Getting the intergalactic message across is easier said than done

Scientists recently decoded the first confirmed alien transmission from outer space. It said:

"Please send 5x10 (to the 50th power) atoms of hydrogen to each of the five star systems listed below. Then, add your system to the top of the list and delete the system at the bottom. Transmit copies of this message to 100 different solar systems. If you follow these instructions, you are guaranteed that within 0.25 degrees of a galactic rotation you will receive in return sufficient hydrogen stores to power your own civilization until the universe reaches inevitable maximum entropy. This really works!"

OK, it's only a joke, a cosmic/comic chain letter that's no more likely to happen than, well, promises of chain letters of the terrestrial type. But that's not to say there isn't an alien civilization somewhere in the far reaches of space with the ability -- and desire -- to communicate.

Why else do serious scientists at SETI -- the Search for Extraterrestrial Life -- scan the heavens for alien signals? Why did NASA stick iconic plaques on its first interstellar probes?

Just recently SETI astronomers recorded a mysterious radio wave signal for the third time. Most researchers now dismiss the signal, dubbed SHGb02 (plus) 14a, as an artifact of random chance, cosmic noise or maybe just a glitch in the technology.

"The news was incredibly overplayed. There are always these anomalies," says Woodruff Sullivan, an astrobiologist at the University of Washington.

In 1961, a small group of space scientists gathered at the National Radio Astronomy Observatory in Green Bank, W.Va., to consider the subject of intelligent extraterrestrial life.

Much of the meeting focused on astronomer Frank Drake's new mathematical formula for estimating the likely number of alien civilizations in the galaxy capable of engaging in interstellar communication.

The Drake Equation, as it has come to be known, didn't prove anything, of course. It was based on numerous variables, most of which we still don't have any good numbers for. But the equation and the Green Bank meeting got people thinking about the challenges of communicating with alien life.

A year later, Soviet scientists gave it a shot, sending a pair of radar signals to Venus in Morse code. The first message read "MIR," the Russian word for peace and world. The second signal said "Lenin" and "SSSR" (the Russian acronym for the Soviet Union).

Neither message got a response, which probably isn't surprising, given the fact that Venus' atmosphere consists primarily of carbon dioxide with clouds of sulfuric acid and a mean surface temperature of 867 degrees. Surely there are more hospitable places to live in the universe.

Ten years later, in 1972, NASA launched the Pioneer 10 planetary probe, followed a year later by its twin, Pioneer 11. Tacked to antenna support struts on both probes were license-plate-sized, gold-anodized aluminum plaques etched with information intended for any extraterrestrials who might retrieve them during or after their missions to study Jupiter, Saturn and the outer planets of the solar system.

"The plaques were a last-minute effort," said Seth Shostak, a SETI astronomer. "It was realized that Pioneer would be the first human-made hardware to leave the solar system and never come back, so people thought it would be a good idea to install a builder's plaque."

The late astronomer and author Carl Sagan and Drake were hastily commissioned to design the plaques, which were engraved at a local bowling shop. The final etched message included schematics of a hydrogen atom, a binary number code, the Earthly origin of the probe and line drawings of a nude man and woman -- both of whom looked like they might have come straight from a Southern California beach.

Both probes are now well out of the solar system. Pioneer 10 is 7.6 billion miles from Earth; Pioneer 11 is similarly distant. Neither has been heard from since April 2001, when astronomers picked up a feeble signal from Pioneer 10 that measured just one billionth of a trillionth of a watt.

The Pioneer probes, which Shostak describes as a kind of "demo," helped inspire the next effort at interstellar talk: the so-called Arecibo Message, transmitted Nov. 16, 1974, from the massive 1,000-foot-diameter radio telescope at Arecibo, Puerto Rico.

The Arecibo Message was an electromagnetic version of the Pioneer plaques. It consisted of 1,679 bits of binary data that roughly described, among other things: our numbering system, the atomic numbers of certain key elements, the chemical structure of DNA, the Earth's population at the time and our location in the solar system. The radio signal was directed toward the globular cluster M13 in the Hercules constellation 25,000 light-years away, which means a reply cannot be expected for at least another 49,970 years.

After Arecibo, scientists returned to the idea of physical messages, attaching 12-inch gold-plated copper phonograph disks to the probes Voyager 1 and 2, both launched in 1977 and both ultimately destined for interstellar space.

Voyagers' disks were more sophisticated than Pioneers' plaques. They contained sounds and images meant to depict Earth's diversity of life and culture. There were recordings of humpback whales, crashing surf, elephant trumpeting and rocket launches, plus music from Bach and Chuck Berry and spoken greetings in 55 languages, some long-dead.

Each record was encased in a protective aluminum jacket etched with iconic schematics akin to Pioneers' and packaged with a cartridge, needle and user instructions (written in symbolic language).

