National Academies Press: OpenBook
« Previous: 4 The Threshold for Transformational Science
Suggested Citation:"5 Minimum Number of Antennas." National Research Council. 2005. The Atacama Large Millimeter Array: Implications of a Potential Descope. Washington, DC: The National Academies Press. doi: 10.17226/11326.
×

5
Minimum Number of Antennas

Millimeter and submillimeter observations are very important to contemporary astronomy. No better defense of this proposition is needed than the list of advances in the 15 years that have elapsed since the 1991 astronomy and astrophysics decadal survey was written. Nonetheless it is legitimate to ask at what point a descoped telescope would fail to sustain support in the highly competitive environment for new facilities today. This committee’s answer, inevitably somewhat subjective, is based on the performance measures presented in Table 1. Table 1 shows, for example, that a 30-antenna array has only 3 to 4 times the sensitivity of Plateau de Beure at wavelengths longer than 1 millimeter and would not have ALMA’s potential enormous mosaicing speed advantage at high frequency over that of the Submillimeter Array (SMA), which is the one other high-altitude facility capable of observing at 900 GHz.

The committee concludes that a 40-antenna array would retain ALMA’s strong support within the general astronomical community. However, the rapid decline in imaging capability that would result with a further reduction below 40 antennas would erode this support.

Suggested Citation:"5 Minimum Number of Antennas." National Research Council. 2005. The Atacama Large Millimeter Array: Implications of a Potential Descope. Washington, DC: The National Academies Press. doi: 10.17226/11326.
×

This page intentionally left blank.

Suggested Citation:"5 Minimum Number of Antennas." National Research Council. 2005. The Atacama Large Millimeter Array: Implications of a Potential Descope. Washington, DC: The National Academies Press. doi: 10.17226/11326.
×
Page 21
Suggested Citation:"5 Minimum Number of Antennas." National Research Council. 2005. The Atacama Large Millimeter Array: Implications of a Potential Descope. Washington, DC: The National Academies Press. doi: 10.17226/11326.
×
Page 22
Next: Appendix A: Letter of Request »
The Atacama Large Millimeter Array: Implications of a Potential Descope Get This Book
×
Buy Paperback | $21.00 Buy Ebook | $16.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

The 1991 NRC decadal survey for astronomy and astrophysics included a project called the Millimeter Array (MMA). This instrument would be an array of millimeter-wavelength telescopes intended to capture images of star-forming regions and distant star-burst galaxies. With the addition of contributions form Europe, the MMA evolved into the Atacama Large Millimeter Array (ALMA), a proposed array of 64, 12-meter antennas. The project is now part of the NSF Major Research Equipment and Facilities budget request. Increased costs, however, have forced the NSF to reconsider the number of antennas. To help with that review, NSF asked the NRC to assess the scientific consequences of reducing the number of active antennas from 60 to either 50 or 40. This report presents an assessment of the effect of downsizing on technical performance specifications, performance degradation, and the ability to perform transformational science, and of the minimum number of antennas needed.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!