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SETI
- Allen Telescope Array
- Optical SETI
- Interstellar Message Construction
- Project Phoenix 1995-2004
- Background Science
- History of SETI
- Center for SETI Research Team
- Other people doing SETI
- Hollywood's View of SETI
Past Observing Campaigns
Green Bank, West Virginia
Observing Run: January 22 - February 10, 1998
January 29, 19:00 UT Mountain View, CA
Starting observations has gone fairly smoothly for the last few runs. In anticipation of a smooth start-up, I brought along two books, a mystery and an introduction to Java. I should have known better. Murphy had been away too long.
The physical installation of the receiver was finished quickly on the morning of the 22nd. However, we couldn't reliably command and monitor the receiver and down converter, suggesting a problem with the optical fibers. Green Bank engineers and techs che cked and cleaned the fiber ends and connectors. We also found a module of software that needed to be restarted. Eventually, when communication with the receiver was established, were able to determine that the oscillators in the downconverter would not locked to the frequency standard. After a day of trouble shooting, including trying an alternate standard, the problem was traced to a bad capacitor in a power supply in the reference signal distribution amplifier.
On the 23rd, we were ready to observe. NOT! First, a circuit card had to be replaced in the telescope declination drive controller. Then, the telescope software interface wasn't able to read the position of the telescope. It turned out that one piece of software in the interface (which involves four computers) had a hard-coded year of 1997. (A variant of the millennium bug?) Finally at 2:30 PM EST, we were ready to observe Pioneer 6 and test the system. Unfortunately, Pioneer 6 had just gone below the horizon for Woodbury. Fortunately, Pioneer 10 was about to rise. Its signal has become much weaker since we first saw it at Green Bank 15 months ago. After a full nine minute observation, we were able to confirm detectio n of the carrier signal at Green Bank and Woodbury.
SETI Observations began on January 23 at 5:00 PM, 22:00 UT. Nine hours later (around 2:00 AM) a transformer failed, shutting down the air conditioner for the Mobile Research Facility, the portable container for the signal processing equipment. A few mi nutes later, the system automatically shut down the electronics to avoid overheating. Green Bank engineers had the problem fixed before dawn. We were observing again by 7:00 AM, just in time for me to leave for the airport. Before I could get out the d oor, a temperature sensor in one of the electronics racks started giving intermittent false readings. Since it seemed to settle down, I finished packing and left.
I was probably still driving in Pocahontas County when the faulty sensor triggered another shutdown. The Phoenix staff member on duty in California had to bypass the sensor limits. This allowed the system to keep observing until 1:00 PM, when wet, heavy snow forced the operator to take control of the telescope. Although the telescope structure is strong enough to handle the weight, the panels that make up the highly accurate surface can be damaged. So the antenna is pointed at the horizon to keep snow from accumulating on the surface.
Over the next few days observations were interrupted by more bad weather and intermittent problems with the temperature in the cryogenic portion of the receiver. This morning the Green Bank staff replaced a compressor and the receiver temperature seems t o be more stable.
-Peter Backus
February 10, 1300 UT Mountain View, CA
It's been a heck of a run. After the startup problems described above, we lost a total of 70 hours due to weather. The receiver continued to have intermittent temperature problems, but nothing too serious (it will be worked on next week).
In spite of everything, we still managed to cover most of our planned observing at L-Band.
- Peter Backus
February 11, 1700 UT Mountain View, CA
Immediately following the end of SETI observations yesterday, we began an experiment to search for dark galaxies which are gravitationally lensing distant quasars. This program is in cooperation with a number of astronomers from Scotland, France and Japan. It is similar to a successful experiment conducted at the Parkes Observatory in collaboration with Australian colleagues.
In this experiment, we turn off the signal detection computers and simply use the receiver, intermediate frequency electronics, and the spectrum analyzer. The coarse resolution (643 Hz) data from the MCSA are analyzed off line. The wide tunability and performance of the receiver makes it ideal for this type of experiment.
We are looking for radio emission from hydrogen atoms in the galaxy or galaxies that form the gravitational lens that produces multiple image of a distant quasar. The lensing galaxy is so far away that the radio waves from the hydrogen are "redshifted" by the expansion of the universe. While the emission of hydrogen atoms from our galaxy is found near 1420 MHz, the emission from the lens may be shifted to well below 1000 MHz. We're searching the spectrum from 1070 MHz to 1200 MHz, the range available with our receiver. Observations at lower frequencies will use other equipment at Green Bank.
After a few minor problems configuring the system, we started observing around 1400 UT yesterday. The frequency range below 1150 MHz is heavily used by aircraft transponders. Unfortunately, the National Radio Quiet Zone regulations cannot protect Green Bank from high flying transmitters. Some of the frequency bands will be very difficult to process for the weak hydrogen signal from the gravitational lens.
