August 3, 2007

 

 

 

To the Public:

 

I am aware that a small minority of environmental activists are very concerned about the use of radio transmitters for research at the Arecibo Observatory, and about our future plans for that research.  We are disappointed that there would be any perception that our activities are somehow deleterious to the environment, or any perception that our research is part of a secret military mission. In fact, we are at the forefront of research to investigate global climate change, research conducted by academic researchers and published in the open scientific literature.  There is no secret or classified research done at the Arecibo Observatory.

 

The Arecibo Observatory has contributed immeasurably to human understanding of our atmospheric environment, to human ability to operate in space, and to the development of modern navigation and communication systems.  We know the people of Puerto Rico and our community neighbors in Arecibo share those accomplishments as a matter of great pride.  It is for this reason that we seek to make our mission and our achievements even more widely known and appreciated.

 

We believe that the concerns of a vocal minority result from a simple absence of information and facts.  For that reason, I attach here a simple list of facts related to our use of radar and to our atmospheric research.  I am glad to meet directly with any group of concerned citizens on these matters who wish further clarification of our research efforts.

 

Sincerely,

 

 

Robert B. Kerr

Director, Arecibo Observatory

 

 

 

 

 

Basic facts about the use of RADAR and

Atmospheric Research at Arecibo Observatory:

 

1. Arecibo Observatory does not perform, and has never performed, classified research. All research at the Arecibo Observatory is public domain, and open to public scrutiny.

 

2. The ionosphere is a naturally occurring region of the atmosphere containing free ions and electrons. The region begins roughly 50 km above the earth’s surface, and extends to thousands of kilometers in altitude.  Much of what we know about this region is due to basic research done at the Arecibo Observatory.

 

3. Arecibo Observatory has performed basic research on the ionosphere since the Observatory opened, in 1963.  This basic research is primarily done using radio frequency (RF) transmission and sampling of the back-scattered signal.  The research has contributed significantly to improved communication and navigation systems for mankind - facilitating modern transportation, safe and reliable human activity in space, and saving countless lives.

 

4. Arecibo Observatory operates two high power RF transmitters on a sporadic basis, less than 15% of the year.  For ionospheric studies, a 430 Mega-Hertz (MHz) transmitter, a pulsed radar with a 2.5 Mega-Watt (MW) peak power capability, is used. Operating on maximum 6% duty cycle, the average power is 150 Kilo-Watts (KW).  A 2,380 MHz transmitter is operated for the Planetary Astronomy program. This transmitter has a 1 MW maximum output power.  This is approximately the same power as is transmitted by televisions stations in Puerto Rico.

 

5. The Observatory transmitters operate in a radio frequency environment shared by many other users. These include radio and television transmissions, cellular phone transmissions, citizens band and “HAM” radio operations, microwave oven emissions, satellite transmissions, and more.  In many cases these RF transmissions are directed at, and intended for, public intercept and use.  Conversely, the Observatory transmitters are directed to space, never more than 20 degrees from the vertical.  Arecibo Observatory participates in good faith with the Puerto Rico Coordination Zone, which coordinates the many users of RF in Puerto Rico.

 

6. The RF environment in an around Arecibo Observatory was tested by an independent contractor in late 2003 and early 2004.  That study compared measured RF levels with the strict FCC guidelines for the “Maximum Permissible Exposure of the General Population/Uncontrolled exposure” (MPE) established in 1997. That study concluded that RF levels at the edge of the telescope reflector and at the Visitor Center observation deck are too low to be measured for all transmit directions, except when the transmission is directed in the exact azimuth of the Visitor Center and in the maximum off-vertical angle.  That particular orientation is not an operational option when the Visitor Center is open.  On the main road inside the Observatory, and outside the Observatory, RF levels were less than 1/100 MPE, the lowest value measurable, and, the study concluded, “below the typical field levels found in many urban environments.”  The Arecibo Observatory radio transmissions do not interfere with other radio users, nor do they represent any health threat to the public or to employees.  Proof of these statements is available for public scrutiny.

 

7. A new transmitter being installed at Arecibo Observatory is intended to permit direct interaction with the ionosphere. The project is funded by the NSF and the DOD. The project is not secret, not classified, and is open to public scrutiny. These active experiments, ongoing at many sites world-wide since 1933, transmit a RF signal that can alter conditions in a very small slice of the local ionosphere for short periods of time.  Because one condition that can be altered is the motion of free electrons in the ionosphere, these experiments are sometimes termed “ionospheric heating”.  This is an unfortunate misnomer.  The enhanced electron motions caused by these experiments are entirely negligible relative to the massive heating of the ionosphere that takes place every day, world-wide – by the sun. 

 

8. In no way do the ionospheric interaction experiments performed at Arecibo Observatory contribute to global warming. This is true because the atmospheric density in the ionosphere is 13 orders of magnitude smaller than at the earth surface, because the enhanced electron motions occur over such limited areas and times, and because electrons are orders of magnitude lighter than ionospheric atoms and molecules – losing their enhanced motions immediately upon collision. In fact, the enhanced electron motions driven by Observatory transmitters are comparable, in terms of thermal impact on the atmosphere, to rubbing your hands together to generate heat. These experiments tell us HOW heat is created and transferred in the ionosphere, but they do not heat the global or regional ionosphere.

 

9. The purpose of the ionospheric interaction experiments at Arecibo Observatory is to understand plasma (neutral and ionized gas) environments.  There are many reasons, from automobile spark plug performance to understanding solar storms, that this basic research is beneficial to mankind.  The DOD interest in this research arises primarily from the need for reliable communication – and that interest is neither secret nor classified.

 

10. The Arecibo Observatory stands at the forefront of global change research in the upper atmosphere.  It is recognized that the largest temperature and composition changes due to global warming will be evident in the upper atmosphere (above 100 km).  Today, Observatory researchers are actively monitoring long-term changes in hydrogen composition, temperature, and wind-fields in the upper atmosphere, in order to quantify global change and thereby improve our understanding of the global climate change process.  This is mainstream environmental research, and the people of Puerto Rico are justified in their pride at being on “the forefront” of this research that is important to all of humanity.

 

11. One secondary benefit of the research transmitters at the Arecibo Observatory has been their use to monitor the potential environmental impact of asteroids (or comets) that threaten to collide with the Earth.  Arecibo Observatory serves as a sentinel for these events, and the use of our transmitters for this work places Puerto Rico in a leading position in terms of environmental service to the entire planet.

 

12. Arecibo Observatory participates as a contributing member of the Joint Institute for Caribbean Climate Studies (JICCS), a consortium centered at UPR-Mayaguez studying climate change and its impact on Puerto Rico and on the Caribbean region.

 

13. The current site director at Arecibo Observatory is a dues-paying member of Green Peace International – a well known environmental steward.  In no way are the citizens of Puerto Rico being used as objects for potentially destructive environmental or military purposes by the Arecibo Observatory.  The facts are entirely the contrary; the Arecibo community is at the forefront of efforts to understand global effects on the environment.  We appreciate the support of the people of Puerto Rico in carrying out this important mission.