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Comment Re:It's all good until (Score 1) 245

Most likely this would be restricted to countries like the US that have a huge amount of space that's largely uninhabited. Unfortunately, I'm not aware of any such nation that's also located close enough to the equator to have a geosynchronous orbit. IIRC, you really need to be within about 10 degrees of the equator, or something like that. If you get too far away, then the speed necessary to keep the satellite in orbit prevents it from staying directly above the receiver.

Countries with lots of space and located close to the equator. You are aware of none ? You should take a closer look. Anyway, you don't need to be close to the equator to be a "target" of a geostationnary satellite. (TV service using GEO are covering Alaska or Norway) But the more away from the equator you are, the more inclined the beam will be, and you lose (horizontal) surface efficiency.

Comment Re: Hubble gyros (Score 1) 73

There seems to be a problem with the engineering teams developing gyros and reaction wheels for US spacecraft. They used to get better with every iteration, back in the day...

It's not only for US spacecraft. I was working a few years back for a French spacecraft manufacturer, and we have got 4 wheels failure in the first 6 month after launch, on 6 spacecraft (so 4 failures out of 24 wheels.) Ok you could call it US spacecraft, because it was done for an American customer, and the wheels were coming from the US(or was it the UK ? not sure, but I think US.) On the other hand, it was "low cost" satellite, and "low cost" wheels.

Comment Re:A partial success (Score 1) 73

You are right, but it's TFA (first link, NASA press release) which says

Two of Kepler's four gyroscope-like reaction wheels

which is an inaccurate description of reaction wheels.

(for those interested, in short : you can use a RWA (A is for Assembly) to provide gyroscopic stiffness to a spacecraft (in that case you could maybe speak of gyroscope-like). But you can also use the RWA for 3 axis pointing (precise pointing, not just gyroscopic stability) in that case it's not a gyroscope. You just transfer angular momentum from the spacecraft to the wheels. The three axis pointing could still include gyroscopic stiffness from the wheel, but it's not only that)(I know, I use too many parenthesis)

Comment Re:A partial success (Score 4, Informative) 73

You can control attitude using (ion) thruster, but reaction wheels have some advantages. One of the biggest advantage of RWs is that it's (close to) a linear actuator (outside of the zero crossing zone), where thruster are bang bang actuators. In fact they are bad bang bang actuator, because you have some transient at start and end of the pulse.

Comment Re:Umm... (Score 3, Insightful) 86

There are also COTS technology order of magnitude cheaper and better for space technology that was available during the cold war. Not for all subsystems, but for some of them. You have higher specific impulse technology (but low thrust, bad point for human mission, but good for mass), cheaper sensor (anything you want, gyro, sun, star, ... you could not have found that easily before, now it's just about making a few phone calls and cash, it's not cheap, but also not millions of $), you can find better space hardened processors/ram which are not comparable to what was available during cold war.

You can also book a launch to earth suburbs "easily"(still expensive) but if this is from Copenhagen Suborbital, I suppose that they want to use their own launcher, if they finish this project)

On the other hand, there are still a lot of place where not a lot of progress have been made, like radiation protection which must still be massive, because humans have a tendency to die easily. Maybe we can change humans ?

They speak of a time frame of 30 to 50 years, 50 years being more than the time between Sputnik and the ISS

Will they make it in 50 years ? Probably not. But it's a hobby, you still have to do something in your free time, no ? And even if it's not a hobby but a paid job, there is not enough job on earth if people only do useful stuff, so why not trying to do something else ?

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