-Peter Backus
Observing Run: March 3 - 26, 1998
March 4, 23:30 UT Mountain View, CA
The first day of observing is always a little busy. There are many tests that must be performed to make sure that all of the equipment is functioning properly and that the telescope is pointing correctly. There are just so many things that can go wrong, and this time a few of them did. First, we couldn't control the receiver and downconverter. The problem turned out to be a bad connection in an optical fiber. Then we couldn't get the test signal injected into the receiver. This was due to a faulty switch in a series of cables. Once they were identified, these low-tech problems were fairly easy to correct. Then as we performed final system tests before observing, one of the spectrum analyzer units started producing bad data. After running diagnostic tests from California, we determined that two circuit boards needed to be replaced. Finally, at about 0400 UT we began observing.
At 1300 UT (8 AM EST) we stopped for the weekly 8.5 hour period of telescope maintenance. Observations resumed immediately following maintenance. We're currently observing a star known to have a planet-sized companion.
- Peter Backus
March 13, 2200 UT Mountain View, CA
Observations are proceeding fairly well. The MCSA circuit boards that apparently failed last week have been undergoing detailed diagnostics in the lab. It turned out that only one board had a problem. Apparently a solder connection had opened up on a clock line termination. This has been repaired and if the board continues to pass diagnostic tests this weekend, it will be returned to the supply of spares in Green Bank.
As of this entry, we have completed observations of 116 stars at all available frequencies. Another 41 stars have been finished at L-Band (1200-1740 MHz).
- Peter Backus
March 23, 2300 UT Mountain View, CA
Besides observing our regular star list, we are finishing observations of positions where the Planetary Society's Project BETA has detected signals that appeared once and were never confirmed. These observations are tuned to a "magic" frequency, i.e., one that would be known to radio astronomers throughout the universe. In this case the frequency is twice the natural radio frequency emitted by un-ionized hydrogen atoms.
Observations have been going well. We did have a problem with the telescope drive hardware. The able staff in Green Bank had the faulty electronics replaced in just 30 minutes.
- Peter Backus
March 26, 2000 UT Mountain View, CA
This observation run ended at 5:00 AM PST this morning. This finishes our allocated time for S-Band observations at the 140 Foot Telescope. We will observe for one week next month at L-Band (1200 - 1750 MHz). Then it's on to Arecibo.
I've updated the plot that summarizes the observations to date.
- Peter Backus
Observing Run: April 24 - 30, 1998
This short run marks the end of our observing program at the 140 Foot Telescope. This time was allocated to Project Phoenix to make up for time lost in previous runs due to telescope equipment problems. It was an "eventful" run. We managed to accomplish most of the intended observations in spite of a number of problems. Rather than just posting the usual observing reports, I've excerpted reports from some of the internal project email that gives a feeling for how we sometimes have to cooperate between several locations to solve problems.
I want to emphasize that we accomplished a great deal of observing during this week. This just shows what sometimes goes on behind the scenes.
- Peter Backus
April 24, Green Bank
The receiver went onto telescope fairly quickly, but we could not establish communication with it. Using power meter and reflectometer, the crew determined that the "yellow" optical fiber was bad. (It actually felt damaged near the connector.) One of the spare fibers was swapped in. This established communication for monitor and control, but we were unable to see the test signal. This was result of a cryogenic switch being stuck in the S-band position. Cycling the switch by submitting S-band and L-band command files got it working again.
Standard startup tests did not produce a detection of the test signal at Woodbury. After quite a bit of testing, we ascertained that the frequency tunings being requested at Woodbury were bogus. We decided to begin one-site observations while we investigated this problem.
- Jill Tarter
25 April, Green Bank
Ran in one-site mode through the night. In the morning we ran system tests using the signal from Pioneer 6. It was detected in the first three observations. Fortunately a film crew was here so we continued to observe the spacecraft so they could film the computer screens. I say "fortunately" because we failed to detect the spacecraft in these extra observations. This indicates that we have an intermittent problem (the worst kind) at Woodbury.
We will continue in one-site mode while we investigate the the frequency settings at Woodbury. We also noticed another bug in extended Pioneer 6 observations. The position of the spacecraft is recalculated at the beginning of each observation, but only sent to Woodbury during the first observation. This is a minor bug, not affecting observations of stars. Even for P6 it would only cause problems when observing this spacecraft for extended periods of time, i.e., much longer than our typical daily P6 observations that last about 15 minutes.
- Jill Tarter
26 April, 1400 UT, Mountain View
Finished a twelve hour run on the Gravitational Lens candidates. Things went smoothly most of the night. There were two cases where interference (aircraft DME transponders?) overwhelmed the MCSA causing a reload of microcode. One more lens candidate to observe on Tuesday.
Ran a series of observations on Pioneer 6. Detected on remote FUDD B but not on FUDD A.
