For decades, space advocates have touted solar power satellites as the ultimate solution to the world's energy needs. Such satellites would collect energy pouring out from the Sun and beam it down to Earth, where it would enter the planet's electric power grid. That energy, they argue, would be clean, essentially inexhaustible, and, at least over time, cheap.
The drawbacks for SPS have been a huge initial capital cost, and the equally huge size of the power satellites themselves. Now, NASA is backing a new technology project called SPS-ALPHA which seeks to deal with both cost and size. Instead of constructing a large structure in orbit-- several times larger than ISS-- SPS-ALPHA will study an approach that would use tens of thousands of small elements that would fly in a configuration that would allow them to do the same job as a large SPS. The concept is the same as using a network of several small telescopes to essentially create one huge telescope. By using the same component tens of thousands of times per power satellite, the theory is that by relying on components that could be mass produced, the cost of the overall actual project could be drastically reduced.
SPS-ALPHA is a one year concept study. The near-term goal of the study is to lay the groundwork for a test flight of the technology required in a few years.
Sunday, April 8, 2012
Friday, April 6, 2012
Plutonium-238
For decades, NASA has been using plutonium-238, an isotope of plutonium, to power spacecraft on extended, deep space missions. No, it's not a matter of nuclear reactions. Rather, plutonium-238 gives off heat, and that heat is used in radioisotope thermoelectric generators (RTGs) to turn that heat into power that runs the spacecraft, often over decades.
The problem is the United States stopped producing plutonium-238 in the 1980s, and now the supply of the stuff is running low, which puts future NASA exploration of the outer planets, for example, in jeopardy. The Department of Energy, however, is restarting production, and plans to have a usable supply by 2017.
Of course, because of federal government budget woes, NASA has cut way back on its outer planets exploration prograam, but if money ever flows back into that area, there should be enough plutonium-238 to power the probes all the way out.
The problem is the United States stopped producing plutonium-238 in the 1980s, and now the supply of the stuff is running low, which puts future NASA exploration of the outer planets, for example, in jeopardy. The Department of Energy, however, is restarting production, and plans to have a usable supply by 2017.
Of course, because of federal government budget woes, NASA has cut way back on its outer planets exploration prograam, but if money ever flows back into that area, there should be enough plutonium-238 to power the probes all the way out.
Thursday, April 5, 2012
Atlas 5
The United Launch Alliance is confident it can upgrade its Atlas 5 rocket to man-rated status in time to be operational and carrying astronauts to orbit by 2015, two years ahead of NASA's schedule.
The Atlas 5 will be the launcher of choice for the new manned spacecraft being developed by Boeing, the Sierra Nevada Corporation, and Blue Origin, though Blue Origin is also working on its own launcher. Of course, designing an upgrade so the Atlas 5 is compatible with three different manned vehicles is quite an engineering challenge, but ULA is comfortable it can do the job.
Since its first flight in 2002, the Atlas 5 has 28 successful launches without a failure, so its fundamental reliability is fairly well established. Man-rating it will require more powerful upper stage, but ULA already has that rocket in its stable. NASA and the American aerospace industry are eager to bring private sector vehicles online to end the monopoly in manned spaceflight currently enjoyed by the Russian Soyuz.
The Atlas 5 will be the launcher of choice for the new manned spacecraft being developed by Boeing, the Sierra Nevada Corporation, and Blue Origin, though Blue Origin is also working on its own launcher. Of course, designing an upgrade so the Atlas 5 is compatible with three different manned vehicles is quite an engineering challenge, but ULA is comfortable it can do the job.
Since its first flight in 2002, the Atlas 5 has 28 successful launches without a failure, so its fundamental reliability is fairly well established. Man-rating it will require more powerful upper stage, but ULA already has that rocket in its stable. NASA and the American aerospace industry are eager to bring private sector vehicles online to end the monopoly in manned spaceflight currently enjoyed by the Russian Soyuz.
Wednesday, April 4, 2012
Many Minimoons Of Earth
A new study using one of the longest, most complex computer simulations yet done suggests Earth often has more than one moon.
The study says that over the billions of years of Earth history, the planet's gravitational well-- the deepest in the inner Solar System, after all-- has captured many small asteroids and held them in orbit for months, years, or decades. Those orbits, however, have been highly elliptical, and the interplay of the interacting gravitational fields of Earth, the Moon, and the Sun eventually kick the minimoons out of Earth orbit and back into solar orbit.
