Major Science Themes and The Cost to Complete SIM

Here is an article that summarizes the estimated cost to complete SIM and the areas of astronomy that will be helped by SIM.

      SIM Lite Astrometric Observatory - 2009 Summary

   This report tells the story of the science, and of the status of technology development, as of 2009.  In addition, on page 19, one can see that JPL estimates that it will cost only $740 million to complete Phases C and D.  This is essentially equivalent to one of NASA's New Frontiers missions.
This does not include the price of launch.  However, it is possible that SIM could be launched by ESA's Ariane 5 in an agreement with that agency.  In a future post, I will describe collaboration that has already occurred between ESA and NASA on SIM's astrometry system.   If the SIM project is terminated, then ESA will reap the rewards of JPL's, and NASA's, large investment in the design of this system.
    This report's estimates of the cost to complete SIM should be more reliable than that of most space projects.  This is a result of the time (~ 12 years) and money (~$590 million) invested in refining SIM's design, and in working down the engineering risks.  A future entry will review the engineering milestones that NASA set before the SIM team, and how that team successfully met every milestone.
As mentioned above, the United States stands to abandon this effort and to let the Europeans take the lead.  I don't mean to be jingoistic in this blog, but as an American citizen, I would like to see my country  maintain its technology and scientific edge.


   As for the science of SIM, the subtitle on this report's front page says it all - "From Earth-Like Planets to Dark Matter."  SIM will be a fantastic discovery machine.  It will not only search for nearby Earths, it will make major contributions to our understanding of a variety of astronomical subjects.  Here is a list of SIM's Science Themes, listed on page 1:

- The Search for Habitable Worlds

- Dark Matter and the Assembly of Galaxies

- Precision Stellar Astrophysics

- Supermassive Black Holes and Quasars

- Charting the Uncharted Waters

    As the last item implies, perhaps SIM's greatest contribution to science will be a discovery that we cannot predict.

    This report also summarizes the engineering that goes into making SIM a modern marvel.  As noted in the report, the SIM team completed its stunningly successful technology development program in July 2005.  Since then, the team has concentrated on reducing engineering risk.  Flight-qualifiable versions of key hardware elements were built and tested.  As a result of this work, SIM is technically ready to for full-scale development.

I Could Not Sleep For Thinking of the Sky

  There is a poem by John Masefield that I think encapsulates the emotion of those who search for other Earths.   The title is "The Unending Sky" and here it is -

   I could not sleep for thinking of the sky, 
   The unending sky, with all its million suns
   Which turn their planets everlastingly
   In nothing, where the fire-haired comet runs.  


   If I could sail that nothing, I should cross 
   Silence and emptiness with dark stars passing,
   Then, in the darkness, see a point of gloss 
   Burn to a glow, and glare, and keep amassing,  


   And rage into a Sun with wandering planets 
   And drop behind, and then, as I proceed,  
   See his last light upon his last moon's granites 
   Die to a dark that would be night indeed.


   Night where my soul might sail a million years 
   In nothing, not even death, not even tears.  

The Case for SIM

   I authored an online article that appeared on the "Space Review" website recently.  It can be found here-

SIM and the "Ready, Aim, Aim" Syndrome


  In addition, Paul Gilster, on his "Centauri Dreams" web site, wrote an excellent article about SIM and my Space Review essay.  His contribution can be found here -    

Losing SIM: Thoughts on Exoplanet Strategy


   To the readers of this blog, I ask you to submit comments on why we should proceed with SIM, as opposed to the advice from the Astro 2010 Decadal Survey.  There are many in the space community who agree with the conclusions of Astro 2010.  I am not one of those.  However, I would like to hear your thoughts on this.

My thoughts on this subject turn mainly to the aspect of "good faith."  The members of the SIM team have devoted anywhere from 10 to 20 years of their professional careers to the project.  I think that this "gamble" was taken by them because of the assumption of "good faith" on the part of NASA.  One doesn't lightly decide to make such an enormous commitment of time and career.  It is only by believing that NASA headquarters will follow through on their promise to proceed to launch that one can make that leap.  I think that NASA has now breached that "contract."  The SIM team has delivered on their end by designing a capable and elegant spacecraft.  They have done everything asked of them.  They should not be punished for the good work that they have accomplished.

Taking the Measure of the Universe

 The following article is an excellent summary of the stunning science that will flow from the SIM mission.  As you can see, it will not only allow the discovery of habitable "Earths" that orbit nearby stars, but will contribute immensely to many fields of Astronomy.   The review can be found at  -

  Taking the Measure of the Universe: Precision Astrometry with SIM PlanetQuest


   After reading this paper, I think that you may agree with me that even if one ignored SIM's ability to find nearby Earths, then this mission could be justified solely by its ability to advance our understanding of stars, black holes, neutron stars, and other celestial objects.

Far Future of Exoplanet Exploration

   The journey that begins with SIM will eventually lead us to travel to nearby Earths.  The first visitors will be robotic and they will be sent to worlds that are discovered by SIM.  The closest solar systems will still be unimaginably far away, even when compared to the large distances between planets in our Solar System.  For example, Neptune, the farthest planet from the Sun, is located 30 AU from our star.  In comparison, 1 light-year is equal to 60,000 AU!  The closest star system, Alpha Centauri, is located at 4 and 1/2 LY from us, or 270,000 AU.   The vast emptiness between planetary systems presents a daunting challenge.
   However, even now, there are those who are proposing ways to cross that ocean.  The following is a link to an article by Ian Crawford.   The Reference section at the end of this paper is a very handy guide to the literature of interstellar flight.  

Comment on "The Far Future of Exoplanet Direct Characterization" - the Case for Interstellar Space Probes

    This paper reviews some of the technical objections to interstellar flight and makes the case that these can be overcome.  Crawford points out that any future detection of biosignatures in the spectra of nearby Earths will inspire the development of the technology required for such flight.
    I would add that the discovery of the mere existence of nearby Earths will inspire the creation of advanced space telescopes that will be able to detect those biosignatures.   SIM is the only mission that is designed to detect those nearby Earths.  It is the crucial 1st Step in the long road that will lead us to explore those nearby New Worlds, both by proxy and in person.

Long Twilight Struggle to Save SIM

  Today marks the beginning of the long twilight struggle to save the SIM space interferometer.  I am borrowing from Winston Churchill's description of the Cold War to emphasize that the effort to resuscitate the SIM project may be long and torturous.  However, I believe that NASA must eventually build and fly this elegant discovery machine.   The Space Interferometry Mission will produce stunning results in both exoplanet research, as well as basic astronomy.   In future posts I will link to a variety of studies that convey just how revolutionary this spacecraft will be.   To start, here is the link to a brief description of the discoveries that SIM will make in exoplanet research and general astrophysics.  The full title of this study is "SIM PlanetQuest: The Most Promising Near-Term Technique to Detect, Find Masses, and Determine Three-dimensional Orbits of Nearby Habitable Planets."

SIM PlanetQuest


   In the field of exoplanet research, SIM is the most important mission that NASA has proposed to date.  SIM will give mankind the ability, for the first time in history, to discover nearby Earth-sized planets.  In addition, SIM will be able to find new Earths which orbit their parent stars at the right distance to allow life to develop and flourish.

   So, let the fight for SIM begin!

Philip Horzempa