NASA has extended the missions of the rovers on Mars, Spirit and Opportunity, for a fifth time. The two have been roving since January, 2004, and this extension will take the mission into 2009. For missions scheduled to last only 90 days each, the rovers have been incredibly successful. Together, they have beamed back nearly 200,000 images, plus other streams of scientific data. The Rovers of Mars will always have a chapter in any history of early space exploration.
All that said, however, they also tell us about the limitations of robotic exploration. In 45 months, Opportunity has traveled a bit over 7 miles, while Spirit has made about 4.5 miles. A well-equipped human mission-- the only kind worth sending-- could cover that much ground the first day, and curious, educated human scientists on the spot could explore with more insight and efficiency. It's true, more advanced robots could do better than Spirit and Opportunity, but the biggest need is for artificial intelligence,, to allow the robot to act on its own, and developing AI has proven much more difficult than scientists originally believed. Progress is being made, but AI capable of tackling Mars might have to wait for the second half of this century.
So, if we want to study Mars but don't really care how long it takes to get the answers we seek, a continued robot program would be sufficient. If, on the other hand, we want to understand Mars and know whether there has ever been Martian life and leave exciting options to our children, mounting a program to send human explorers is essential.
Tuesday, October 16, 2007
Monday, October 15, 2007
Health on Luna
Many space advocates see the establishment of lunar bases as the first steps towards full-fledged lunar settlements, much as cities in the American West grew up around Army forts, tradiing posts, harbors, and railroad routes. It's an attractive argument to many, but it ignores at least one fundamental factor. People in nineteenth century America knew humans could survive in the plains, mountains, and deserts of the West. Today, it's not yet clear humans can live indefinitely on the Moon.
Radiation and the effect of low gravity on the human body over an extended period seem to pose the biggest health concerns. As we get into such a project, however, we may well find other negative factors. Building habitats in free space and controlling every aspect of the environment-- including radiation levels and the strength of gravity-- may be the only way humans can live lifetimes beyond Earth.
On the other hand, blocking radiation from reaching lunar settlement areas in thoroughly possible, and low gravity has its benefits. Falling on Luna, for example, would be a much slower affair. Most people could easily catch themselves. In any case, landing would not be the thump it is on Earth. Stress on the heart on Earth comes from requiring the heart to constantly, rhythmically push blood from the feet up against the pull of Earth's gravity. Lunar gravity is only one-sixth as strong. All else being equal, therefore, a human heart could last many times as long on Luna as it does on Earth. Throw in advanced medical care and a calm, functioning, fulfilling society and Lumans might enjoy absolutely Old Testament lifespans.
Radiation and the effect of low gravity on the human body over an extended period seem to pose the biggest health concerns. As we get into such a project, however, we may well find other negative factors. Building habitats in free space and controlling every aspect of the environment-- including radiation levels and the strength of gravity-- may be the only way humans can live lifetimes beyond Earth.
On the other hand, blocking radiation from reaching lunar settlement areas in thoroughly possible, and low gravity has its benefits. Falling on Luna, for example, would be a much slower affair. Most people could easily catch themselves. In any case, landing would not be the thump it is on Earth. Stress on the heart on Earth comes from requiring the heart to constantly, rhythmically push blood from the feet up against the pull of Earth's gravity. Lunar gravity is only one-sixth as strong. All else being equal, therefore, a human heart could last many times as long on Luna as it does on Earth. Throw in advanced medical care and a calm, functioning, fulfilling society and Lumans might enjoy absolutely Old Testament lifespans.
Sunday, October 14, 2007
Dawn's Ion Engines
NASA's Dawn mission to the asteroid belt passed a test of its clustered ion engines this month, paving the way for the flight to Vesta, Ceres, and beyond.
Ion propulsion is one technology NASA believes may really open up the Solar System. The Dawn mission, therefore, is about science, but it's also about technology demonstration. The spacecraft's engines will operate continuously for five years. Ion engines produce very little thrust, but they can do so for enormously long periods of time, slowly building up great speed.
