Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. ×

Comment Re:Rockets are too expensive (Score 5, Interesting) 238

And a space elevator, of course, would only cost about a Trillion, and there's this little problem of it hitting something (we'd have to make Earth Orbit absolutely pristine and keep it that way) and there's a problem with the kinetic energy if it falls down. Sort of like having many atom bombs go off.

Maybe someday. But right now making rockets as cheap as they can be is a better idea. It's only $200K to fuel up a Falcon 9. We don't get the whole thing back in working order yet, but that would be a lot easier than making a space elevator.

Comment No Dragon 2 Soft Landing Yet (Score 5, Informative) 238

Dragon 2 isn't built yet. The escape test was a boilerplate capsule more like a Dragon 1 than 2. Dragon 2 has not demonstrated a soft landing, because it's not built yet. That was the Falcon 9 first stage.

Also, you can't get Dragon 2 down to the Moon and back up on it's own. Not enough delta-V. You would need to have Dragon ride on top of something that can hold enough fuel. Like a larger version of the Apollo Service Module.

The Command/Service module was originally intended to land on the moon and return without the LEM, before NASA bought the LEM concept, and was overpowered for the mission it got. Dragon is larger and heavier, but a lunar landing one would probably look a lot like an Apollo Command and Service module, and legs.

And yeah, Orion: I'm Not on Board. Big expensive obsolete rocket with no mission that makes sense.

But good luck getting Elon Musk to focus on the practical and eminently desirable target of the Moon. He isn't interested. It's only Mars for Elon.

I try not to watch all of the Mars Colonial Transport speculation. Falcon 9 and Dragon are great, and they're here, and we could do so much with them.

Moon

How To Get Back To the Moon In 4 Years -- This Time To Stay (scientificamerican.com) 238

Scientific American describes "a way to get to the Moon and to stay there permanently...to begin this process immediately and to achieve moon landings in less than four years." It starts by abandoning NASA's expensive Space Launch System and Orion capsule, and spending the money saved on private-industry efforts like Elon Musk's SpaceX and Robert Bigelow's Bigelow Aerospace. schwit1 quotes their report: Musk's rockets -- the Falcon and the soon-to-be-launched Falcon Heavy -- are built to take off and land. So far their landing capabilities have been used to ease them down on earth. But the same technology, with a few tweaks, gives them the ability to land payloads on the surface of the Moon. Including humans. What's more, SpaceX's upcoming seven-passenger Dragon 2 capsule has already demonstrated its ability to gentle itself down to earth's surface. In other words, with a few modifications and equipment additions, Falcon rockets and Dragon capsules could be made Moon-ready...

Major segments of the space community want every future landing to add to a permanent infrastructure in the sky. And that's within our grasp thanks to Robert Bigelow... Since the spring of 2016, Bigelow, a real estate developer and founder of the Budget Suites of America hotel chain, has had an inflatable habitat acting as a spare room at the International Space Station 220 miles above your head and mine. And Bigelow's been developing something far more ambitious -- an inflatable Moon Base, that would use three of his 330-cubic-meter B330 modules.

The article calls Jeff Bezos's Blue Origin rockets "a wild car" which could also land passengers and cargo on the moon and suggests NASA would be better off funding things like lunar-surface refueling stations, lunar construction equipment, and "devices to turn lunar ice into rocket fuel, drinkable water, and breathable oxygen."

Comment Re:Heat (Score 1) 190

I would be more interested in this if it worked the other way, warming my house.

There are lots of designs for doing that. Look at any renewable energy bulletin board (such as fieldlines.com).

Common thread is:
  - Black (or otherwise visible light absorbing) target.
  - In an insulated box.
  - With a glass window (that does NOT have an infrared reflective coating)
  - And some way of transferring the heat from the black target to the house air.

Glass is opaque to infrared and passes visible light. Sunlight goes through, is absorbed by the black material, and heats it (to the tune of about a kilowatt per square meter at noon). The material re-radiates, but it is far too cool to re-radiate in the visible spectrum. So it re-radiates in the infrared, which doesn't escape through the glass and is thus re-absorbed.

It's called "The Greenhouse Effect". B-)

In one of my favorite designs the black target is a series of tubes consisting of used aluminum drink cans with the tops and bottoms removed, painted black. They're very good at absorbing light, because it takes multiple bounces down the valley between the tubes, giving the paint many chances to absorb it. A 4" computer fan pumps air through the box to extract the heat.

But there are LOTS of other designs. Including houses with large south or south-east facing windows and overhanging roofs that shade them in the summer but not in the winter (to rough-tune the absorption). The floor, walls, furniture, etc. serve as the visible light absorber.

My ranch house works like that - a little too well. In the afternoon it will git to 90+ degrees when it's single-digit temperatures outside.

Comment Re:Too good to be true. (Score 1) 190

It's a neat idea, but what happens in the winter?

Put a cover over it.

Glass is good. It is pretty much opaque to far infrared. Instead of seeing the cosmic background temperature of a few degrees kelvin, it will see the temperature of the glass - which is about the same as its own temperature. So the radiative heat flow will be just about zero.

But ANYTHING opaque to infrared will do the same.

Another approach: Instead of coating the house, coat a radiative cooler to make chill water, and pump that through a heat exchanger in your forced air heating/air conditioning system. Don't want cooling? Don't pump the water. (Adjust how much you pump it to regulate your temperature.)

That's not "no power", but pumping chill water is very little power, and you need to circulate the air anyhow. Most of the energy cost of air conditioning is refrigeration, and you still get that for free.

Comment RTFA. They DID try it on people. (Score 1) 154

RTFA. Then follow the link to the paper. They DID try it on humans. Worked reasonably well (though the sample was small so it was more "does this maybe work on people, too? Is it worth a big study to check?" rather than "do all the results reproduce in people just like mice or are they quantitatively different in THIS way?").

Interestingly, they used a proprietary commercial boxed Fasting Mimicing Diet - L-Nutra's ProLon (Developed by a team including a USC Davis professor specializing in gerontology and life-extension) - on the human experimental subjects.

Comment Re:I blame Trump. (Score 5, Insightful) 1028

Well, that's one way of looking at it. Another way is that black people do a lot more murder on a per capita basis. As it turns out, the chances of getting killed by a white guy are less for a black person than the reverse. Which is indicative of the overall murder rate in the black community being several times (something like 5+ times) what it is amongst whites.

Some source data

Anyway paying undue attention to a single person amongst the 6k or so that are going to die this year is politically motivated, as usual.

Comment Re:I blame Trump. (Score 2, Insightful) 1028

I agree with you. People say a lot of stupid things when they are drunk. But let's not let any opportunity to blame Trump go to waste, right?

And Leftists wonder why they are getting tuned out.

500 white people are killed by blacks every year and 200 blacks are killed by whites every year. One group is 70% of the country, the other is 13% of the country. I notice the same people whining about this event aren't paying attention to those statistics. A couple people assuredly died in interracial murders since that story broke.

But this one drunken fight in Kansas - we have no idea what was actually said and what provoked this - is somehow more significant.

Slashdot Top Deals

Nothing is more admirable than the fortitude with which millionaires tolerate the disadvantages of their wealth. -- Nero Wolfe

Working...