"New South Polar Times Report"
Mike Masterman - July 12, 1995
Currently at the South Pole, work is under way to establish an Observatory to look at galaxies and other various clumps of matter within the universe. One of the specific projects assigned to do this task is the Cosmic Microwave Background Radiation (C.M.B.R) project. My name is Mike Masterman and I am the winter over engineer for this project.
Due to the severity of the conditions at South Pole, a telescope is currently being developed to withstand some of the worst weather conditions in the world. The first telescope that was designed for this application was able to withstand the summertime weather conditions, but once the temperatures dropped down below -95 degrees Fahrenheit, the telescope became non-operational.
It is my job this winter to analyze where the failures are occurring in order to design a second generation telescope that will survive the wintertime operations. The sight where I work is located one kilometer (.6 miles) from the dome where we all live. The buildings and telescopes are placed that distance away from the station in an attempt to avoid interference caused from station radios and electrical appliances.
There are several items that must be dealt with differently when designing a telescope to operate in these temperatures. One of the most difficult problems is to allow everything to be accessible for an individual wearing a huge parka, mittens, and lots of other clothes. In order to make it easier to access in cold weather gear everything must be designed as large as possible.
Not only must equipment be designed to withstand the cold, there are several other hardships that must be considered. The first one, the one that has probably taken out more electrical equipment than any other thing, is static electricity. The South Pole is one of the driest places in the world. Between the dryness and the cold, static electricity is always present. This makes sensitive electronics (like CMOS digital logic) very impractical. Not only must the proper components be used to prevent damage, but all enclosures must be grounded to a quality ground. Thousands of dollars worth of equipment have been lost to static electricity down here.
The power supplied to our electrical systems is generated down here. A power plant located back around the dome supplies us with three phases of 120 volts. This power is in high demand; the cold weather causes very high draw situations. This power overload can cause large spikes of power or supply low voltage for a brief period of time. All electronics for these systems down here must be designed with this irregular power supply in mind.
The Telescope receiver system: The telescope uses the latest receiver technology using special cryogenic HEMT Amplifiers. This receiver operates at a wavelength of 7mm, or at a frequency of 38 to 45 GHz.
HEMT amplifiers use a High Electron Mobility Transistor that operates at a physical temperature of 15 Kelvin. It is very difficult to cool the receivers down to these temperatures. A closed cycle helium four system is used. We have had a great deal of trouble with the lines that carry the helium from the compressor to the refrigerator head. These lines are sealed with rubber o-rings and the o-rings freeze solid at these low temperatures, thus allowing the helium to leak out. Several attempts have been made in heating these joints but it has been determined that the best method to seal these joints will have to be a metal to metal contact.
The Dewar package must also be heated. The Dewar package is what houses the cryogenic equipment and refrigerator head. We must have an airtight seal with this dewar so that a vacuum may be maintained while the system is in operation. In order to keep this vacuum we must not allow the o-rings to freeze; this is why we must heat the outside of the dewar and cool the inside.
The particular receiver to be used will work in broad band detection, supplying us with a voltage proportional to the input power. This voltage is to be taken to the analysis stage which is accomplished via computers.
Planned Observations: This new telescope is being prepared to study the Cosmic Microwave Background. The cosmic microwave background is the debris found at the ends of the universe which is believed to be established by the big bang at the beginning of the Universe. This matter puts out approximately 2.7 Kelvin of radiation but this amount of radiation varies slightly. The variation of the power output should give us some indication of how the universe was formed and the evolutionary process that it went through to get to the current state.
|Back to Field Journals Menu||New South Polar Times Report 1|