dipper@utastro.UUCP (Debbie Byrd) (03/07/85)
Astronomers are listening with radio telescopes for signs of extraterrestrial civilizations. More -- after this. March 7 Project Sentinel's Anniversary Today is the second anniversary of an ambitious project to look for other intelligent life in the universe. Project Sentinel -- funded by the Planetary Society -- is searching specific radio frequencies that might be in use as interstellar communication channels. There are a vast number of such possible channels. Astronomers have tried to narrow down their listening choices to certain plausible radio frequencies -- ones that would be recognized and might be selected by any technologically advanced species. One such universal channel is the radiation frequency of neutral hydrogen atoms -- since hydrogen is the simplest and most abundant element in the universe. Still, even if we pick and choose, there's an enormous range of signals to check. In 1983 Project Sentinel brought Harvard University's 84-foot radio telescope out of retirement -- and put it to work listening continuously -- day and night -- for possible radio emissions from other civilizations. A frequency analyzer divides the information collected from the radio telescope into one hundred and twenty-eight thousand separate bands -- and each band is checked for strong or unusual electronic patterns that could be carriers of interstellar communication. This year Project Sentinel astronomers plan to expand its monitoring capacity to eight million channels. So far we've heard nothing from another civilization. If there are other advanced lifeforms -- then perhaps we haven't tuned in at the right time on the right channel in the right direction in space -- yet. Script by Diana Hadley. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
crs@lanl.ARPA (03/08/85)
> Astronomers are listening with radio telescopes for signs of > extraterrestrial civilizations. More -- after this. > > March 7 Project Sentinel's Anniversary > > Today is the second anniversary of an ambitious project to look for > other intelligent life in the universe. Project Sentinel -- funded by > the Planetary Society -- is searching specific radio frequencies that > might be in use as interstellar communication channels. > > There are a vast number of such possible channels. Astronomers have > tried to narrow down their listening choices to certain plausible radio > frequencies -- ones that would be recognized and might be selected by > any technologically advanced species. One such universal channel is > the radiation frequency of neutral hydrogen atoms -- since hydrogen is > the simplest and most abundant element in the universe. Still, even if > we pick and choose, there's an enormous range of signals to check. > Is it safe to assume that what they hope to receive is a "probe" from some being that is also looking for other intelligent life? I ask because it occurs to me that frequencies such as "the radiation frequency of neutral hydrogen atoms", while attractive as a physical constant, seem to me to be as unlikely for use in everday communications by an "extra-terrestrial" as they are here on earth. Radio communication here on earth began with those frequencies that could be easily generated with frequency bands being added as technology progressed. Can anyone clarify the reasons for the frequencies chosen and, perhaps, list the bands of interest? Are "we" listening to any mundane frequencies such as those of the various broadcast bands? Perhaps they too have a Babel of rock stations! Charlie
sunny@sun.uucp (Ms. Sunny Kirsten) (03/08/85)
> Astronomers are listening with radio telescopes for signs of > extraterrestrial civilizations. > So far we've heard nothing from another civilization. If there are > other advanced lifeforms -- then perhaps we haven't tuned in at the > right time on the right channel in the right direction in space -- > yet. Perhaps the more advanced civilizations use PSI (ESP) for communication, rather than electromagnetic radiation. Why would they use a frequency of Hydrogen when there's so much background noise in the universe at those frequencies? Oh, I get it, they're probably modulating the radiation from one of their stars? -- {ucbvax,decvax,ihnp4}!sun!sunny (Ms. Sunny Kirsten)
josh@v1.UUCP (Josh Knight) (03/10/85)
> I ask > because it occurs to me that frequencies such as "the radiation frequency > of neutral hydrogen atoms", while attractive as a physical constant, > seem to me to be as unlikely for use in everday communications by an > "extra-terrestrial" as they are here on earth. The Search for Extra-Terrestrial Intelligence (SETI) has received a great deal of attention from some very knowledgeable folks. A good compendium of this knowledge (I may be a bit out of touch) is NASA SP-419 "The Search for Extraterrestrial Intelligence" with a section on why one would look at the "water hole" (another popular place to look besides the neutral hydrogen frequency) by Bernard Oliver: "The Rationale of a Preferred Frequency Band: The Water Hole". The frontspiece says it is available from the Superintentdent of Documents, U.S> Government Printing Office, Washington, D.C. 20402, stock number 033-000-00696-0. Eugene Miya might be able to help more, the document was "prepared" at NASA Ames. There was also an earlier study of how to look for extra-terrestrial life: "Project Cyclops: A Design Study for Detecting Extraterrestrial Intelligent Life", also from NASA Ames, CR 114445. It claims to be available to the general public from Dr. John Billingham, NASA/Ames Research Center, Code LT, Moffett Field, California 94305, but that was 10-12 years ago now. The basic reason for looking at one small frequency range is that you need to know where to look. You have to look at lots of places in the sky and, if you are to be able to detect the signal, it needs to be a relatively narrow frequency band. Radio signals propagating through interstellar space propagate at a rate that depends on frequency so signals with a large frequency band "disperse". The amount of dispersion depends on the distance travelled, so that if you weren't using narrow band signals, you'd need to know the distance to the source as well as the direction. There is also "noise" (signals from sources besides extra-terrestrials) that needs to be avoided, and it turns out that you want to look in the range of 1-10 GHZ (the neutral hydrogen frequency is about 1.42 GHZ = 1,420 MHZ). The opinions expressed are my own, not those of my employer. Josh Knight, IBM T.J. Watson Research josh at YKTVMX on BITNET, josh.yktvmx.ibm on CSnet, ...!philabs!v1!josh
eugene@ames.UUCP (Eugene Miya) (03/14/85)
> > Astronomers are listening with radio telescopes for signs of > > extraterrestrial civilizations. > > So far we've heard nothing from another civilization. If there are > > other advanced lifeforms -- then perhaps we haven't tuned in at the > > right time on the right channel in the right direction in space -- > > yet. > Perhaps the more advanced civilizations use PSI (ESP) for > communication, rather than electromagnetic radiation. Why would they > use a frequency of Hydrogen when there's so much background noise in > the universe at those frequencies? Oh, I get it, they're probably > modulating the radiation from one of their stars? > -- > {ucbvax,decvax,ihnp4}!sun!sunny (Ms. Sunny Kirsten) this looks interesting. does psi/esp have some property which allows it to work beyond relativistic effects? :-) the quantity of time astronomers get to listen is painfully small. the dishes in use are partitioned just like telescopes between researchers. the bigger the dish, the greater demand [except for relatively fixed systems]. the problem is compounded because the same dishes are used to communications with deep space probes. the key is to use the existing time more efficiently to justify greater amounts of time. it is too bad more time cannot be alloted to this activity. --eugene miya NASA Ames Research Center {hplabs,ihnp4,dual,hao,vortex}!ames!aurora!eugene emiya@ames-vmsb.ARPA
rbg@cbosgd.UUCP (Richard Goldschmidt) (03/15/85)
> > I ask > > because it occurs to me that frequencies such as "the radiation frequency > > of neutral hydrogen atoms", while attractive as a physical constant, > > seem to me to be as unlikely for use in everday communications by an > > "extra-terrestrial" as they are here on earth. > For another source of info on interstellar communication see an article in Science 196: 616-621, May 6, 1977 "Searching for Extraterrestrial Civilizations," by Kuiper and Morris at JPL. It discusses some of the assumptions involved in devising a strategy. -- Rich Goldschmidt {ucbvax,ihnp4,decvax,allegra,ulysses} !cbosgd!rbg ARPA: cbosgd!rbg@ucbvax