The latest effort to communicate with possible alien life has been the most modest.

In 1999, a Houston-based company now called Team Encounter transmitted radio signals toward several stars located 51 to 71 light-years away. Dubbed "Cosmic Call" and sent from the Evpatoriya radio telescope in Ukraine, the series of binary code signals resembled the Arecibo message, containing descriptions of Earthly life, the solar system and some mathematical relationships. Reportedly, three similar transmissions have been made since, all seemingly to no avail.

What means do you use to communicate: physical objects such as plaque-bearing probes or electromagnetic transmissions, such as light or radio?

Once that's decided, what about the language and content of an interstellar message? Will recipients understand it? Do aliens know Morse code?

The first question recently came up for debate again when Christopher Rose, a physicist at Rutgers University, and Gregory Wright, an electrical engineer with Antiope Associates, also in New Jersey, published a paper in the journal Nature arguing that transmitting electromagnetic signals into space as a way of saying, "Hey, we're here!" was a waste of money.

If humanity wants to correspond with the cosmos, Wright and Rose write, it should send bulk mail: Messages inscribed onto physical matter and then launched toward planets or other celestial bodies deemed most likely to harbor responsive life.

The primary benefit of sending "messages in bottles," Rose and Wright said, is cost-efficiency. A radio transmission is faster. It travels at the speed of light. But the transmission spreads and dissipates as it moves through space. By the time a signal from the Arecibo radio telescope reaches Saturn, it has dipped below detection level. And once it passes a target, it's gone for good.

Sending a signal farther, say 10,000 light-years, would take a million billion times more energy than launching a message-bearing probe.

Conversely, wrote the researchers, physical messages aboard the Pioneer and Voyager space probes remain intact no matter how far they've traveled from Earth. Their primary drawbacks are numbers, size and speed. The handful of probes bearing messages are all very, very small in a very, very large space. Moreover, they're all moving relatively slowly.

Even traveling thousands of miles per hour, none of the Pioneer or Voyager probes will reach an interesting target soon. Voyager 1, for example, won't enter another planetary system for another 40,000 years. Pioneer 10 is headed toward the red star Aldebaran, 68 light-years away. Zipping along at 28,000 mph, it will get there in 2 million years.

All potential communication with potential extraterrestrials starts with some basic assumptions.

Assumption No. 1: Any alien recipient is at least as intelligent and technologically advanced as humans.

"We assume they have access to a radio telescope because obviously they would need to be doing some kind of SETI-like research themselves to detect our signal," said Yvan Dutil, a Canadian physicist who, with colleague Stephane Dumas, has overseen the Cosmic Call efforts.

"That means they need to be able to do the math to design their own radio telescope and be familiar with basic material physics to build it. It means they also have some sort of social organization because something like SETI is not likely to be the work of a lone individual."

Shostak put it another way: "Getting a message to bacteria on Mars would be a tough assignment."

Assumption No. 2: Everybody's speaking the lingua franca. In Hollywood, aliens speak English. In reality, experts say, a universal language more likely will be mathematics and physics.

"It goes to the assumption that the laws of physics are the same everywhere," said Robert Park, a professor of physics at the University of Maryland. "If aliens can figure out the laws, they're going to have numbers."

Still, there's no diminishing the toughness of the task. After the Green Bank conference, Frank Drake sent a coded message to his fellow participants. It was a sort of intellectual exercise. The message consisted of 1,271 ones and zeros (or bits) and was based on the key that 1,271 is the product of two prime numbers, 31 and 41. Even though all the recipients were human, spoke the same language and were familiar with Drake's work, only one scientist successfully decoded the cryptogram.

Communicating with pictures isn't necessarily easier. For one thing, what if E.T. can't see? Then there's understanding what you're seeing. Parts of the Pioneer plaques appear pretty obvious: the line drawings of a man and woman or the sequence of planets in our solar system, for example. But within the entire illustration lies a lot more embedded information, much of it based on the wavelength of photons and the transition frequency of hydrogen atoms.

"I've shown the plaque to lots of people, including some really bright students," said Park. "They couldn't make heads or tails of it."

The bottom line may be one of intent. If the idea is merely to make our presence known in the universe, then transmitting a strong, unnatural signal -- a radio or light transmission, for example -- might be enough.

"I've always gone for the idea of a beacon," Sullivan said. "It would be simple, a sort of 'I am here!' message that might also include some basic information about where to look for a weaker signal containing more information. That's easier said than done, however."

"The final frontier."

Billions and billions of chances to find ET. Imagine Pioneer wandering into a space trade lane like a dingy lost in a giant ocean highway of tankers or ore carries. The dingy would probably cause major confusion for a moment before being creamed by a larger vehicle. Space being 3 dimensional means that finding that highway would be very hard.

Thanks for posting it - great article!!!

