The search has only just begun!

Space Probes - Space probes exploring the galaxy on behalf of other civilizations probably won't have to be within a stellar system to be able to detect whether or not they are inhabited by civilizations like ours  (i.e. advanced sensor technologies should permit them to operate at considerable distances, letting them examine multiple stars at a median distance between them and still be able to detect civilizations with technological and physical footprints, if, and that's a BIG IF,  they are like ours, i.e. light pollution, EM leakage, modification of planetary surfaces etc.) 

Space probes sent by E.T.'s or machine life may not be interested in communicating with us but might consider us a limiting factor in their exploration or exploitation of a stars/planetary system's or galactic regions resources.  One could surmise that it may be impossible for us to detect a probe that is just a little bit more advanced technologically than we are, so I think we might assume that the only probes we will find are those that are intended to be detected.

Berserkers - The idea of machine life or probes turning against their makers is an old science fiction genre, such as the Berserker series by Fred Saberhagen, HAL from Arthur C. Clarke's 2001, NOMAD [Star Trek TV show] and V'ger [Star Trek movie] and others) and are an interesting genre; is science fiction sometimes predictive of reality?  Our only hope can be that E.T. probes are from altruistic civilizations; the other options don't work out for us.

Un-Identfied Flying Objects (U.F.O.'s) 

In 2005 there was a television special presented on the Primetime program by ABC News that was watched by perhaps ~11.5 million people, (which the following link will tell you a little more about that show at http://abcnews.go.com/Technology/Primetime/story?id=468496 )

On that site they say that nearly 50% of people in the United States believe in UFO's.  On that show several prominent SETI scientists appeared such as Jill Tarter, Seth Shostak and Frank Drake and they gave brief comments regarding UFO's.  At the end of the program, Dr. Michio Kaku (co-positor of string theory) basically (IMO) presented a challenge to the scientific community to take more interest in the scientifically forbidden subject of U.F.O.'s . 

There are many respected scientists (and many who are now deceased) who lent philosophical weight to the possibility of ET spacecraft travelling about the universe.  I have written in the past about the apparent lack of interest in the subject by modern SETI research institutions (perhaps for fear of the giggle-factor and a nagging lack of physical evidence :^)  but I really think that we are beyond that now (the giggle-factor that is.)  It seems  thoroughly UN-scientific to keep rejecting the subject out-of-hand.  No doubt many SETI scientists have carefully considered the subject before coming to their conclusions, but to constantly exclude the possibility that there are probes on the argument that "it is extremely difficult to send spacecraft over such huge distances" is to me a monument to ignorance.  I laughed hysterically when they presented Stanton Friedman as a UFO promoter, and a few nights later I heard his (seemingly angry) rebuttal in which he called SETI a cult.  Others have said that SETI researchers are ignoring the subject so that they can continue to have a job (obviously nothing could be further from the truth!!) but I really think that perhaps a weakness of SETI is that there is no scientific-arm of investigation in this area (not following
up on hearsay that is, but actively looking for probes.)  I think that perhaps the scientific institutions conducting SETI and the scientific community in general should consider Dr. Michio Kaku's (seeming) challenge, and get over their UFO'bia.  It's doubtful that some (if not all) UFO's are E.T. sent spacecraft, but in my opinion it's un-scientific to not look for them considering the probability that they probably are as existent as the space probes we use.

SEARCHING FOR SPACEPROBES AND RELICS 

What do we mean by searching for probes? Consider for  example "Probing for ETI's Probes in the Solar System" by JPL engineer
Scot Stride at http://www.setileague.org/editor/stride2.htm

And also this interview with Scot Stride by Astrobiology Magazine

Can SETI Probe for Probes? Interview with Scot Stride

http://www.astrobio.net/news/article919.html

Which indicates that, amongst other things, the SETI Institute's Allen Telescope Array may be well-suited to this kind of search.

(That article also happens to make a reference to something I did awhile back called SATURN AND ITS MOONS AS A SETI CANDIDATE? at the following link

http://www.geocities.com/exosearch/iapetushypothesis.htm )

and then there is a search for relics.  Is there anybody looking at the data and light curves of asteroids or scanning the thousands of images streaming in from Cassini and Mars or pouring over the thousands of moon images (that are not available on the internet!) to look for ET relics?

Is anyone assigned to do research like the
following 1986 paper "On the detectability of antimatter propulsion spacecraft" by M. J. Harris?

http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1986Ap&SS.1...

Has anybody done magic SETI freq. searches on the moon?

Does the Moon's light spectra have any spikes in chemical or energy levels that seem extra-ordinary?  (Artificially added spectra changes from a distance or direct broadcast from the surface?)  Is anyone examining how to look for a radio-silent Voyager-like craft if it were passing through your system either radar, or some other type of active EM illumination like IR, U.V. X-rays etc.)

Is anyone looking for radio-live probes?

Is anyone doing a systematic analysis of the data from asteroid search programs for ETI probes via looking for peculiar light curves, trajectories or suddenly missing asteroids that might betray the presence of an ETI probe.  Is anyone examining data for asteroids that exibit peculiar, a-natural shapes?

Is anyone condering ways of capturing or looking for micro or
nanoprobes that might deployed on Earth?  (Anybody looked inside of an MRI scanner for stuck ETI probes lately? :-)

Have we pinged each planet with the Arecibo radar at the "magic" freqs. and see if there is a response from an automated ETI probe? (no)

Do any spectra of any terrestrial bodies indicate bizarre alloys in any particular crater? (relic impact puddles)

Jason H. 

CAN WE DETECT SPACE PROBES SENT BY OTHER CIVILIZATIONS?

SHOULDN'T E.T.'S USE SPACECRAFT FOR THE SAME PURPOSES THAT WE DO?  (EXPLORATION/RECONNAISANCE, SCIENCE AND COMMUNICATIONS)