Green Bank Observatory Trips

Green Bank Observatory Picture from Google Earth

In a narrow vale between two folds of earthen ridges in eastern West Virginia, a man-made structure stands nearly 150 meters tall. This is the Green Bank radio telescope, a unique resource that is the largest fully steerable radio telescope in the world, with an antenna 100 meters in diameter. The radio telescope is at the heart of what was once called the National Radio Astronomy Observatory, and is now run by the Green Bank Observatory. The facility is in the middle of a radio-free zone, where cell phones go to die, since there is zero cell service in this region.

The facilities at this observatory are not just for the use of professional scientists. There is a 40′ radio telescope that is available for use by school groups to learn the principles of radio astronomy, and the principles of scientific observation. I was fortunate enough to chaperone two groups of high school seniors from South Charleston High School (SCHS) on their overnight excursions to this wonderful resource. The International Baccalaureate Physics teacher at SCHS, Janet Richardson, arranged for this field trip annually. I went in the years that my sons were in her physics class.

When we reached the observatory, we had a lecture from one of the observatory staff who explained what we were going to be looking for. The 40′ telescope is now fixed in place, so it allows observations of what is directly overhead as the earth rotates. This means that you can see the galaxy rotating towards you for one part of the day, and you can see the galaxy moving away from you 12 hours later. If you have a radio telescope tuned to the correct wavelength, you can observe the emissions from hydrogen gas found in our galaxy. If you remember the Doppler effect from physics, and you think about train whistles, you will remember that as the train is coming towards you, the pitch is higher. Then when the train passes you, the pitch lowers. That is the same phenomena that the radio telescope is observing. As the hydrogen gas in the galaxy moves towards you, the frequency moves up – the signal is shifted towards the blue end of the spectrum. If the gas is moving away, the signal shifts towards the red. By taking measurements around the clock, you can see the rotation of the galaxy as measured from our position on one of the outer arms of the galaxy.

The 40′ radio telescope is one of the first telescopes within the quiet zone of the observatory. Once you enter the quiet zone, there are no powered vehicles except for old diesels. Spark plugs are capable of creating intense interference for the radio telescopes, so you see Checker cabs from the 1940’s and 1950’s available to transport people. There are some diesel vans as well that are used to move the students back and forth. You enter the quiet zone after passing by the start of the scale model of the solar system, with the inner planets grouped closely together. Then a significant gap, and finally the symbol for Jupiter appears on the side of the road. The gaps between the planets grows, and we reach our destination for observation halfway between Uranus and Neptune. The building that accompanies the 40′ scope is small above ground. Once you enter the door, you descend a short flight of stairs to come to the observation room. This is a scientific instrument history display, but all of the analog dials and gauges and chart recorders are still working. I probably used similar chart recorders back in my college days in the 1970’s.

green bank solar system model

The room where the measurements are taken has been used by various school groups for decades. Mementos of these groups can be found scrawled on the ceiling beams, and the wall beams, where you can see which colleges, and which high schools left their mark for future students to see. The students have been instructed on how to tune the receiver to the correct frequency bandwidth, to start the chart recorder, and to begin their observational period. They move the frequency detector manually through that range, and the chart recorder shows the response. Hydrogen gas, if it is not moving relative to the observer, will emit radiation at 1420 mHz. If it is moving towards the observer, the frequency will increase, and if moving away, the frequency will decrease. As they step through the frequency range, all of a sudden the antenna picks up the signal from hydrogen, and the chart pen goes up. The height of the response is proportional to the concentration of hydrogen being observed. The students move the frequency through the entire assigned range, and the pen comes back down to the baseline. Thus completes one set of measurements. Each group of students makes two observations over the course of their stay.

The first year I went, Janet asked me to stay with the students through all of the late night observation shifts. So while each student only got to see one measurement in the middle of the night, I got to see multiple hours of observation, and really got the sense of seeing the motion of the galaxy in real time. But once the last group of students took their measurements, I was ready to go back to the bunkhouse where the boys in the group were sleeping. The accommodations are not spartan, but the dual rows of bunk beds do not allow for any privacy. They do enable a bit of mischief, like the spray cheese some of the boys put on the hand of another sleeping student, ensuring that when they tickled his face, he would smear the cheese all over his face. I, being a sound sleeper, heard none of this mild mischief.

On my second trip to the observatory, we saw the place where conspiracy theorists (the tinfoil hat crowd) would love. We got to go inside of a room-sized Faraday cage. A Faraday cage is an enclosure that does not permit electromagnetic radiation of certain frequencies to enter or leave. This is where the computer equipment is for the observatory. Since the antennas are so sensitive to stray radiation, the computers have to be totally shielded away from the antennas. The walls, ceiling, and floor are all impregnated with a copper mesh. There are holes in the mesh, because they are only concerned with blocking radiation of certain wavelengths and the size of the holes in the mesh govern the size of waves that can escape.

For this middle-aged self-admitted science and astronomy nerd, the two days off work that I took for these trips were some of the better vacation days I ever spent. It’s now been 10 years since my older son took his trip. I asked both my sons about what they remembered, but it seems that the details of the science portion has been lost to the vagaries of time. I asked Janet what she had the class do with their measurements once they returned to the classroom, and she said that their task was to get an image of the galaxy by looking at their observations over the course of a day. I cannot express my appreciation to teachers like Janet Richardson, who help to ignite the spark of curiosity in classes of young men and women. She said that in the future, they may get involved in the programs that they have to discover pulsars. It’s a crowd-sourced project, where the data from observations are available, and interested volunteers can use their computers and software from the observatory to try to detect pulsars that have not yet been identified.