Had such a minimoon been around the past few decades, it would have been a real boon for science, and obviously an early target in the Space Age. The possibility does suggest an interesting approach for the future. Instead of waiting for Earth to capture another one on its own, we could help things along by maneuvering a small body into such a temporary Earth orbit. That would extend our capabilities in space while giving us an asteroid to study at close range using the full resources of Earth's astronomical community. By setting up sophisticated science packages on the asteroid while it orbits Earth and waiting, we could eventually have a very good observatory in solar orbit.
The study says that over the billions of years of Earth history, the planet's gravitational well-- the deepest in the inner Solar System, after all-- has captured many small asteroids and held them in orbit for months, years, or decades. Those orbits, however, have been highly elliptical, and the interplay of the interacting gravitational fields of Earth, the Moon, and the Sun eventually kick the minimoons out of Earth orbit and back into solar orbit.
Had such a minimoon been around the past few decades, it would have been a real boon for science, and obviously an early target in the Space Age. The possibility does suggest an interesting approach for the future. Instead of waiting for Earth to capture another one on its own, we could help things along by maneuvering a small body into such a temporary Earth orbit. That would extend our capabilities in space while giving us an asteroid to study at close range using the full resources of Earth's astronomical community. By setting up sophisticated science packages on the asteroid while it orbits Earth and waiting, we could eventually have a very good observatory in solar orbit.
Tuesday, April 3, 2012
Closing In On Alien Life
Shawn Domagal-Goldman, a research exobiologist based at NASA Headquarters, predicts that we will find an "alien Earth"-- a world similar to Earth in size and composition, and orbiting within the habitable zone of its parent star-- by 2014. The prediction is based largely on the data being gathered by NASA's Kepler planet hunting spacecraft, which has already found thousands of candidate exoplanets. Candidates have to be confirmed before being officially recognized as worlds.
Seth Shostak of the SETI Institute is holding to a prediction he made that we will find a signal from an extraterrestrial civilization within the next twenty years. With the continued development of the Allen Telescope Array, SETI searches will become increasingly wide-ranging over that period, making Shostak's inkling more plausible.
Scientists generally are careful about making bold assertions. They don't want to end up looking stupid any more than anybody else does. So, when two scientists make such predictions, perhaps the rest of us should note that we may be getting close to answering in the negative the fundamental question: "Are we alone?"
Seth Shostak of the SETI Institute is holding to a prediction he made that we will find a signal from an extraterrestrial civilization within the next twenty years. With the continued development of the Allen Telescope Array, SETI searches will become increasingly wide-ranging over that period, making Shostak's inkling more plausible.
Scientists generally are careful about making bold assertions. They don't want to end up looking stupid any more than anybody else does. So, when two scientists make such predictions, perhaps the rest of us should note that we may be getting close to answering in the negative the fundamental question: "Are we alone?"
Monday, April 2, 2012
Space Coast Woes
Scott Pelley followed up his"60 Minutes" interview with SpaceX founder Elon Musk by looking at Florida's Space Coast in the wake of the retirement of the space shuttle. It wasn't a pretty picture. Businesses are failing, families are moving away, lives are being disrupted. That's the economic impact on Brevard county of ending the money flow of the shuttle program without replacing it with another program.
There's also an emotional component. Workers who built their careers, thirty years, in the shuttle program are now, too often, high and dry. Many of those people took immense, intense pride in doing a job for their country that no other group in the world could do. Many of those are struggling with that pride, trying to understand why their country abandoned the shuttle program, and with it a leadership role in space.
There's also an emotional component. Workers who built their careers, thirty years, in the shuttle program are now, too often, high and dry. Many of those people took immense, intense pride in doing a job for their country that no other group in the world could do. Many of those are struggling with that pride, trying to understand why their country abandoned the shuttle program, and with it a leadership role in space.
Sunday, April 1, 2012
Celestial Target Practice
In less than a week, three asteroids have zipped past Earth well within the orbit of the Moon, and a fourth is scheduled to fly past just outside lunar orbit April 4. Today, the asteroid 2012 EG5, 150 feet across, which was only discovered March 23, flew past at little more than half the distance to the Moon.
NASA assures us that none of those bodies pose a threat to Earth, but the sheer number of close shaves it continues to document should give policymakers around the world pause. The major question is whether a planetary defense program will be put into place before a disaster occurs, or after.
NASA assures us that none of those bodies pose a threat to Earth, but the sheer number of close shaves it continues to document should give policymakers around the world pause. The major question is whether a planetary defense program will be put into place before a disaster occurs, or after.
Subscribe to:
Posts (Atom)
