Comments on: Alpha and Proxima http://oklo.org/2006/06/24/proxima-and-alpha/ characterizing planetary systems Wed, 18 Apr 2012 18:53:22 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: systemic - speculations http://oklo.org/2006/06/24/proxima-and-alpha/comment-page-1/#comment-346 systemic - speculations Fri, 29 Sep 2006 23:36:22 +0000 http://oklo.org/?p=101#comment-346 [...] Finally, it’s always good to look at costs. According to the Wikipedia, the total cost of building, launching, servicing, and running HST has been of order 6 billion dollars. It started working as planned in 1994, and will thus have ~15 years of fully functional use. The seven days of ACS time were therefore worth 7.6 million dollars. This is comfortably more than the cost of building a special-purpose telescope to probe the terrestrial planets that are almost certainly orbiting Alpha Centauri B. (For more information, see these oklo.org posts: 1, 2, 3, 4, 5.) [...] [...] Finally, it’s always good to look at costs. According to the Wikipedia, the total cost of building, launching, servicing, and running HST has been of order 6 billion dollars. It started working as planned in 1994, and will thus have ~15 years of fully functional use. The seven days of ACS time were therefore worth 7.6 million dollars. This is comfortably more than the cost of building a special-purpose telescope to probe the terrestrial planets that are almost certainly orbiting Alpha Centauri B. (For more information, see these oklo.org posts: 1, 2, 3, 4, 5.) [...]

]]> By: systemic - A Million-Year Picnic http://oklo.org/2006/06/24/proxima-and-alpha/comment-page-1/#comment-187 systemic - A Million-Year Picnic Mon, 03 Jul 2006 15:15:54 +0000 http://oklo.org/?p=101#comment-187 [...] Last week, I wrote about a plan to send a tiny spacecraft on a trip to the vicinity of Alpha and Proxima Centauri. The idea is to employ a multi-stage rocket to boost a tiny payload toward the stellar system at high speed. When the destination is reached, the principle of gravity de-assist (in the form of successive close flybys of the stars) is used to haul the spacecraft into a bound orbit without using any on-board fuel. [This, of course, is an exercise in orbital dynamics, and not mission proposal. There are better ways to get to Alpha Centauri.] [...] [...] Last week, I wrote about a plan to send a tiny spacecraft on a trip to the vicinity of Alpha and Proxima Centauri. The idea is to employ a multi-stage rocket to boost a tiny payload toward the stellar system at high speed. When the destination is reached, the principle of gravity de-assist (in the form of successive close flybys of the stars) is used to haul the spacecraft into a bound orbit without using any on-board fuel. [This, of course, is an exercise in orbital dynamics, and not mission proposal. There are better ways to get to Alpha Centauri.] [...]

]]> By: greg http://oklo.org/2006/06/24/proxima-and-alpha/comment-page-1/#comment-179 greg Mon, 26 Jun 2006 17:55:59 +0000 http://oklo.org/?p=101#comment-179 Paul Gilster over at Centauri Dreams was a bit puzzled about the 79 year interval between double sunrises that would occur for the as-yet undetected Alpha Centauri A b. My thinking was that given the 79-year orbital period of A and B, they will have a roughly 79-year interval between conjunctions as seen from a non-co-planar planet in a relatively close (e.g. habitable) orbit around either star. The conjunctions would lead to a period where the stars appear very close together in the sky, hence the "double sunrises" (and double sunsets). Upon getting Paul's e-mail, I realized that there will be two node crossings per 79-year orbit, leading to two conjunctions per 79 year binary orbit. I've thus changed 79 to 39.5 in the post. -Greg Paul Gilster over at Centauri Dreams was a bit puzzled about the 79 year interval between double sunrises that would occur for the as-yet undetected Alpha Centauri A b.

My thinking was that given the 79-year orbital period of A and B, they will have a roughly 79-year interval between conjunctions as seen from a non-co-planar planet in a
relatively close (e.g. habitable) orbit around either star. The
conjunctions would lead to a period where the stars appear very close together in the sky, hence the “double sunrises” (and double sunsets).

Upon getting Paul’s e-mail, I realized that there will be two node crossings per 79-year orbit, leading to two conjunctions per 79 year binary orbit. I’ve thus changed 79 to 39.5 in the post.

-Greg

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