I’ve been putting off looking into the SPOT Satellite Messenger, but I noticed this morning that the company is based in Milpitas, so it seems like a local connection obliges me to say something.

First, how it works: It tracks your location via GPS signals from GlobalStar satellites. It differs from GPS devices, though, because it has limited talk-back capability: you can send three kinds of messages: 911 for life-in-danger situations, “help” for when you need some kind of assistance but there’s no need to call in the cavalry, and “I’m OK” to check in with folks back home. The unit weighs about seven ounces, costs $150 plus $100 a year to subscribe to the online tracking service. Works in a lot of places with no cell phone coverage. A few choice links:

• Findmespot.com is the site for people who buy the gadget.
• GPS magazine has the most in-depth review I could find.
• Gear Junkie Stephen Regenold reviews it here.
• This thread at Backpacker.com has lots of real-world details about how it works.
• Doug Ritter of Equipped to Survive has many early details, but little actual real-world use.
• Backcountry skier Lou Dawson also has a preliminary review.
• This review mentions that it’s quite handy for aviators.
• Sierra Descents backcountry ski blog also reviews it, with nice caveats about its limitations and the ethical challenges it poses.

For an extra $50, you can sign up for a real-time tracking service that sends your location to the FindMe website and integrates it into a Google map. Cool, perhaps, but it sucks battery life bigtime, which is a major issue because the unit requires lithium batteries (alkalines will work, but they drain very quickly).

Many reviewers noted that the unit does a solid job of receiving GPS signals from satellites in varied terrain, including under forest canopy, but sending messages is another matter altogether — you need clear line of sight to the sky (a 30 degree arc, according to the folks at Backpacker magazine, which lavished Editor’s Choice status on it). Transmission is far more iffy in, say, canyons, ravines, or deep forest canopy — in other words, the places hikers most prefer to hike.

Bottom line: can it save your fanny if you’re in a tough scrape? My take: It depends. At the very least it can send rescuers to the last place where you’ve successfully sent an “I’m OK” message. That narrows a search considerably. If you’re out backpacking for a week, a simple “I’m OK” message can help the folks back home sleep at night.

I’m undecided but leaning toward getting one since I don’t own a cellphone — though the fact that I’ve hiked every weekend for the last four years without incident makes me wonder if I’d ever use it. This is a new product in a new market, and many more will arrive in the next couple years, doubtless with far more sexy features. Of course none of them will be any use to you if you slide down a canyon and break both legs next weekend.