- Peter Backus
26 April, 2100 UT, Berkeley
Well, the gremlins seem to be working overtime in Woodbury. The test signal disappeared due to a problem in the 0 - 11 dB attenuator used in adjusting the strength of the signal. Workaround: don't command the test tone signal to noise ratio to be exactly a multiple of 10 dB.
In tracking this down I found two software bugs that can cause the test signal to be tuned incorrectly under certain (rare) conditions.
Then we found that LO#3 for FUDD A at Woodbury was not being set. It apparently "forgot" its HPIB address. Doing a manual restore and reprogramming the address seems to have cleared up the problem. This was the reason that Pioneer 6 was only seen by FUDD B.
- John Dreher
27 April, 2000 UT, Woodbury
I believe that I have found the source of the current WB difficulties, the 5 MHz reference cable has crimped and broken through the twister. The intermittancies were probably caused by an intermittant connection as the twister rotated. In the near term we could reroute the reference signal through the test tone RF cable (they are identical) and do without the test tone. We were able to find this by the fortuitous chance that the particular azimuth we are currently at allowed access to the section of cable.
We are checking the other cable runs through the twister as best as we can (it is not very accessible).
Let me know but I suggest we reroute the cable and then check the system out with P6/P10 and go from there.
- Dave DeBoer
30 April, 2000 UT, Mountain View
Observations finished early this morning (5:00 AM California time). We've just finished having a meeting to discuss final details for the move to Arecibo and Jodrell Bank. We expect the MRF to arrive at Arecibo Observatory in the first week of June. The downconverter, FUDDs, and control computers will arrive in Jodrell later.
1 May, 1500 UT, Green Bank
At 16:30 yesterday (4/30/98) the Air conditioner blew the same fuse it has been blowing several times in the past few weeks. I think (time will tell) the cause was not the new transformer I had been suspecting. (This transformer was the spare to first that failed apparently from a manufacturing defect.) It was a solenoid operated valve, the valve which controls the hot gas bypass. This valve operates whenever the temperature reaches the lower set point and thereby prevents further cooling action. The reason why it was blowing fuses was that its plunger had become gunked up with a sticky residue that prevented the plunger from rapidly sucking home. I think the sticky substance was coil potting compound that had leaked its way into the plunger cylinder. AC solenoids are designed so that magnetic circuit is only made up when the plunger is fully retracted. This is intended to permit large initial currents to flow thus accelerating solenoid action and partially compensating for poor initial magnetic efficiency. When the retraction time is slowed, by the sticky stuff, these large currents can persist over a much larger time scale than the design intended. That apparently was what was happening. Since can be a variable phenomenon, it also would explain why it did not blow the fuse every time the air conditioner cycled.
Credit should go to the (NRAO) electricians Carl and Rusty who came in after hours to help me. Unbeknownst to me, Carl had spent the afternoon monitoring the current through the fuse and noted that there was a correlation between between operation of this valve and a current surge through the fuse. So when they came back after the fuse had blown, he brought a replacement solenoid coil with him. (They are pretty standard.) After he changed it out, we waited around for half an hour or so until the temperature in the MRF reached the set point and started cycling. So far, the fuse is holding in there.
I intend to have ATS check all the solenoid valves when they go through their factory service.
- Bud Hill
May 4, Mountain View
The MRF has been powered down to avoid more problems with the air conditioner. Several Phoenix staff members are on their way to Green Bank and Woodbury to pack things up for shipment to Arecibo and Jodrell bank. The MRF will make a planned detour to the air conditioner manufacturer in Maryland for servicing.
Since the up-to-date database is on a computer in the MRF, and the backup tapes haven't arrived yet, I've compiled a brief summary of the observations from our final run using log files.
| Star | Frequency Range |
| 1010 | 1200 1740 |
| 3207 | 1200 1740 |
| 4062 | 1200 1740 |
| 4064 | 1200 1740 |
| 4065 | 1200 1740 |
| 4067 | 1200 1740 |
| 4070 | 1612 1650 |
| 4074 | 1200 1650 |
| 4109 | 1200 1370 |
| 4119 | 1630 1740 |
| 4121 | 1630 1740 |
| 4153 | 1200 1740 |
| 4154 | 1650 1740 |
| 4159 | 1200 1590 |
| 4168 | 1200 1450 |
| 4180 | 1612 1640 |
| 4319 | 1200 1250 |
| 4467 | 1200 1740 |
| 4794 | 1200 1740 |
| 4985 | 1320 1640 |
| 5017 | 1612 1640 |
| 5108 | 1200 1740 |
| 5297 | 1200 1250 |
| 5365 | 1220 1290 |
| 5623 | 1200 1230 |
| 5634 | 1200 1230 |
Some of these stars are not on the original list. We expanded the list to additional stars as new data became available from the Hipparcos satellite. This gives the automatic scheduling program more flexibility.
We also observed four areas of sky centered on the positions reported by the Planetary Society's Project META as locations of possible signals. Nothing was found in spite of our significantly higher sensitivity.
- Peter Backus