The eventual role of ion drives may encompass more than robotic spacecraft.. Ion propulsion might be ideal for unmanned ships transporting cargo throughout the Solar System, helping to establish an economy beyond Earth. Possibly, it could drive early Martian exploration and settlement. The ultimate value of ion drive, however, could lie in the opening of the outer Solar System. The vast distances involved may fit ion's steady build to enormous speed perfectly.
Ion propulsion is one technology NASA believes may really open up the Solar System. The Dawn mission, therefore, is about science, but it's also about technology demonstration. The spacecraft's engines will operate continuously for five years. Ion engines produce very little thrust, but they can do so for enormously long periods of time, slowly building up great speed.
The eventual role of ion drives may encompass more than robotic spacecraft.. Ion propulsion might be ideal for unmanned ships transporting cargo throughout the Solar System, helping to establish an economy beyond Earth. Possibly, it could drive early Martian exploration and settlement. The ultimate value of ion drive, however, could lie in the opening of the outer Solar System. The vast distances involved may fit ion's steady build to enormous speed perfectly.
Friday, October 12, 2007
Pluto's Family
Astronomers using the Keck telescope in Hawaii have taken the best photos yet of the Plutonian system. They hope to increase our basic kbowledge of Pluto and its three moons before the arrival next decade of the New Horizons probe.
For such a small body moving so slowly so far into the depths of the Solar System, Pluto has quite a bit going on around it. Charon, its largest moon, is roughly half the size of Pluto itself. We used to say Charon was the largest moon relative to its planet in the Solar System, but Pluto is no longer officially a planet. The largest moon relative to its planet now reverts back to Earth's Luna. Conspiracy? Anyway, Pluto also has two tiny moons, Nix and Hydra. Astronomers hope to get enough high quality images to pin down the smaller moons' orbits and masses.
The two small moons of Mars are thought to be captured asteroids. Mars orbits on the inner edge of the Main Belt of asteroids, so such captures seem plausible. It's likely fair to say Pluto orbits on the inner edge of the Kuiper Belt, but such a comparison is probably misleading. The outer Solar System is a vast realm, and Pluto is a featherweight; Pluto and Charon combined probably don't come to even half the mass of Mars. How Pluto could have captured two small bodies while bigger Mars captured the same number in a busier neighborhood seems to ask for an explanation. Part of that explanation likely is that bodies move more slowly in Pluto's neighborhood, and so would be more easily captured. Lack of speed coupled with the area involved, of course, also suggests close approaches that might allow captures would the extremeky rare.
The histories of Nix and Hydra might be quite interesting.
For such a small body moving so slowly so far into the depths of the Solar System, Pluto has quite a bit going on around it. Charon, its largest moon, is roughly half the size of Pluto itself. We used to say Charon was the largest moon relative to its planet in the Solar System, but Pluto is no longer officially a planet. The largest moon relative to its planet now reverts back to Earth's Luna. Conspiracy? Anyway, Pluto also has two tiny moons, Nix and Hydra. Astronomers hope to get enough high quality images to pin down the smaller moons' orbits and masses.
The two small moons of Mars are thought to be captured asteroids. Mars orbits on the inner edge of the Main Belt of asteroids, so such captures seem plausible. It's likely fair to say Pluto orbits on the inner edge of the Kuiper Belt, but such a comparison is probably misleading. The outer Solar System is a vast realm, and Pluto is a featherweight; Pluto and Charon combined probably don't come to even half the mass of Mars. How Pluto could have captured two small bodies while bigger Mars captured the same number in a busier neighborhood seems to ask for an explanation. Part of that explanation likely is that bodies move more slowly in Pluto's neighborhood, and so would be more easily captured. Lack of speed coupled with the area involved, of course, also suggests close approaches that might allow captures would the extremeky rare.