"to boldly go..."

I liked the "don't break this chain" bit, but got worried. Supposed we get a lot more illegal aliens? Has Congress made allowance for special work permits for the "Slags"? Will Ahhhnold grant Drivers' Licenses? Then there is the whole issue of welfare, taxes etc. I say leave them where they are.

Scotty, sand by to energize.....

As a technogeek, I enjoy discussions of technology and the frontiers we have yet to conquer. Given the size of the galaxy, SETI could invest the next million years or so trying to communicate with alien life. While I think it possible that there are other life forms in the galaxy, our efforts to contact them to date are somewhat laughable, at best.

We need a means of sending out a mass mailing that has the capability to deliver a message and receive a response within a generation in order for the communication to be meaningful. Currently, physicists are working on teleportation and have succeeded in teleporting an atom back in time by one second. Granted, that's a baby step, but the potential is that by the end of this century, if development continues and if raw power requirements do not emerge as a limiting factor, we could be able to teleport physical messages across the galaxy.

Short of that, we need the means of capturing some of those alien space ships that infrequently visit our planet and find out where they are from. Then we take them to McDonalds and introduce them to earth food. (Yes, that's a joke)

The long and short of it is this - Star Trek doesn't have to remain in the realm of science-fiction. Throughout history, science-fiction has consistently found a way to become science fact. Absent the ability to short-circuit the space-time continuum (not on the radar screen at present, to the best of my knowledge), our best hope of contacting other life forms may well rest with whatever advances we may make with teleportation.

There have been many "false hope" messages received in the past. Most of them originated from earth years ago, and having traveled in space until bouncing off a terrestrial body and returning back to earth.

This was once labeled "Pluto Bounce", but I am sure there is a more modern label attached to the phenomenon.

Moon Bounce, also known to Ham Radio operators as EME (Earth Moon Earth) is a form of communications used on VHF Frequencies and above. It relies on the minimal (some consider it to be zero) attenuation of radio signals traveling in free space. In earth speak, this means that a radio signal traveling up does not lose any power. When it is traveling from one point to another for terrestrial (earth) communications, a VHF (and higher) signal is limited by the curvature of the earth, and is considered a "line of sight" transmission - as a rule. Once it is directed up, it is theoretically unlimited in it's travel.

"Pluto Bounce" has allowed for the reception of Television and radio signals from stations that "went dark" (have been off the air) years ago. This proves the concept of the speed of light, and gives an indication of how far the signal traveled; once the original broadcast date can be confirmed.

I have made use of "Meteor Scatter" to make contacts with stations normally far beyond the range of VHF communications. This is a method of bouncing a signal; off the rock concentration during peak meteor showers at various times of the year.

There is certainly something else up there. The techniques of communications are expanding by leaps and bounds, and sooner or later someone is going to receive somethigng that wasn't originated on earth.

I hope we know what to do with it when it happens...

I like the idea of trying to talk to some other enties, but who says that they are not watching us. Our electromagnetic signals have been leaving our planet since the early 1900's. Some of those signals show us [on this planet] at our worst [WWI,WWII, Korea,Vietnam,ect...] [And our best rescue efforts, disaster relief ect...]
Maybe they [the ET's] are observing us from a distance [say the outer system limits] trying to figure out when and if it safe to contact us.

The alien from Predator is quite as likely as the one from ET to show up in response.

Perhaps. But a world of vicious Predator-like monsters would not develop advanced technology, or last long if it did. Our chances of contacting it are small. If we do contact another form of intelligent life, by the rules of probability, it will be a very stable and long-lived society that has solved the problems of war and strife.

Personally, I am coming to believe that they are not out there, or we would have found proof by now. We're it, guys, the pinnacle of creation.

-ccm

a radio signal traveling up does not lose any power.... Once it is directed up, it is theoretically unlimited in it's travel.

Yes and no. The net energy of the signal in free space, integrated over the entire wave front, is undimmed. But the photon flux at any given point on the wave front falls off in accord with the inverse-square law. That is why radio telescopes are so large. The measurable signal power at any given point falls off pretty rapidly with distance, all other factors (like antenna size) being equal.

-ccm

This idea of trying to signal our presence to the universe might possibly turn out to be a really bad one.

If there was ever any doubt about our existence to ET it was eliminated in August of 1945.

Moon Bounce, also known to Ham Radio operators as EME (Earth Moon Earth) is a form of communications used on VHF Frequencies and above.

I had a neighbor for about 10 years that was big into Ham Radio. His claim to fame was that he had talked to all 50 states using moon bounce and, according to him, he was one of the first 100 or so to do it. He messed up his eyes doing it because he used a yaggi antenna and aimed it visually. The back lobe of the signal created by the antenna fried his retinas.

