Frequently Asked Questions
How do you put a message on a laser?
A laser can be encoded with a message much the same way radio waves are encoded with messages. In fact radio waves and light are both different forms of electromagnetic energy. The easiest way to understand how the encoding works is to think of a flashlight that you can turn on or off to send a message. People have sent messages using flashing lights for many years, using "On-Off" patterns. Another example is the telegraph that was used to send messages using Morse Code.
As things progressed, engineers developed more ways to encode a signal, methods known as modulation. In every case there is a primary signal, or the "carrier," and something in the carrier signal is changed. The changes are what carry the information. Ordinary radio uses Amplitude Modulation and Frequency Modulation, or AM and FM. Amplitude modulation changes the amplitude or the strength of the signal. Frequency modulation changes the frequency of the signal.
Technology has continued to advance and today there are numerous modulation schemes. Fiber optic cables use advanced modulation techniques that use a beam of light, much like a laser, encoded with signals.
For sending signals into space we use a technique known as Pulse Width Modulation, or PWM. The laser beam is converted into a series of high-speed pulses, and the pulses have varying duration, or widths, according to the message signal. The changes in the pulse widths carry the information.
Why do you use lasers instead of radio waves?
Firstly, lasers don't spread out and weaken as quickly as radio waves do. While radio waves tend to spread out, lasers can remain in a directed beam for a long time. This property is known as "collimation." So that means you can direct them and all of the energy. Therefore the encoded message will be concentrated in that single direction. Secondly, they have pure frequency properties and are very controllable. Lasers use light frequencies, much higher than radio frequencies, so they can send information much more efficiently - the same reason fiber optics are superior when it comes to sending information.
How do you launch the message?
First we calculate the position of the destination. The destination coordinates are given in space coordinates of Ascension and Declination (space coordinates are explained in more detail in About Space). We convert the space coordinates to determine exactly where to point the laser. We confirm we have clear air with no cloud cover and good transmission properties. Then we confirm the position coordinates and destination in space using a Schmidt-Cassegrain telescope. Next we confirm that no aircraft are overhead. We also confirm that there are no satellite passes that would obstruct the signal. Finally we beam the laser with the encoded message. The transmission is at a low rate to ensure the best signal integrity over long distances.
How long will it take for the laser message to get there?
Even at the speed of light, which is the absolute fastest thing in the universe, it takes a long time. The number of light-years is also the number of years the light will be traveling. Our universe is that big, mindbogglingly large. That is also why it's cool to send a message using light. Light can reach out much farther and much faster than any spaceship will ever be able to do. Ever. So while you will never be able to don a space suit and travel at the speed of light, you can still send your thoughts (a piece of your mind, as it were) on an interstellar journey - a journey that will outlast our time here on Earth.
What if an alien gets my message?
Here on Earth there are people who "listen" for alien messages using sensitive equipment pointed at the sky. The organization that searches for extraterrestrial intelligence is known as SETI.
If, by chance, there is some form of alien life, there would still be a very very very small chance of any signal being detected. In fact, for any given planet, there would have to be very special and rare conditions for that to even be in the realm of the possible. The following conditions are also necessary:
A laser can be encoded with a message much the same way radio waves are encoded with messages. In fact radio waves and light are both different forms of electromagnetic energy. The easiest way to understand how the encoding works is to think of a flashlight that you can turn on or off to send a message. People have sent messages using flashing lights for many years, using "On-Off" patterns. Another example is the telegraph that was used to send messages using Morse Code.
As things progressed, engineers developed more ways to encode a signal, methods known as modulation. In every case there is a primary signal, or the "carrier," and something in the carrier signal is changed. The changes are what carry the information. Ordinary radio uses Amplitude Modulation and Frequency Modulation, or AM and FM. Amplitude modulation changes the amplitude or the strength of the signal. Frequency modulation changes the frequency of the signal.
Technology has continued to advance and today there are numerous modulation schemes. Fiber optic cables use advanced modulation techniques that use a beam of light, much like a laser, encoded with signals.
For sending signals into space we use a technique known as Pulse Width Modulation, or PWM. The laser beam is converted into a series of high-speed pulses, and the pulses have varying duration, or widths, according to the message signal. The changes in the pulse widths carry the information.
Why do you use lasers instead of radio waves?
Firstly, lasers don't spread out and weaken as quickly as radio waves do. While radio waves tend to spread out, lasers can remain in a directed beam for a long time. This property is known as "collimation." So that means you can direct them and all of the energy. Therefore the encoded message will be concentrated in that single direction. Secondly, they have pure frequency properties and are very controllable. Lasers use light frequencies, much higher than radio frequencies, so they can send information much more efficiently - the same reason fiber optics are superior when it comes to sending information.
How do you launch the message?
First we calculate the position of the destination. The destination coordinates are given in space coordinates of Ascension and Declination (space coordinates are explained in more detail in About Space). We convert the space coordinates to determine exactly where to point the laser. We confirm we have clear air with no cloud cover and good transmission properties. Then we confirm the position coordinates and destination in space using a Schmidt-Cassegrain telescope. Next we confirm that no aircraft are overhead. We also confirm that there are no satellite passes that would obstruct the signal. Finally we beam the laser with the encoded message. The transmission is at a low rate to ensure the best signal integrity over long distances.
How long will it take for the laser message to get there?
Even at the speed of light, which is the absolute fastest thing in the universe, it takes a long time. The number of light-years is also the number of years the light will be traveling. Our universe is that big, mindbogglingly large. That is also why it's cool to send a message using light. Light can reach out much farther and much faster than any spaceship will ever be able to do. Ever. So while you will never be able to don a space suit and travel at the speed of light, you can still send your thoughts (a piece of your mind, as it were) on an interstellar journey - a journey that will outlast our time here on Earth.
What if an alien gets my message?
Here on Earth there are people who "listen" for alien messages using sensitive equipment pointed at the sky. The organization that searches for extraterrestrial intelligence is known as SETI.
If, by chance, there is some form of alien life, there would still be a very very very small chance of any signal being detected. In fact, for any given planet, there would have to be very special and rare conditions for that to even be in the realm of the possible. The following conditions are also necessary:
- Have an atmosphere that allows light to pass; many planets are always cloudy.
- Have reached the right stage without destroying itself or being destroyed by natural disasters.
- Have the technology to detect ultra weak signals.
- Be interested in detecting life that is alien to their own world.
- Be expecting something from Earth and be listening at just the right time with sensitive equipment.
- Be able to decode the Earthly signal
