Five days ago a presser came out about deep-space communications, through "optics" meaning, beamed lasers. On the same day Paul Gilster mused on the Pointing Problem.
Basically once you get out to Arrakoth at, what, 45 AU it's hard to send your data to 1 AU. We're talking roughly six light-hours from the Sun. And then there's inverse-squares attentuating the signal. That problem is so hard I'm restricting my blog to 5-6 AU.
NASA are testing something as can boost bandwidth on the Psyche mission whenever that is. The delay has allowed for better physics to come into scope, and - further - has biased said physics for time-savings, here on the back-end of the mission. The power-levels are still 5 W because - hey, why not, it's just Psyche 2.9 AU. Malcolm Wright is presenting his data this Thursday 10:45 AM, Catalan time.
Gilster starts with moon Europa from almost twice Psyche's average distance. I'm not even considering how to unobfuscate a signal from Jupiter's radiation; for my purposes I'll head to Callisto instead. So, let's say, a third the signal-strength as the Psyche proposal. So what; boost the wattage to 15-20 W. I need three times more battery: every-gram-counts, yo.
Gilster figures we can remove a lot of waste with a tighter beam and better beam accuracy.
Once we've firmly sussed Callisto/Venus communications I'll further suggest relays at the Trojans SJL4 and SJL5. This should shave 5ish AU from Venus-to-Outer communications. By inverse-squares every AU counts. Admittedly we incur a latency cost. Covering a third of a circle (120°) swinging around 11.86 Earth years, we further must time it all right.
No comments:
Post a Comment