I agree. God had to start somewhere. No matter what way you look at creation (Evolutionism or Creationism) the Universe has a finite begining. You have to start somewhere! We know there is life here. Until we find evidence of something or someone else out there, I will maintain that there isn't any.

The Universe is ours. Now all we have to do is go take it!

I'm not sure I agree completely with you.

It does indeed seem likely that any species which developed interstellar travel would have moved beyond intra-species warfare. Any species which did not get past this would probably exterminate themselves.

However, I can easily envision an advanced species, completely peaceful among themselves, which believed it to be their racial duty to dominate or exterminate all other forms of intelligent life.

After all, the Nazis were in many ways more technologically advanced than the Allies in WWII. Many of the most advanced contributors to the development of the atom bomb were refugees from the Nazis. A slightly less virulent form of racism would have allowed the Nazis to take advantage of their expertise and we would have been in serious trouble.

Interstellar Nazis on a mission to purify the universe from lower forms of life!

Sounds to me like a good reason to keep a low galactic profile.

""Pluto Bounce" has allowed for the reception of Television and radio signals from stations that "went dark" (have been off the air) years ago. This proves the concept of the speed of light, and gives an indication of how far the signal traveled; once the original broadcast date can be confirmed."

The "Pluto Bounce" would only let you see stations that went dark about "11 hours" ago, not years ago.

Pluto is only about 5.5 lighthours away, not multiple lightyears.

So I could watch last night's Leno if I forgot to record it.

Right up there with the "my cellphone fried my brain" stories.

Apples and oranges. You cell phone doesn't fry you brain or cause cancer because you body is comprised primarily of water and the RF energy won't penetrate your body such low power levels (.6 watts on a typical handheld cell phone) It's called skin effect. RF doesn't like to penetrate water unless it is highly concentrated and relatively high power, like in a microwave oven (800-1000 watts typically). Your eyeballs, and in particular your retinas, are easily damaged by RF, particularly concentrated, higher frequency RF. I've commissioned about 7,000 cellular telephone sites and about 1,500 terrestrial microwave sites in the past 16 years and I assure you I take great strides to protect myself from RF exposure, especially to the eyes, when I'm working with higher power, higher frequency stuff.

Good point. I just think it is ludicrous for us to assume that any other species we come in contact will inherently be wise and benevolent.

Just imagine another species making a similar assumption about us.

Big mistake.

Obviously, the ability to travel between the stars presupposes a high technological level.

But technology is morally neutral. And another species might have an utterly different definition of morality, one which could include a moral obligation to wipe us out.

"Right up there with the "my cellphone fried my brain" stories."

Wavelength plays in there. What is the wavelength of you cell phone in relationship to the average height of folks using them.

When someone is using a highly directional antenna, it highly directs the signal. Gain is also an important factor, and in UHF (and above frequencies) used for EME< it is easy to create an unbelievable amount of gain in a small package.

You will find that antenna gain is far more important than brute force power levels.

Terms such as ERP (Effective Radiated Power) indicate the actual output of a transmission system taken into account power fed to it, gain if antenna and loss of coaxial cable between transmitter.

IN the case of your cell phone, if you were using an older car phone, which you were able to hold next to your noggin'; you would get a maximum of 3 watts exposure - only if you were between cells and the control channel was telling your phone to transmit at maximum power.

If you are using a handportable (Handheld cellphone), the max it can squeak out is .6 watt. Both signals going out through an omnidirectional antenna that offers little (if any) gain. Most cell antennas are designed as "helical dummy loads" - geared more toward protecting the output stage of the phone from damage that providing gain.

To summarize, if someone is boresighting a target using a highly directional antenna that is actively emitting a signal. there is a very good chance for retinal damage. I

However, if someone is holding a cell phone that is transmitting a maximum of .6 watt through a lossy antenna system that is designed to be more of an idiot proof appendage than one offering even unity gain, it is unlikely that any brain heating; much less the famed 41.11 Celsius will ever occur.

"Yes and no. The net energy of the signal in free space, integrated over the entire wave front, is undimmed. But the photon flux at any given point on the wave front falls off in accord with the inverse-square law. That is why radio telescopes are so large. The measurable signal power at any given point falls off pretty rapidly with distance, all other factors (like antenna size) being equal."

All absolutely true. That is what I used the term theoretically. However, I should have been more consistent throughout.

I have worked through satellites in High earth Orbit distance with less than 25 watts output.

All satellites must be self sustaining, generating their own power. For this reason, their actual output power is very small.

Handheld dualband rigs using a handheld cross polarized antenna have been used to make LEO (low earth orbiter) contacts (Approx 400 miles) with less than 1 watt.

I have made contacts to/through MIR, STS Shuttle SAREX equipped missions and ISS using 50 watts or less an antenna with no gain at all

That kind of distance using relatively low power demonstrates very minimal real-world attenuation; which is the point that I was trying to make.

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