By Gerry Blackwell

January 15, 2004

NASA is testing Tropos Wi-Fi mesh network gear for possible use on future missions to the red planet.

It’s a great story and a defining public relations opportunity for Wi-Fi infrastructure vendor Tropos Networks.

NASA, the National Aeronautics and Space Agency, chose Tropos’s Wi-Fi cell technology to test this year at its annual space simulation exercises in the Arizona desert near Flagstaff. Even better, NASA liked what it saw.

Don’t expect to see Wi-Fi blasting off anytime soon, though. The space agency moves at something less than the speed of light on decisions about which technologies to use on missions.

Each year NASA takes a suite of innovative communications technologies to a site near a meteor crater that closely resembles landscapes astronauts might encounter on Mars or the moon.

This year it was testing the possibility that it could use low-cost Wi-Fi equipment — specifically Tropos’s semi-proprietary mesh network technology — to deploy mobile hotzones during planetary exploration, possibly on future Mars missions.

“They’re looking to see what they can do using commercial off-the-shelf technology with small modifications as a way of really trying to keep costs down,” explains Tropos vice president of marketing Bert Williams.

In one scenario, astronauts would communicate during walks on the surface using Wi-Fi-enabled portable computers sewn into their space suits. In another, crew would deploy swarms of Wi-Fi-enabled robot vehicles to explore for water or perform other scientific experiments.

NASA is looking at the idea of using mobile Wi-Fi infrastructure mounted on vehicles so that it could be redeployed on an almost daily basis to “light up” different areas for high-speed wireless connectivity in support of scientific explorations.

Why would astronauts need broadband wireless communications when walking on the surface of Mars? It comes down to economics, explains Marc Seibert, a senior research engineer at NASA’s Glenn Research Center in Cleveland.

Donning a space suit and going outside on Mars is a very expensive proposition. NASA needs to make the most of every “suit run.”

The wireless technology would allow them to transmit data back to earth in real time. Scientists could see what the astronauts were seeing and see the results of experiments right away — and possibly redirect them to a different area, or have them do other tests or measurements that would yield important results.

The fear is that if astronauts simply follow a script written by the scientists — as they have done sometimes in the past — something really vital might be missed until after it’s too late to go back and confirm it.

“We might find out when they get home from Mars, for example, that at one point they were 30 meters from water,” Seibert says. Water is NASA’s Holy Grail, which could indicate the possibility of life in space.

The agency was duly impressed with the Tropos technology, which is designed for use in outdoor networks covering large areas of a city — or planet. The company’s main customers today are police and fire departments looking for city-wide high-speed network access.

“The Tropos hardware has two things going for it that others we tested do not,” says Seibert. “First, the transmit power is ten times higher than most other access points, a full watt. The other aspect we liked is the built-in proprietary mesh routing.”

Unlike some mesh networks, Tropos creates the mesh infrastructure using only access points (APs), not client devices. When installed, Tropos access points self-configure and automatically route traffic through the mesh to create optimum connections between distant nodes. They can also self-heal around local network outages.

Any Wi-Fi client device will work in a Tropos network, but only Tropos access points can be nodes in the mesh.

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NASA’s Arizona trial systems featured two- and three-node Tropos networks. Three access points turned out to be enough to cover an amazing two square miles.

Williams hastens to point out, however, that in a more conventional urban environment — with obstructions largely absent in the desert (or on Mars) — it takes nine to 16 Tropos access points per square mile, or one every third or quarter of a mile, to get seamless coverage.

NASA and Tropos used IPerf network performance monitoring tools to test communications between a server at a simulated base camp and a mobile test computer. IPerf provides what Tropos calls a “goodput” measurement — the effective data throughput between two nodes.

The results were impressive. NASA engineers measured a reliable 1 Mbps at a range of 1.3 miles using a laptop with no external antenna inside a moving vehicle. A 1-Mbps link as measured by IPerf, is probably 20 to 25 percent faster than a link measured at 1 Mbps by conventional tests, Williams says.

The mere fact that NASA chose to investigate Tropos is a feather in the company’s cap. That the agency was impressed enough with the technology to be willing to talk about it is even better. The NASA testing sends a message Tropos is very anxious to get out there.

“We want people to start to think of Wi-Fi outside the hotspot,” says Williams. “Most people think of it as an indoor technology for the home or office or the coffee shop. What we’re all about is getting it out of the coffee shop and out of doors. And this illustrates in dramatic fashion that Wi-Fi can be used to build infrastructure for very large coverage areas.”

The NASA testimonial will be grist for the Tropos PR mill for months to come — and justifiably so — but all may not be exactly as at first appears.

For starters, Tropos was not NASA’s first exposure to Wi-Fi. It has tested equipment from about 30 vendors to date — though this was the first time Wi-Fi mesh or cell technology was added to the mix in a test, Siebert says.

The agency is also a long way from making a decision even about the viability of Wi-Fi in space. Despite similarities in terrain between the Arizona site and Mars, there are no guarantees the test results could be duplicated on the red planet.

One possibility is that dust in the Martian atmosphere would absorb so much RF energy that network range would be reduced to the point that the technology was useless — not just the Tropos technology, but Wi-Fi in general.

NASA Glenn and the University of New Mexico have just completed the first year of a three-year study that will use computer modeling to try and simulate the behavior of RF systems on Mars.

NASA rates any new technology on a mission-readiness scale. “The readiness scale is one to ten,” Seibert explains. “This technology is around two to three right now, although that’s somewhat subjective at this point. If it ever got to seven or eight, Mission Control might start looking at it seriously.”

Even if it does get to that point, Tropos has no lock on the NASA account. The agency expects to test other mesh products as they become available, Siebert says.

Tropos has until recently been virtually alone in offering Wi-Fi mesh products that create a mesh using infrastructure equipment. Others are now emerging.

Reston VA start-up BelAir Networks recently announced mesh products that it claims are “the first complete cellular LAN solution.” Firetide, another start-up, has new router products “for quickly, easily and affordably deploying large Wireless Instant Networks.”

Nortel Networks has announced plans to test “new public wireless LAN (local area network) architecture” with British Telecom and the Massachusetts Institute of Technology.

Tropos is well aware the competition might be intense. It also knows the sales cycle with this customer could be very long indeed. After all, nobody really knows if or when the agency will be able to fly a mission to Mars. Even the declarations of President Bush have said it will take several years.