Kdybyste nahodou, tak jako ja, sedeli na zachode a rekli si "Huh... proc ne L4/L5, kdyz ty jsou prece stabilni?", tak odpoved je pochopitelne na interwebech:
https://space.stackexchange.com/questions/284/why-should-the-james-webb-space-telescope-stay-in-the-unstable-l2 :
There are a couple of reasons.
- The distance from the L2 to Earth is only 1.5 million km away. The L4/L5 are 1 AU, or about 150 million km away. That leads to a reduction in link margin of 40 db, or 1/10000. That is quite significant. In order to compensate for that difference, you either need a bigger radio dish, more power, or a loss in data.
- As you mentioned, the fuel usage is quite low to maintain that position, only on t.order of 150 m/s delta v for the entire mission. That isn't a whole lot, and in fact, is less than what is required to keep a satellite in geostationary orbit.
- The satellite is much closer, reducing the time to command an object. Light only will take 5 seconds to reach James Webb, whereas it will take 9 minutes to reach L4/L5. This limits the ability to do real time commands, which occasionally are useful (Think Gamma Ray Bursts, Super Novas, etc)
Bottom line is, the communication problem is simplified with a closer telescope, and that more than makes up for having to take a bit more fuel.
Pro me nejdulezitejsi je, ze ze vsech tech schematickejch obrazku neni videt ten velmi obrovskej rozdil mezi vzdalenosti Zeme-L2 a Zeme-L4/5 ... plus jsem necekal, ze celkova delta-v pro station keeping je tak nizka.