I was recently introduced to A Time To Talk by Robert Frost. I like this thought about the importance of priorities and friendships.
When a friend calls to me from the road
And slows his horse to a meaning walk,
I don’t stand still and look around
On all the hills I haven’t hoed,
And shout from where I am, What is it?
No, not as there is a time to talk.
I thrust my hoe in the mellow ground,
Blade-end up and five feet tall,
And plod: I go up to the stone wall
For a friendly visit.
Tuesday, April 26, 2016
Friday, April 22, 2016
A new space drive?
It would be really cool if this were true. The Curious Link Between the Fly-By Anomaly and the “Impossible” EmDrive Thruster:
About 10 years ago, a little-known aerospace engineer called Roger Shawyer made an extraordinary claim. Take a truncated cone, he said, bounce microwaves back and forth inside it and the result will be a thrust toward the narrow end of the cone. Voila … a revolutionary thruster capable of sending spacecraft to the planets and beyond. Shawyer called it the EmDrive.
Shawyer’s announcement was hugely controversial. The system converts one type of energy into kinetic energy, and there are plenty of other systems that do something similar. In that respect it is unremarkable.
The conceptual problems arise with momentum. The system’s total momentum increases as it begins to move. But where does this momentum come from? Shawyer had no convincing explanation, and critics said this was an obvious violation of the law of conservation of momentum.
Shawyer countered with experimental results showing the device worked as he claimed. But his critics were unimpressed. The EmDrive, they said, was equivalent to generating a thrust by standing inside a box and pushing on the sides. In other words, it was snake oil.
Since then, something interesting has happened. Various teams around the world have begun to build their own versions of the EmDrive and put them through their paces. And to everyone’s surprise, they’ve begun to reproduce Shawyer’s results. The EmDrive, it seems, really does produce thrust.
An update: Some German researches say the drive could get us to the moon in four hours!
About 10 years ago, a little-known aerospace engineer called Roger Shawyer made an extraordinary claim. Take a truncated cone, he said, bounce microwaves back and forth inside it and the result will be a thrust toward the narrow end of the cone. Voila … a revolutionary thruster capable of sending spacecraft to the planets and beyond. Shawyer called it the EmDrive.
Shawyer’s announcement was hugely controversial. The system converts one type of energy into kinetic energy, and there are plenty of other systems that do something similar. In that respect it is unremarkable.
The conceptual problems arise with momentum. The system’s total momentum increases as it begins to move. But where does this momentum come from? Shawyer had no convincing explanation, and critics said this was an obvious violation of the law of conservation of momentum.
Shawyer countered with experimental results showing the device worked as he claimed. But his critics were unimpressed. The EmDrive, they said, was equivalent to generating a thrust by standing inside a box and pushing on the sides. In other words, it was snake oil.
Since then, something interesting has happened. Various teams around the world have begun to build their own versions of the EmDrive and put them through their paces. And to everyone’s surprise, they’ve begun to reproduce Shawyer’s results. The EmDrive, it seems, really does produce thrust.
An update: Some German researches say the drive could get us to the moon in four hours!
Monday, April 11, 2016
Thursday, April 07, 2016
Space Access - The moon has moonquakes
I am at Space Access for the next couple days. I won't be blogging about it as much as I have in years past. One thing I learned today that I found interesting is that the Moon has moonquakes.
NASA reports:
There are at least four different kinds of moonquakes: (1) deep moonquakes about 700 km below the surface, probably caused by tides; (2) vibrations from the impact of meteorites; (3) thermal quakes caused by the expansion of the frigid crust when first illuminated by the morning sun after two weeks of deep-freeze lunar night; and (4) shallow moonquakes only 20 or 30 kilometers below the surface.
The first three were generally mild and harmless. Shallow moonquakes on the other hand were doozies. Between 1972 and 1977, the Apollo seismic network saw twenty-eight of them; a few "registered up to 5.5 on the Richter scale," says Neal. A magnitude 5 quake on Earth is energetic enough to move heavy furniture and crack plaster.
Furthermore, shallow moonquakes lasted a remarkably long time. Once they got going, all continued more than 10 minutes. "The moon was ringing like a bell," Neal says.
On Earth, vibrations from quakes usually die away in only half a minute. The reason has to do with chemical weathering, Neal explains: "Water weakens stone, expanding the structure of different minerals. When energy propagates across such a compressible structure, it acts like a foam sponge--it deadens the vibrations." Even the biggest earthquakes stop shaking in less than 2 minutes.
I find this mind boggling, quakes that go on for hours.
NASA reports:
There are at least four different kinds of moonquakes: (1) deep moonquakes about 700 km below the surface, probably caused by tides; (2) vibrations from the impact of meteorites; (3) thermal quakes caused by the expansion of the frigid crust when first illuminated by the morning sun after two weeks of deep-freeze lunar night; and (4) shallow moonquakes only 20 or 30 kilometers below the surface.
The first three were generally mild and harmless. Shallow moonquakes on the other hand were doozies. Between 1972 and 1977, the Apollo seismic network saw twenty-eight of them; a few "registered up to 5.5 on the Richter scale," says Neal. A magnitude 5 quake on Earth is energetic enough to move heavy furniture and crack plaster.
Furthermore, shallow moonquakes lasted a remarkably long time. Once they got going, all continued more than 10 minutes. "The moon was ringing like a bell," Neal says.
On Earth, vibrations from quakes usually die away in only half a minute. The reason has to do with chemical weathering, Neal explains: "Water weakens stone, expanding the structure of different minerals. When energy propagates across such a compressible structure, it acts like a foam sponge--it deadens the vibrations." Even the biggest earthquakes stop shaking in less than 2 minutes.
I find this mind boggling, quakes that go on for hours.
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