Space stellar parallax measurement missions:
    1. The European Space Agency (ESA) satellite Hipparcos (operational 1989--1993) had the capability of measuring parallaxes as small as about 0.01 arcseconds with 10 % accuracy and and 0.005 arcseconds with 20 % accuracy (Hipparcos summary): 
        d_max = 1/theta_min = 100 pc  with 10 % accuracy for about 20,000 stars;

  d_max = 1/theta_min = 200 pc  with 20 % accuracy for about 50,000 stars.
      Hipparcos distances out to about 500 pc were measured with lower accuracy (FK-587)???.

      Unfortunately, there seems to have been some calibration errors that left some distances very pseudo-precise, but NOT accurate????.

    2. NASA planned to launch the Space Interferometry Mission (SIM) sometime in the 2010s.

      Among other things, SIM was planned to be able to measure stellar parallaxes as small as 4*10**(-6) arcseconds. Note 

        d_max = 1/theta_min = 1/4*10**(-6) = 2.5*10**5 pc

        = 250 kpc .

      The disk of the Milky Way has a diameter of about 30 kpc (CK-379) and nearby dwarf galaxies are within about 300 kpc (FK-593).

      Thus, SIM would have given us distances all over the Milky Way and to nearby dwarf galaxies.

      It would NOT have been able to reach the nearest large galaxy, the Andromeda Galaxy (M31) at about 725 kpc (Cox-578).

      Alas, SIM was been defunded as of 2010 Sep24.

      SIM or a similar project might be revived at a later date.

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