By Dr. Philip Baczewski, Associate Director of Academic Computing

Welcome to the Inter(galactic)net

Wireless networking has become almost ubiquitous. Whether it is on campus or down at your neighborhood Starbucks, your laptop or PDA can be just a few clicks away from communication without the need for the tether of a network cable. As long as you are within 50 to 100 feet of a wireless base station, you'll be communicating with speed and ease.

Deep Space Network

But what do you do if your base station is 105 million miles away? NASA has had to solve that technology problem to communicate with its manned and unmanned spacecraft and in particular to control and communicate with the Mars Exploration Rovers, the first of which (Spirit) recently landed successfully on Mars. Supporting this communication effort on earth is NASA's Deep Space Network which consists of disk antennas in California, Spain, and Australia. These are each one third distance around the earth from each other consecutively and assure that at least one antenna will be pointing in the right direction to send or receive to and from a remote craft.

The Deep Space Network has been in operation for 40 years as of December 24,2003. The same antennas receiving the latest images from the surface of Mars also showed us men walking on the moon and a close-up view of the rings of Saturn. It is, in effect, one giant base station for communication with various craft in space.

On the other side of this connection is the Spirit rover which has three antennas and two ways of talking to its home base. It can send information directly to earth at a data rate of 11,000 bits per second or send information to one of the craft already orbiting Mars, such as the Mars Odyssey, at a rate of 128,000 bits per second. Information transmitted via the latter method can then be relayed from the orbiting craft to earth.

11,000 bits per second is about one thousand times slower than your average Starbucks session but it does still get the job done for NASA, especially to send brief commands to the remote rover or to receive status information from the rover in a compact format. Don't look for the Mars rover to be downloading the latest Star Wars trailer any time soon, however. 11,000 bps was barely fast enough to do e-mail on earth (at least 9600 bps modems were a huge jump up from 2400 bps).

128,000 bits per second is about twice the speed of a current-technology dial-up modem. About the same speed as dual=channel ISDN, such a network connection would give you reasonable Internet service on earth. At this speed the Spirit rover can send information at a much faster rate to one of the Mars orbiters and NASA anticipates that as much as half of the data sent back to earth from the Mars rovers will be transmitted via this relay method. There is even the possibility of testing a European orbiter as a possible relay point.

A Network of Satellites

One of the NASA Jet Propulsion Laboratory's (JPL) projects envisions an eventual network of satellites around Mars to support data transmission from robotic (or maybe human) explorers. This Mars Network would ring the planet with "Microsats" and be able to relay information from any point on the Martian globe. One can only imagine the cost of unlimited daytime minutes on that network.

A communications network with relay stations on other planets, near-earth planetary, orbit and perhaps on the earth's moon starts to sound like a fairly extensive network. While it may be a while before we can browse the Internet from our PDA on the moon, pushing the human communications infrastructure farther from our planet can only yield technology improvements here on earth. While the power and capability of our communications devices increases their size decreases, but the amount of data we are used to exchanging seems to continually grow.

All that on a cell phone?!

I can now read E-mail on my cell phone, but I won't expect to be watching downloaded movies via that wireless network any time soon. But advances in information management, compression, or transmission could greatly increase a cell phone's capability without requiring tremendous advances in hardware technology. In the mean time, I'll just have to be content to browse images from Mars on my PDA while sipping a nice hot cup of coffee.