Introduction
T-22 is a building with two 60 foot dish antennas located on the northern most edge of the mesa north of Boulder, Colorado. The site is part of the current Department of Commerce, Institute for Telecommunication Services (ITS), In 1990 a group of people received permission, from then the National Bureau of Standards, to work on the facility. When we arrived at T-22 it was an abandoned, rat infested building full of racks of vacuum
tube equipment. We have made many improvements to the building itself
as well as the dishes and control systems.
Building
We started by doing some extensive cleanup and repair of the
building to make it a place where humans could work. We then painted
the whole interior and erected a wall between the control area and a
general work/meeting area. The building could only be easily used in
warmer weather since we had no practical way to heat it and prevent
pipes from freezing. Water had to be shut off and drained in the
winter. We rebuilt the water pump, replaced the hot water heater,
installed a propane furnace, replaced the toilet as well as adding
heat tape to the pipes to make this a usable building. At first the
power bill was paid for by others (I think it was NOAA). When that
stopped we found that we could not afford commercial three phase
power. We had the power converted to single phase and were able to
obtain a 30kw three phase diesel generator from CU that we wired into
the towers to run the three phase motors. This was used until we
upgraded the motor drive system to a much more efficient single phase
variable frequency drive system.
The towers themselves were the object of vandalism in the early
years. Each time we installed locks they were broken. We finally
ended that by installing very expensive padlocks to the doors of both
towers. The scaffold for the lower dish, long gone, was rebuilt to
make that dish usable.
Dish drive system
Around 1991 we assessed the drive system
and quickly realized that extensive motor repair work was needed
before we could even attempt to move the dishes. We undertook the
difficult task of detaching and lowering these extremely heavy motors
along with their eddy current clutches to the ground so we could
work on them. All motors were rebuilt and repaired and reinstalled in
working order. The dish gears and elevation screws were inspected and
lubricated before movement was attempted. When all of the repairs
were completed we successfully moved the upper dish. Early on, most
of our efforts were aimed at the upper dish. Only when that was in
reasonable shape did we turn our efforts to the lower dish some years
later. That is now usable as well.
The original drive systems were not very suitable for tracking
celestial objects, or much of anything else or that matter. Eddy
current clutches do not provide very precise control over the dish
speed and do not allow for slow movement. After several years we were
able to obtain two variable frequency drives and appropriate motors.
We installed those and were able to make them operate well, within
their limitations.
After several years of use we started to have problems with the
very large bolts that hold the Azimuth gearbox breaking. This
resulted in the azimuth drive shaft breaking. Repairing this was a
multi year effort that including custom machining new bolts and a new
drive shaft. It has worked well ever since.
Dish RF systems
The dishes had very old, deteriorated Heliax cables and a feed
point mount that was difficult to use. We designed a feed point
mount that can easily accept different feed point antennas. We also
undertook the difficult task of replacing the Heliax. This involved
threading this cable up the center of the tower, into the bottom of
the dish, attaching it to one of the tripod legs and terminating it
at the feed point.
Numerous feed point antennas have been built over the years.
Crossed dipoles, horns, helix's and patch antennas have been used at
a variety of frequencies.
Projects
We have done several major projects with other groups over the
years. The most significant ones were Falcon Gold with the Air force
Academy and Paratrak with CU computer science students.
Falcon Gold was the Air force Academy's first student (cadet)
designed and built satellite. They realized that they did not have a
ground station with sufficient gain to receive the signal from the
satellite and came to DSES for help. We provided them with a ground
station that tracked the satellite and received its telemetry. This
was a multi-month project during which we worked closely with the
officers and cadets to help them achieve their goals. It was a great
success.
The Paratrak project was a senior project for a group of CU
computer science students. DSES built a closed loop controller and
provided a software driver for the students to use. They in turn
designed the software to drive the dish. The program accepted
tracking instructions in several forms including RA and DEC, TLEs (
two line elements) as well as a pull down menu of celestial objects.
It was basically a good project but did not provide the accuracy that
was required for all of our needs. It is in the process of being
replaced with a new system that is currently being designed by an CU
aerospace engineering student as a formal project.
We have provided a number of school groups with exciting and
educational tours. This has encouraged several of them to pursue
physics and engineering when then entered college.
History SummaryThe Deep-Space Exploration Society (DSES) was incorporated in 1991 and was the outgrowth of an effort to return the Table Mountain antenna facility in Boulder County to active use after many years of dormancy.
DSES operated the radio dishes on Table Mountain under a Cooperative Research Agreement with the National Telecommunications and Information Administration, Institute for Telecommunication Sciences authorized under the Federal Technology Transfer Act of 1986.
As the systems were upgraded and made operational other projects became possible. An early spinoff of these efforts became the Edge of Space Sciences (EOSS) nonprofit group, which launches high altitude research balloons. At the time, DSES tracked and recovered data for about 50% of their launches. We supported at various times the Mars Global Relay mission, the Air Force Academy Falcon Gold Satellite mission and others.
DSES also seeks to involve students in the use and continuing development of the site. Students from a University of Colorado engineering class developed a tracking and control program for the facility known as Paratrack.
With the ability to use two dish antennas we begun utilizing a dish in a drift scan mode to acquire data from cosmic radio sources. This was done to test and calibrate some newly acquired radio astronomy equipment. This is expected to be an ongoing project in amateur radio astronomy research and education. About 50% of our group’s volunteer time goes into continuing maintenance and upgrading of facilities and equipment.
In 2010, with the acquisition of the Paul Plishner Radio Astronomy and Space Science Center, we left the Boulder County Table Mesa site with its two 60ft dish antennas. Now, even though we only have one dish antenna, many more opportunities to work with the education and science centers have become possible. Future plans include a system for making real time data from the antenna available on the internet and later the capability to allow remote command and control of the antenna from the internet. This will provide a convenient way for DSES members to monitor their projects remotely and thereby expand the utilization of the facility. In time it may also become possible for outside researchers and groups to remotly operate the facility as a research tool for their own projects.