Let'sgoflying!
Touchdown! Greaser!
Cloth in fuel line almost wrecks day.
Space: hate those little $15M mistakes!
- Thread starter Let'sgoflying!
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steingar
Taxi to Parking
Hate it when that happens.
Nice save, they probably have more fuel left this way too.
John Baker
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"Losing AEHF-1 would have been a costly and embarrassing blow. It would have delayed the satellite system along with all the related technology that will use it, and it would have prolonged the military's dependence on the aging Milstar system, first launched in 1994."
Wow, they are replacing a multi billion, more than likely trillion, dollar system that is all of seventeen years old, that is apparently still working just fine.
What is this? Is it like the I phone? Us tax payers sure are a fickle lot, we gotta have the latest gadget or we ain't cool? Sure glad we're rich.
-John
Wow, they are replacing a multi billion, more than likely trillion, dollar system that is all of seventeen years old, that is apparently still working just fine.
What is this? Is it like the I phone? Us tax payers sure are a fickle lot, we gotta have the latest gadget or we ain't cool? Sure glad we're rich.
-John
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jtheune
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As the article said, it give more capacity and resist jamming. The current system is not working just fine becuase the requirements for it have changed. More bandwidth is needed for the current generation of technology.
wanttaja
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Spacecraft are just like any other vehicle...they burn fuel, and they age. They require propellant to maintain their correct position, bearings wear and eventually seize up, and solar arrays deteriorate and produce less power.
If the bearings on a Control Moment Gyros (CMG) freezes, the spacecraft can't maintain its attitude and thus can't point its high-gain antennas towards the Earth. Similarly, if a bearing in an antenna gimbal locks up, the antenna can't be aimed. If the S/C is in GEO (like Milstar) and runs out of fuel, it drifts towards one of the two Stable Points and starts waggling north and south...both of which interfere with operating as a communications satellite. If the solar arrays don't produce enough power, the spacecraft can't operate the high-power amplifiers necessary to maintain high-rate communications.
The individual Milstar vehicles are designed for a ten-year life. Margin is put atop that which enables longer operation, if needed. It's not uncommon for individual satellites to greatly exceed their design limit, but it's not something a wise planner counts on.
Remember, there is no opportunity to service and repair anything. That's ten years on the original lube in the CMGs and the antenna gimbals, no way to get the propellant residues and outgassing products off the solar arrays, and no way to re-fuel. Imagine an airplane that can operate 24/7 for ten years on that basis....
Ron Wanttaja
airguy
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Yup - now let's look at the other side of that same coin. All of a sudden you can't get a GPS fix because a sufficient number of GPS satellites have died in orbit and become non-functional, and then somebody finally wakes up and says, "Oh hey, we need to replace that satellite, it's dead..." and begins the 24-30 month process of doing so. Isn't it much preferable to have the spare satellite already in orbit and waiting to take the place of the next dead satellite in the constellation?
Now - let's up the ante a bit more shall we? Let's assume that rather than something relatively benign like a GPS satellite (in my scenario above) this is actually a military communications satellite - that our military depends on to keep us operational (as is the case in reality). Wouldn't that make it be just a BIT more important to be ahead of the curve?
That alone should make the case very nicely - but there is yet another wrinkle to add to this puzzle. Even if everything went fine with the existing satellite and no failures occur, it is constantly using fuel for station-keeping. At some point fuel will run out and it will be useless. The problem is, when that occurs, it's out of fuel and useless, and still parked in the orbit that its replacement needs to be in. For that reason when satellites reach a "bingo-fuel" situation in GEO, they are typically decommissioned and the remaining fuel is used to move them into a disposal orbit, to make room for the next standby satellite to move into its position. The satellite manufacturers have that fuel requirement to move it into disposal orbit pre-calculated, and when you hit that point you have to decommission and scrap it to keep the orbital position clear while you still have control over the bird.
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The Milstar system does not have the capacity for going forward. We add more an more demands on the satellite system with all the data being linked around to all the different platforms; demands that increase every day and with every new platform.
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