The histories of Nix and Hydra might be quite interesting.
Thursday, October 11, 2007
Opening Day for ATA
Today, the Allen Telescope Array will see first light-- err, hear first radio crackle-- as Paul Allen, cofounder of Microsoft and major financial force behind the ATA, will push the button that brings the first 42 radio telescopes online. The ATA will be the key tool in the largest SETI research program yet undertaken.
The 42 telescopes Allen will activate are only the first installment of an array that will finally contain 350 individual instruments. The real power of the installation, though, is not the number of individual telescopes. Rather, it's the fact that those telescopes will be used together to essentially create one huge radio telescope. Though constructed to take SETI research to the next level, the ATA will also be capable of groundbreaking work in radio astronomy.
Located 300 miles northeast of San Francisco in California's Hat Creek Valley, the Array is being built in a remote, mountainous area where the radio sky is fairly quiet. Dr, Seth Shostak of the SETI Institute has speculated we could well find our first radio signal from an alien civilization by 2025. Starting today, the chances of that happening are increasing.
The 42 telescopes Allen will activate are only the first installment of an array that will finally contain 350 individual instruments. The real power of the installation, though, is not the number of individual telescopes. Rather, it's the fact that those telescopes will be used together to essentially create one huge radio telescope. Though constructed to take SETI research to the next level, the ATA will also be capable of groundbreaking work in radio astronomy.
Located 300 miles northeast of San Francisco in California's Hat Creek Valley, the Array is being built in a remote, mountainous area where the radio sky is fairly quiet. Dr, Seth Shostak of the SETI Institute has speculated we could well find our first radio signal from an alien civilization by 2025. Starting today, the chances of that happening are increasing.
Wednesday, October 10, 2007
Enceladus Has Geysers
As reported earlier in this blog, scientists working on the Cassini mission to Saturn and its environs discovered eruptions from the moon Enceladus, Now, the team led by Carolyn Porco has determined the eruptions come from geysers.
The geysers are in the area of the south pole, and the ejecta from the geysers account for the so-called "tiger stripes" on the surface. The ejecta also seems to feed the E-ring, a tenuous ring surrounding Saturn.
The geysers are likely driven by friction within Enceladus caused by the gravity of Saturn as it pulls on the body of the moon. Scientists also believe there is a huge ocean of water underneath the surface of Enceladus. With water, with energy, and possibly with organic compounds, the possibility of life exists.
The geysers are in the area of the south pole, and the ejecta from the geysers account for the so-called "tiger stripes" on the surface. The ejecta also seems to feed the E-ring, a tenuous ring surrounding Saturn.
The geysers are likely driven by friction within Enceladus caused by the gravity of Saturn as it pulls on the body of the moon. Scientists also believe there is a huge ocean of water underneath the surface of Enceladus. With water, with energy, and possibly with organic compounds, the possibility of life exists.
Tuesday, October 9, 2007
Asteroid Bonanza
Sometimes you look for one thing, but find something else entirely. That's what happened to a team of five astronomy students from the University of Washington.
The team, working under the direction of assistant professor Andrew Becker, was looking for supernovae, but asteroids kept getting in the way Eventually, the team catalogued about 1,300 previously undiscovered asteroids. That's about 1 out of every 260 known objects in the Solar System.
Happily, none of the asteroids discovered pose an immediate danger to Earth, though some of them do cross Earth's orbit in their own orbits, and may, therefore, threaten Earth at some point.
The team, working under the direction of assistant professor Andrew Becker, was looking for supernovae, but asteroids kept getting in the way Eventually, the team catalogued about 1,300 previously undiscovered asteroids. That's about 1 out of every 260 known objects in the Solar System.
Happily, none of the asteroids discovered pose an immediate danger to Earth, though some of them do cross Earth's orbit in their own orbits, and may, therefore, threaten Earth at some point.
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