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Every time theres an amateur radio story posted to /., either about morse code or BPL, all these haters show up and start saying ham radio is dead and that its a waste to give all these airwaves to these "hams".

Where are the haters in this thread? Oh OHHH its because we launched a ROCKET INTO SPACE. Has your hobby done that? HMM!? What about dozens of satellites, space station experiments and space shuttle experiments? What about being a vital part of our nation's emergency communications network?

I didn't think so. To all the rest, thank you for the resepect. I'm not trying to say ham radio is the best hobby, I'm just saying the haters need to recognize. :P

get fine people like these to help them.

The handset design is one thing, but I'd really like to see the design of the satellite.

Since the article discusses the use of a single satellite, for use by Korea and Japan only, one concludes that the satellite must be in geosynchronous orbit (otherwise there would be service outages as it passed behind the earth). That puts it 22,300 miles up (in the Clarke Belt).

Since the Clarke Belt is so far away, a combination of

high transmitter power in the satellite,

good sensitivity (low noise figure) in the receiver back on Earth, and

high antenna gain at both transmitter and receiver

are typically used to make the link work. Modern satellite television (e.g., DirecTV) uses a relatively high frequency of operation (12 GHz) so that high antenna gain can be achieved in a physically small (i.e., less than two foot diameter) package. However, the article says that the proposed system operates at 2.6 GHz. This would seriously kill any hope of significant antenna gain at the receiver, even if one could design a gain antenna that could track a satellite in a mobile, handheld system.

Said another way, in the DirecTV system, the typical Earthside antenna has a gain of about 33.5 dBi. The handheld antenna gain will be doing well to reach 0 dBi. Since the DirecTV receiver has a noise figure of only 1 dB, no receiver sensitivity improvement is possible there. The only way to get back the 33.5 dB of link margin is to either increase the satellite's antenna gain by an additional 33.5 dB (which would make it impractically large, especially given the low frequency of operation, and give it a very small footprint on the Earth's surface) or increase the transmitter power by 33.5 dB (or 2239x).

How is the system to work?? Does anyone have a link margin calculation for this system?

One interesting insight: after the Challenger explosion it became obvious that we would never refuel a rocket with volatile fuel at a space station because the threat to the station would be so great.

Volatile fuels like, say, liquid hydrogen and oxygen? Yeah, that's scary. Really 'volatile' stuff.

Everyone who saw Challenger's loss--remember what it looked like? Try here if not. No huge fireball (for the size of the vehicle, anyway) like you'd expect from truly 'volatile' fuels. There was a good amount of fire, but I believe most of the fuels were converted to steam. Even the fuel in the solid rocket boosters (ammonium perchlorate and aluminum) isn't what I'd call 'volatile'--it's designed to burn steadily. The hydrazine used for the OMS engines (and RCS thrusters, IIRC) is another issue--hypergolic fuels are quite dangerous (remember those old WWII videos of German V-2 rockets falling over and exploding?), but there's not all that much of them.

At any rate, the cause of Challenger's loss was the destruction of the external tank's structural integrity, which allowed the liquid hydrogen (and oxygen) to escape and ignite. I'm relatively certain the ISS already has LOX and liquid H2 tanks for the fuel cells (unless all power comes from the solar panels) and oxygen/water generation. What's the issue?

Granted, if we're talking about the shuttle, it doesn't use its main engines after orbit insertion (as the fuel tank is jettisoned), so all it's got is the OMS engines, and like I said--hydrazine is nasty shit. I can understand not wanting a bunch of it stored on the station. Linking that to Challenger doesn't make sense, though--it wasn't hydrazine that killed them.

Of course, they could park a few tanks a safe distance away if they could keep them in the same orbit. Maybe at the L1 point that would work, but we're into a whole new argument there...

--Ty

See: this article in Space Today on SIRTF.

India is planning to send a mission to moon by 2008, and they very well accept that it is just for the we too can factor.
Rare to see that kind of admission from politicians

(simplistic but readable discussion thereof)

Equator, since (a)the Earth is an oblate spheroid and the Equator is higher than the poles (b) slingshot effect wouldn't apply at the poles. Same logic explains the Russian sea launches which allow rockets to save a chunk of fuel by getting as equatorial as possible and the French using Guyana for Ariadne.

If they're from Russia they're cosmonauts. That said, they have, IMO, worse food than American astronauts. But then again, I'm not Russian so I can't appreciate the succulent flavor of sturgeon with jellied sauce or chicken paste with plums. Much more info is available on this page.

Astro/cosmo-nauts tend to lose their appetites and experience changes in their sense of taste after 60 to 80 days anyway, so the gourmet stuff is most useful at the beginning of the trip. After that, a much less, um -- subtle -- approach is required. According to this story people in space crave spicy, garlicky food as their sense of taste diminishes (Cosmonauts asked NASA to send garlic and onions).

But in the end, any trip to Mars will have to grow its own food. This story from last year about the Russian Mars plans mentions that this is exactly what they intend to do. Mmmm...wheat and quail.

To see a QuickTime movie of the explosion click here