coldest and most distant objects in the universe and it is projected to reveal much about the formation of galaxies and the chemical composition of the universe. A big advantage of looking out into space in the infrared is that infrared radiation can pass through cosmic dust, allowing you to see what goes on, for example, in the middle of our own Milky Way galaxy.
In order to work at the longer wavelengths of the infrared, the detectors have to be cooled to temperatures approaching Absolute Zero and infrared telescopes are launched with a sizeable quantity of liquid helium as coolant. Spitzer ran out of helium in May and is now limited to the shorter wavelengths more suitable for survey work. Herschel, on the other hand, is loaded for bear with 2400 liters of liquid helium and over half of observing time on Herschel for the next three years is already scheduled.
All this coolness contrasts with our recent weather here in New Jersey. After an unusually cool summer until very recently, we're having a heat wave and I've opted out of playing golf two weeks in a row because of the heat. You may have read or heard of our unusual weather this summer. This past Tuesday night, for example, we had a very brief minor thunderstorm. Only about 20 miles away, in Central Park in New York, hundreds of trees were down after a very brief, but obviously much more violent, thunderstorm. Could it be due to global warming? We'll never know.
Next column to be posted on September 3.
Allen F. Bortrum