I noted at the first of this post that the observatory used to be known as the National Radio Astronomy Observatory. It was funded by the National Science Foundation (NSF). As part of the ongoing disinvestment in science that began years ago, the NSF no longer provides 95% of the funds for the facility. Up until late in 2017, it was even feasible that the NSF would call for the demolition of the telescope. But since that time, a compromise was reached that enabled the observatory to stand as a self-sustaining organization. The Green Bank Observatory now is partnering with universities, like West Virginia University, and is involved with several multi-year projects including Project Breakthrough Listen, which is surveying the million closest stars to us and looking for signs of intelligent life. But like all such facilities, the needs for funds continues. If you would like to support the science programs of this unique facility that seeks to expand our knowledge of our origins, here’s the link to get involved:

Gold Fever


Carl Sagan famously said “We are made of starstuff.” That is, the elements of life, the carbon, oxygen, nitrogen, phosphorus, iron, sulfur, and of course hydrogen, all come from the life processes of normal stars. Through fusion, there is a progression in the atoms that are forged within stars. Hydrogen begets helium, and later on in a star’s life, helium begets carbon, nitrogen and oxygen. Further fusion reactions occur within a star’s core, releasing energy until iron predominates at the core of the star, where the fusion reactions proceed. Iron, though, represents a dead end in the fusion process. Iron cannot undergo a fusion reaction that creates more energy than it takes to react. So the swollen mass of the red giant star that was inflated by the energy released from fusion reactions, suddenly collapses upon itself. The in-falling matter creates critical masses in the outer layers of the star, exploding in a new pressure wave that expels the outer shells of the star. Thus, a typical nova occurs in a galaxy far, far away (even novas in this galaxy are far, far away).

A typical nova (or even a supernova) does not have the capability to create the large number of high atomic weight elements like gold, or uranium, or platinum. To create these elements, it takes an even more spectacular event. One such event, the spiraling collision of two neutron stars, was observed on August 17, and three separate types of instruments observed the event. First, the new gravity wave detectors in Louisiana and Washington state, and one in Italy, picked up the signal of gravitational waves rippling through space. This was followed within seconds by the detection of high energy gamma rays by the NASA Fermi space telescope. Then, with the directional information available from these instruments, optical telescopes were able to pick up the visible light emanating from the collision of two neutron stars, creating nuclear synthesis of myriads of elements in a blaze of electromagnetic radiation.

For those who are not familiar with astrophysics, neutron stars are the remnants of a certain type of supernova that lost their outer shells in an explosion, and contracted into small balls of condensed neutrons. Imagine a star about 1.5 times the mass of our sun, but contracted into a sphere about 12 miles in diameter. The density of this material is incredible. A cubic centimeter (about the size of a sugar cube) would weigh 100 million tons on Earth. Neutron stars are not black holes, though. They emit both light and radio waves. In fact, the first neutron stars were detected because they rotate incredibly fast. Slow ones rotate in little more than a second, while fast ones rotate hundreds of times per second. They can be detected by the radio waves they send out with each vibration. These types of rotating neutron stars are called pulsars.

So two of these neutron stars began a death dance spiral 130 million years ago on August 17. They spin together, faster and faster, until they actually collide, and then all hell breaks loose. Megatons of gold, platinum, uranium, and all of the heavy elements are formed from the intense bombardment of neutrons. These atoms form, cool, undergo nuclear reactions and form more stable isotopes that stream out into space. All of this matter spreads out, and settle inside of gas and dust clouds where gravity attracts them. Eventually, the gas cloud gains enough mass to start to collapse into itself, and a solar system with a new star emerges. The heavy elements from the neutron star collision are incorporated into the new planets. If there are enough of these elements in the gas cloud, and if intelligent life evolves on one of the planets, they discover these elements, and perhaps fashion them into rings, or necklaces, or fission bombs.

The detectors of the gravity waves are magnificent structures that bear homage to science and to the spirit of the countries that devoted resources to these instruments. Within the US there are two LIGO (Laser Interferometer Gravitational-Wave Observatory) facilities. These facilities are situated thousands of miles apart, in order to eliminate any local vibrations from giving false signals. They are L-shaped structures, and the lengths of the arms is 4 kilometers per side. The core of the instrument is a vacuum tube, with lasers and mirrors situated inside to cause a laser beam to split and bounce back and forth for hundreds of times before it is sent to the detector.

Normally, laser beams that are split in two and then travel identical path lengths, and then recombined can be positioned so that the beams interfere with each other perfectly, and no light is detected by an instrument at the end of the beam path. But if something affects the length of the path of one of the beams, then the total path length of the two split beams is not the same. When that happens, the photodetector sees a beam. The beam that is detected is affected by the difference in distance between the two paths. Gravity waves cause the length of the path to differ slightly and as the wave sweeps over the two detector beams, first one beam moves with the wave, then the second beam moves. How much is the movement that is detected? One ten thousandth of the width of a proton is the amount of displacement that is caused by a gravity wave.

Since there are now 3 gravitational wave observatories located in different parts of the globe, each observatory detects gravity waves at slightly different times. By comparing the time differences between the signals, scientists are able to triangulate and determine where in the sky did the cosmic event happen. Scientists had detected the merger of two black holes several times with the LIGO detectors, but the events of August 2017 was the first time that they were able to see an event occur in the electromagnetic spectrum as well.

At this time of year, you will see many ads extolling the virtues of giving a gift of gold. If you do buy a gift of gold or platinum for someone, take a moment to realize that the metal you are buying was formed in a cataclysmic collision billions of years ago, before our sun and planet were born. And marvel that we now have the ability to detect and understand our universe and the wondrous events that shaped our world.