Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror
Compare cell phone plans using Wirefly's innovative plan comparison tool ×

Comment Re:Propellant or Hydraulic Fluid (Score 2) 71

It was only once that they ran out of hydraulic fluid, they fixed that the next flight. Sticky engine gimbal caused another crash. The engine pivots to help steer it for landing, but it was moving too slowly, so they landed at an angle instead of vertical. Finally, one time a landing leg failed to lock. So it landed vertical, but then fell over. They have been learning by crashing, and generally don't have the same problem twice. Since expendable rockets *always* crash, flight testing the landing system this way doesn't cost much extra.

Comment Re:Glass blowed 0g habitats (Score 1) 88

> Isn't your home a lava gas home made with mirrors?

My house is brick on the outside, and making brick involves heating it to where it starts to melt. Historically that's been done with a furnace, but there is no fundamental reason it can't be done with concentrated sunlight.

As a practical matter, the Sun doesn't always shine on Earth, but it does in space. The heating cycle for bricks takes longer than a day, so using sunlight is complicated.

Comment Space Station -- Deep Space Habitat timeline (Score 1) 88

This sounds like the Space Station Phase B (preliminary design) contracts we worked on back in 1986-1987. We built some prototype modules back then too. Then it took a decade, from '88 to '98, to get to first hardware launch. Based on that history, look for first Deep Space Habitat launch in 2028.

Comment Re: Good (Score 3, Interesting) 534

> When in reality, the best experience is an ad-free experience.

That's not always true. I do hardware design, and enjoy woodworking, and read paper magazines related to both. I find the ads in those magazines useful, because they are very relevant. Now, if I found a penis enhancer ad in either magazine, that would be bad.

If Facebook or any other site offered a checklist of ad topics to serve me, I would find that reasonable. I could pick the ones I was interested in, and not see the rest.

Comment Re:Delayed due audit?!?! (Score 1) 65

> Then there's no one left to care enough to prevent the US private industry from delivering heavy lift vehicles that will actually get used.

Space industry in total was $335 billion in 2015 ( http://www.sia.org/wp-content/... ), two-thirds of which are satellite-based. There were 1,381 active satellites by the end of last year. NASA just isn't driving space development any more. They account for a little over 5% of the total. A rocket like the Falcon 9/Heavy is a good combination to address the whole market. Falcon 9 for the majority of launches, and Falcon Heavy for the occasional ones that need bigger payload mass. Since the Heavy uses the same production line, it doesn't get penalized much for a lower flight rate.

Comment Re:In order to get your ass to Mars. . . (Score 1) 65

Space systems engineer here. Overall these are good ideas, but I think the mission sequence and technical details are slightly off:

* Near Earth Asteroids (NEA) are easier to start with. They can be reached entirely with electric propulsion, while landing on the Moon requires chemical propulsion. The latter require about 10 times as much propellant for the same mission velocity. To reach an asteroid you can use the Moon itself for a gravity assist, so the delta-V to reach the well-placed ones is actually lower than reaching the Lunar surface.

* The mass return ratio of an electric tug fetching rock from NEAs is about 200:1 over it's operating life, assuming you mine some of the returned rock for propellant for later trips. Up to 20% of the rock is water and carbon compounds. These can be reformed to oxygen + hydrocarbons, which is high thrust chemical fuel. This fuel can then be used to land on the Moon, or other missions that need the higher thrust levels. 20% x 200:1 means the yield of chemical fuel can be 40:1.

* Processing rock to useful products is best done in open space where you get sunlight 100% of the time. The Lunar surface only averages 50%, and polar craters where ice freezes out get 0%, which is why they are cold enough to trap ice.

* Five out of six discovered NEA are larger than 30 meters in size ( http://neo.jpl.nasa.gov/stats/ ), which means their mass is a minimum of 18,000 tons, and ranges much higher depending on composition and size. These are too massive to move, so mining will be a surface-scraping operation at first. Dust and pebbles will be easier to run through the processing equipment. Hollowing out natural asteroids is not a good idea, because most of them are the end result of multiple impacts. They are very likely structurally flawed. Placing smaller pieces in storage lockers *around* fabricated modules can provide radiation shielding and hold pressure more safely.

* Once you have access to the Lunar surface, set up a centrifugal catapult and launch bulk materials into orbit for processing. You want to use both Lunar and NEA raw materials because they have different histories and compositions. Lunar launch, even with 50% sunlight, has much higher mass return ratios and shorter transit times, so you definitely want it as an upgrade.

* Definitely bootstrap mining and processing wherever you go. There are just as many asteroids near a Mars Cycler orbit as near Earth, our home planet is not special in that regard. So a tug can fetch raw rock to your cycling habitat for radiation shielding and later processing. Phobos is a very large resource to mine, and it is likely to have water and carbon compounds (we need to actually visit it to be sure.

* Again, the general idea of bootstrapping mining and production from local materials is very much right. The leverage on not having to bring everything from Earth is huge.

Comment Re:I'm totally shocked... (Score 1) 614

> Now the long slide since 2008 will continue until some disruptive element creates economic opportunity.

Personal automation in the form of machines that can make more machines, which in turn make the stuff you need. Jobs and income will go down, because stuff you make for yourself isn't counted as work or income. Despite that, production will go up and people will be better off.

For example, automated machine shop and foundry makes robot farm tractors, among other things. The tractors in turn grow food for the owners. Since the machine shop is too expensive for the average person, they would be run as cooperatives, like my power company and credit union are. When you make your own stuff using your own equipment, you get to skip all the middle-man markups and profit, and you don't pay income or sales taxes on it. You are also immune to layoffs, because you own the equipment. You don't have to work very hard for it, either, because the equipment is mostly automated. A regular farm tractor can produce food for 50 or 100 people, an automated one can do at least as well. You still need a farmer to oversee the tractors and decide when to plant and harvest, but for most people the food just shows up on a regular basis.

Comment Re:Bitcoin? Yes. TOR? NO! (Score 2) 103

Actually, Day One for Bitcoin was buying two pizzas for 10,000 BTC, and that was 18 months after the network first booted up. Until then it was just a cryptographic curiosity. The Silk Road prosecution revealed that only 4% of bitcoin transactions were used on their black market to buy drugs and other nefarious purposes. That's not much higher than the ratio of illicit drugs to GDP worldwide (3%), and is far less than the total underground economy in the US (20%). The underground economy = black market (illegal) + off the books economy (nominally legal but not reported).

Good old cash is still by far the preferred choice for illegal activity. That's why over 70% of hundred Dollar bills are overseas:

http://www.npr.org/sections/mo...

Comment Re:Sharing is a business now? (Score 2) 103

> All transactions are recorded in the block chain and supposedly available for inspection by anyone.

Yes, they are. But they only record the sending address, receiving address, and the amount being sent. No names or other personal information. Here, look at a transaction from the most recent block, and tell me anything about the people involved:

https://blockchain.info/tx/ce1...

Comment Re:Other motivations (Score 2) 164

> (you could "make" more money by stuffing it under a mattress, than by using it to do something economically productive).

That's only true if the rate of deflation was greater than the nominal rate of return on other investments. Stock earnings, as measured by the S&P 500 have grown at an average of 6.6% over the last 55 years, plus paid out a few percent in cash dividends on top of that. If the dividends were re-invested, then total earnings would grow around 8.8%. If your money were deflating at 2% you would be far better off with stocks.

Slashdot Top Deals

Genetics explains why you look like your father, and if you don't, why you should.

Working...