Tsunami Warning From Space?

Peter bayley writes "Tell me I'm crazy or tell me someone has already done it — but wouldn't a satellite equipped with a laser be a great way to warn people of tsunamis? I was pondering how to warn people in remote coastal areas once evidence of a seismic incident has been received by the monitoring stations that have now been set up following the large Boxing Day tsunami. The idea is to illuminate the areas that are likely to be at risk with a bright (but not dangerous) light. People would be told to head to higher ground if such a light appears in the sky. Put the satellite in a geosynchronous orbit. Make it tunable so that different colors can convey different meanings. You would be able to warn anyone, anywhere they can see the sky. The laser could be directed to illuminate only those areas at risk, skipping unnecessary areas to save power. Power could be varied so that it is visible day and night and through cloud (raise the power where the satellite detects cloud cover). I emailed some people at NOAA about it but they said it would stand on too many toes by circumventing local emergency service organizations in the various countries. I replied that countries could easily opt out, in which case the laser would be turned off for those countries — but received no further reply. Anyway, I thought the massed minds of Slashdot would relish the chance to demolish my idea."

Comments

Cheaper solution

[mhajicek]

Wouldn't it be cheaper to hand out emergency radios that wait in a low power standby mode until a certain signal is received?

Re:Cheaper solution

[the_womble]

Living in one of the countries affected by the Boxing Day Asian Tsunnami, the problem was not lack of a way to reach people, but the lack of a mechanism to pass the message along. IN particular the people who had the warning, said they did not know how to contact the governments of some countries (which shows a worrying lack of resourcefulness, but that is another subject).

As you say, mobile phone penetration is easily high enough to work, but you will need to guard against hoax calls. A designated number of warnings would have to be well publicised.

Radio will work, but you hardly need to distribute them specially: just ask all radio and TV broadcasters to broadcast an emergency message. It may not work that well late in the night. For times like that vehicles with big speakers on them driving through towns with loud warnings should work well.

The laser idea is stupid: there are all kinds of lights in the sky to confuse people: I remember a huge number of people seeing "UFOs" in London in 1990 or 91 because someone said there was one on a popular radio station, so people started looking up and seeing all kinds of things they normally never noticed.

Terrible idea, of course, which is why we don't

[Anonymous Coward]

No, because the amount of energy, in the form of light, would be immense. You're talking at least 10 watts per square meter, much more during the daytime. Tsunamis can affect hundreds of miles of coastline.

By my impromptu math, you'd need at least a gigawatt of power to light up that kind of area. So a medium-size nuclear reactor in the sky.

How about, instead, we just use these devices that transmit sound and vision via lower-frequency light, aka radio and television? Cheap transistor radios are much, MUCH cheaper than launching a reactor into the sky.

So... it's a super hi-tech siren?

[chefmayhem]

They used to use warning sirens for that sort of thing. Far more low tech, but quite cheap, and a single siren can be heard for quite a distance. Just put them near the shore. Now, it's not nearly as cool as the satellite, but it would work if people are indoors and not looking out the window.

easier way to get the power

[r00t]

Look, we just need a bright flash of light. It doesn't have to be a laser.

Put up a large number of satellites, much like GPS or Iridium. Each one holds a 30 megaton nuke. When an area is affected by a tsunami, we set off all the nukes that would be visible above the horizon.

Tsunamis are rare enough that we can normally launch a replacement system fast enough, assuming we don't put spares in different orbits. Have replacements ready to launch.

Re:easier way to get the power

[Alsee]

Dear Iran,
This is a test of the Emergency Tsunami Warning System. Had this been an actual emergency these EMP pulses would have been followed by a tsunami. This concludes this test of the Emergency Tsunami Warning System.

-

And how about daytime?

[A nonymous Coward]

How you gonna get enough power to make daytime *brighter*?

Was the idea to cook people and see who notices?

How about bad stormy weather which the (visible light) laser can't penetrate?

You going to have geostationary satellites so far away as to multiply the power required and the tremendous power losses?

Or were you going to have low level satellites, and need thousands to make sure every inch of ground was within a few seconds of any satellite coming into position?

How about topography blocking line of sight?

There are so many FAILs all over this idea.

It's a comic book idea, should never have gotten past the hangover stage.

Re:Opt out?

[tibit]

I guess there's some misconception about what such a "light" would look like.

Everyone seems to react like this was going to be a streetlight type of a thing. You'd need a rather big nuclear powerplant to get that sort of power density on the ground. Assume we want 1W/m^2 on the ground, and a "square" area 5,000km on the side. That's 2.5E10 m^2, so you'd 25GW of optical power output for your illumination. How anyone sees that much power being generated in orbit using current technology -- I don't know. Even getting a 1MW generator in the orbit would be a big feat. You can't exactly put a chiller tower up there. Dissipating all the waste heat would be a huge fucking problem, no kidding.

For what's achievable with current technology, we're talking about a faint star that say can be red, green or blue. So beam forming to a point where "a country could opt-in" etc. is a fantasy at this point. How hard is it *not* to look up?