Quote from: speedevil on 09/07/2018 10:07 amStarshade costs may be capped by the cost of using an actual spacecraft to do it.If you can...If you could...Uh, look, no. If you take two low probability numbers and multiply them by each other, you get a lower number, not a higher one. So "if" times "if" makes something less likely. Take the BFS magical thinking to the threads where it already flourishes.
Starshade costs may be capped by the cost of using an actual spacecraft to do it.If you can...If you could...
Uh, look, no. If you take two low probability numbers and multiply them by each other, you get a lower number, not a higher one. So "if" times "if" makes something less likely. Take the BFS magical thinking to the threads where it already flourishes.
Quote from: Blackstar on 09/07/2018 03:50 pmQuote from: speedevil on 09/07/2018 10:07 amStarshade costs may be capped by the cost of using an actual spacecraft to do it.If you can...If you could...Uh, look, no. If you take two low probability numbers and multiply them by each other, you get a lower number, not a higher one. So "if" times "if" makes something less likely. Take the BFS magical thinking to the threads where it already flourishes. Out of 37,000 odd members in this forum there are none that have more credibility than you. But when it comes to anything SpaceX, I often can't even understand what you're saying. (Although, I do agree a BFS starshade doesn't make much sense)
when talking about a complicated piece of technology, claiming that it will be "made easier" by another piece of promised future technology is not credible.
Quote from: Blackstar on 09/07/2018 08:20 pmwhen talking about a complicated piece of technology, claiming that it will be "made easier" by another piece of promised future technology is not credible. A starshade, positioned by something else, is not actually a hugely complicated bit of technology.It is a very opaque thing, with no particular requirements other than the edges being reasonably not blunt (100um or so), of approximately the right form and diameter. The standoff distance makes this enormously easier than on-instrument coronagraphs or shades.Adding requirements makes it hard.For example, if it's got to fold into a space a hundredth of its area, and unfold multiply and weigh 200kg as you've spent the rest of the mass budget on an ion engine and bus to get it and keep it there, then it's hard.
As an aerospace professional who has personally done some analysis on this concept in the past, it is an engineering challenge but absolutely a solvable one. There is serious work being done right now at NASA Goddard among other places on the possibility of adding this to WFIRST. Precursor tech demos are already happening. https://www.nasa.gov/feature/goddard/2016/nasa-engineer-awaits-launch-of-cubesat-mission-demonstrating-virtual-telescope-techThe delta-V required for an occulter in a libration orbit can be high (but manageable) and ion engines or solar sailing can help. In my opinion this is now a when, not if, question. Of course the if depends on adequate prioritization and funding...
as does the solar radiation pressure on this huge, lightweight structure when you are trying to maintain extremely precise alignment with a telescope thousands of kilometres away. Not all observation geometries will be favorable or feasible at all times.
I'm probably missing something embarrassingly obvious here, but won't the sun lighting up one of these pretty, golden starshades be worse than the star it's blocking?
Is there any advantage of using a starshade with a telescope that has a coronagraph? (I mean to say using the internal coronagraph and the external starshade together.I think I read mention of that awhile back ago, but it seems to me that having a starshade would defeat the purpose of having a coronagraph.
Stupid question:Why are standard chronographs disk-shaped, rather than sunflower-shaped?