Loading ...
Sorry, an error occurred while loading the content.

97766Re: [sfconsim-l] Earth-Lunar L1 / Diego Garcia

Expand Messages
  • Scott M
    Apr 30, 2014
    • 0 Attachment
      I contacted the communications person for the Keck telescopes in Hawaii and asked a few detailed questions.  He sent me back the following.

      (note: the ship in question is 1 mile long, about 250 yards wide)

      L1 for the Earth–Moon system is 345,000 km from the center of the Earth, between the Earth and the Moon. At that distance, 1 mile (1.6 km) subtends approximately an arc second (arcsec). The median image size at WMKO is 0.6 arcsec, so with most of our instruments the length of the spacecraft would be barely resolvable.

      With adaptive optics, of course, we can do much better, 0.055 arcsec, for instance. This is enough to be able to tell the shape, for example.

      Would one or both Keck telescopes be redirected? Maybe. It’s a hard question to answer because it has never before occurred. 

      Note, too, that the Advanced Electro-Optical System Telescope located on Haleakala, Maui uses adaptive optics, and could give images of about 0.16 arcsec size. Since it is controlled by the Dept. of Defense, it is highly likely they would look at such a target.

      On Tue, Apr 29, 2014 at 12:12 PM, Scott M <steppahouse@...> wrote:
      The number of dentists named Macintosh is somewhat surprising, lol.

      On Tue, Apr 29, 2014 at 12:09 PM, eric henry <ehenry0623@...> wrote:

      Paging Dr Macintosh...

      On Tue, Apr 29, 2014 at 11:38 AM, Scott M <steppahouse@...> wrote:

      I was revisiting this issue as I had some story time-line constraints change and was reviewing all data that would be affected by that change.  One thing occurred to me right away, mostly due to research subsequent to this discussion from December.  The "first-contact" event happens in October 2016.  Hubble won't be a factor at that point.

      Plus, given the time of day (0730 on the American east coast, 0430 on the west coast) Diego Garcia wouldn't see it for a couple of hours too late.  The original setup had a Chinese amateur see it first just after moonrise, approximately 1815-1830 (UTC+8...still a lot of light in the sky, particularly to the west, but I have to make some arbitrary choices somewhere).  By the time DG rotates into view of the ship, most of the initial flurry of events have already taken place.

      I could use the Keck Observatory in Hawaii, but I'm not sure how an optical/infrared setup that's designed for deep space viewing would handle something that close.  Common sense says closer=better, but I don't know all the in's and out's.  I emailed their info office and am waiting on a response.

      On Tue, Dec 10, 2013 at 11:14 AM, Isaac Kuo <mechdan@...> wrote:

      >I think what we're looking at, then, is whether or not the U.S. leadership would have first-hand "eyes on" without having to rely on other feeds.  GEODSS at Diego Garcia was the closest I could come up with, assuming that Hubble and Spitzer (JPL assets) were on the wrong side of the planet to see this thing.  I'm assuming the latter arbitrarily, although it wouldn't hurt to see what Hubble and Spitzer's orbits look like, ie, if they are ever actually both blocked from seeing the L1.

      Spitzer is in an Earth trailing orbit, and it can't view in any
      direction closer than 80 degrees to the Sun.  This means that
      for the next 10 years, Spitzer can see everything around Earth
      at any time, except if it's blocked by Earth itself or the Moon.
      Due to the inclination of the Moon's orbit, it's really unlikely
      that the object would be blocked.

      However, after another 10 years, Spitzer won't be able to point
      at Earth at all...and not again until the Earth catches up with
      Spitzer (in another 30 years).

      So, you can simply set the story in another 10 years or so to
      avoid Spitzer's gaze.

      Hubble, OTOH, is in Earth orbit.  It's in a typical prograde
      orbit, circling Earth about once every 1.5 hours.  As such,
      Hubble will have a direct line of sight with the object
      within minutes.  However, Hubble can't point near the Sun.
      If the object were to appear near the Sun in the sky (new
      Moon), then Hubble wouldn't be able to view it.

      Isaac Kuo  mechdan@...

    • Show all 15 messages in this topic