To truly accept the idea of a personal locator beacon (PLB), you have to accept the idea that every spot on the Earth can now be seen by the network of satellites in orbit. There is no longer any place that is truly wild, unexplored, or free from the reach of technology, which flies in the face of the concept of adventure as self-reliance. But the upside is that when you find yourself staring down death somewhere in the back of beyond, a satellite beacon the size of a flashlight may well call in the cavalry.

These units, like ACR's MicroFix, are small (10 ounces), waterproof, and ideal for paddlers because they can easily be affixed to a PFD. PLBs send digital and analog signals to a multinational network of search-and-rescue satellites called COSPAS-SARSAT. Amazingly, they work. Paddler Robert Williams was wearing a PLB on his person when he capsized and lost his solo canoe on the Yukon River in 2004. The 62-year-old retired machinist from Sequim, Washington, activated his PLB and was rescued in four and a half hours.

Each PLB's digital signal includes a unique hexidecimal code, which corresponds to detailed registration information that you supply—everything from float plans and special health concerns to the phone numbers of loved ones. The satellites relay the signal to a local user terminal, which immediately passes the information on to the closest search-and-rescue authority. Usually—though there is no guarantee either implicit or implied—the rescuers arrive shortly thereafter.

“New technology has forever changed the wilderness equation,” Jacobsen says. “You used to be like a trapeze artist working without a net. You used to know you were on your own, alone. You had to rely on your self. Wilderness tripping will never be like that again.”

But beacons are nothing new. According to the National Oceanic and Atmospheric Administration (NOAA), the satellite system has assisted in the rescue of 22,412 people since 1982, when it was launched as a joint venture between the United States, Canada, France, and the Soviet Union. Those figures include rescues initiated by aircraft Emergency Locator Transmitters (ELTs) and marine Emergency Position Indicating Radio Beacons (EPIRBs), and, lately, PLBs. All three use the same technology and the same international rescue network, though PLBs are designed to be carried by a person rather than installed on a plane or ship. They have grown increasingly popular since 2003, when the FCC approved them for use in the continental United States. Signals from PLBs resulted in the rescue of 36 people in the United States in 2006, and 88 people in 2007. Satellite-based beacons, including PLBs, led to the rescue of 353 people in the United States last year, most of whom were rescued at sea.

The figures are increasing because these beacons are cheaper, more widely available, and more effective than ever before. While older, analog, beacons narrow the search area to about 500 square nautical miles—an area about three times the size of Chicago—the 406 MHz digital signal emitted by newer models carries registration information and usually can narrow the search area to less than three square miles. (The analog system will be phased out in February 2009.) Many PLBs also can send GPS coordinates to the satellite, narrowing the search radius to 100 meters.

So why would anyone choose not to use a PLB, especially on a remote expedition? For one, they are pricy—the ACR MicroFix retails for around $650. “That $600 is just not money well spent, as far as I'm concerned,” says Cliff Jacobson, a wilderness guide and veteran of canoe expeditions in the Canadian Arctic. “I'm not opposed to PLBs, but all they do is get you found. I would rather spend the money on a satellite phone and GPS so that I can talk to potential rescuers. And if you set that thing off accidentally, they are going to come and rescue your ass whether you want it or not.”

For one-off expeditions, it is often more cost-effective to rent a PLB from reputable dealers like A new option—though one that doesn't offer the complete global coverage of a PLB—is a device like the SPOT satellite messenger. The floating, waterproof unit, which works on the private Globalstar satellite network, retails for $150, with a $99 yearly cost for the satellite service, and another $50 per year for GPS enabling. The SPOT's GPS function even allows those at home to follow your progress on Google Maps, which is an enticing option in this blog-happy age. SPOT also offers the option to buy $100,000 worth of rescue insurance for $150. Since hitting the shelves in late November 2007, SPOT units have initiated four rescues.

No technology can change the fundamental truth of expedition paddling, however. “It's your responsibility to stay alive,” says ACR's marketing director Chris Wahler, who recommends including as much information as possible when you register your PLB, and keep that information up to date. And in the end, there's the question of whether you want someone to watch over you. “New technology has forever changed the wilderness equation,” Jacobsen says. “You used to be like a trapeze artist working without a net. You used to know you were on your own, alone. You had to rely on your self. Wilderness tripping will never be like that again.”