Here is an update which claims this storm could cause quite a bit more damage to satellites and the global positioning system than previously thought. Heads up on November 17th.

http://newscientist.com/ns/981003/nspace.html

-- Goldi (goldilucks@yahoo.com), October 14, 1998

Answers

I PREDICT that the Leonid shower, while causing a few problems, will not cause any major long term problems that can't be fixed or worked around. But I am writing this date down on my calendar as one to watch, as I have with all Y2k flashpoints. So far, all of my dates have come and gone and still no long term relationships! ;) (Just as well, I have a feeling that I won't like living with Y2k).

-- Kay P. (Y2Kay@usa.net), October 14, 1998.

They come and go every year, and we always take a little damage. If its worse this year then its worse. Its like a tornado, you just hope it doesn't hit dead on your house. But not to worry too much, even the worst meteor storm is unlikely to take out much of the satellite swarm around this planet - the leonid meteors are spaced out pretty far apart. Sure they look pretty when they burn up in the upper atmosphere, but you are seeing the ones that strike anywhere from right above you to thousands of miles away. Even several thousand meteors visible from your position amounts to only one or two per square mile - and a satellite is a mighty small thing compared to a square mile.

-- Paul Davis (davisp1953@yahoo.com), October 14, 1998.

I've heard that the Leonid shower will be at it's height next year. However, I know that NASA and the Fed Gov is taking this shower very, very seriously. NASA has already said that the shuttle mission which includes John Glenn WILL be postponed if the very narrow window for launch is missed because of cloud cover or bad weather. They don't want the shuttle up in mid November.

One thing to consider. The shower is historically stronger every 32 to 33 years. That would mean that the last time the shower was at this kind of strength was in 1965/1966. WE DIDN'T HAVE THE INTRICATE WEB OF SAT SYSTEMS WE HAVE TODAY.

Already, plans for avoiding the shower include turning away the Hubble Telescope and any sat that could be effected.

Don't discount the ability of this event to do damage. The damage this year may be minimal, because, there is always next year, just in time for that little roll over event thingy...

oh, and then there is the 23rd cycle of solar max... but that's a whole other story NASA and the Fed Gov is watching... can you say DEFCON? _______________________________________________________

-- Michael Taylor (mtdesign3@aol.com), October 14, 1998.

To show the relative importance of things: Jean is also real worried about this shower.

She's afraid it will be cloudy, the moon will be in the way, or there will be too many lights, and she won't get a chance to see it!

-- Robert A. Cook, P.E. (Kennesaw, GA) (cook.r@csaatl.com), October 14, 1998.

Robert, it is my understanding that in the US you will not be able to see the shower. It will occur during daylight hours. You could always take Jean to Japan. :-) How about that Jean?

-- Gayla Dunbar (privacy@please.com), October 14, 1998.

I'm hoping there will be some precusors and stragglers still present in the early morning and late evening the day before .

-- Robert A. Cook, P.E. (Kennesaw, GA) (cook.r@csaatl.com), October 14, 1998.

Paul,

The Leonid is different from other periodic showers:

As you can see from the fact that the earth will swing through its path in less than 1/2 evening (only the skies above the Far East (Japan, Korean, East Siberia, China will get hit), it is a very tight stream of debris.

The 33 year periodicity means it is also a closely packed stream (most particles are very close together along their orbit around the sun) so this is actually going to be more like an actual impact with a dust/gravel cloud than a "meteor shower" like the others we are used to.

I just hope "we" have looked at the cloud visually and found nothing bigger than gravel and small rocks.

But how would you check if this has been done? Comments anybody? Who do you contact? Officially or unofficially?

-- Robert A. Cook, P.E. (Kennesaw, GA) (cook.r@csaatl.com), October 14, 1998.

Here's some addditional information on the Leonids that I found yesterday: Understanding the Leonid Meteor Storms

-- Max Dixon (Ogden, Utah USA) (Max.Dixon@gte.net), October 15, 1998.

Robert you couldn't see anything with an optical telescope if you happened to look right at the densest part of the Leonid shower a few hours before we entered its orbit. By far the greatest part of the mass of the stream is fine dust. There are a few larger chunks, but very few. I don't know if anyone has tried radar mapping to determine the thicker parts of the swarm or not.

(BTW - there is a swarm of particles you can see with the naked eye if you are under a very dark sky and have very good eyes. There is a swarm that has settled in the L4 and L5 positions 60 degrees ahead and behind the moon, and when they are in the position of maximum illumination {when they are where the full moon would be if it was full} you actually can see a glow in that part of the sky!)

Meteor showers are actually particles left along the orbit of a comet along its lifetime. As the comet evaporated, the solid particles were left following the same orbit as the original comet. Over time gravitational pertubations and pressure from light and the solar wind will erase the shower by spreading it out till it is undetectable from the 'background count' of meteors at one every 10 minutes or so. When looking for meteors the only thing you have to remember is that meteors do not fall to earth - they are falling to the sun - the earth just gets in the way. So most of them will be seen when your part of the earth moves into the stream and the geometry is right so you have them coming down directly overhead - its hard to visualize but about 2:00 am is the best time. If you are lucky the earth will move into a fairly thick part of the stream about that time, and you get to see a lot of meteors.

As for satellites - there is not much worry about a com sat or such being hit by a large (.1 gram or so) meteorite. The thing to worry about is a number of hits by really tiny dust particles that abrade away critical surfaces. Turning the Hubble away from the shower to protect the mirror is a logical move. But I don't think it is very likely we will have a large fraction of the sat swarm go down.

-- Paul Davis (davisp1953@yahoo.com), October 16, 1998.

One cannot compare the Leonid meteor shower to the average meteor shower in it's ability to damage satellites. An average meteor shower is around 60 per minute. Leonids will check in around 10,000 per minute. As previously stated, we did not have the huge quantity of satellites in orbit the last time this density occurred. There are around 600 satellites at risk. Last go around there were less than 5. I would be taking precautions about having telecommunications and the GPS down for a period of time. It's anyone's guess as to how long. I haven't seen anyone stating that they have spare satellites sitting around waiting to be launched.

-- Goldi (goldilucks@yahoo.com), October 16, 1998.

The November issue of "Sky & Telescope" magazine contains a wealth of good information on the Leonid meteor shower. Whether the annual shower will become a full-fledged 'storm' seems to be open for debate. Even if there is a 'storm', we here in the US will probably not be able to view its 'peak' as eastern Asia will be in the best position. Some of the more notable quotes:

• ...David Meisel, executive director of the American Meteor Society: "Predictions of meteor storms are notoriously unreliable. No one realy knows how to do it properly."

• Any intense meteor storm will last no more than a few hours and perhaps less than one hour.

• Astronomers have long anticipated that 1998 and 1999 will offer the two best opportunities for a Leonid storm.

• Experts differ. Peter Jenniskens (NASA/Ames Research Center) has concluded that the Leonid peak will be attained on November 17, 1998 when "meteors may fall at the rate of 3 per second with occasional flares of up to 40 per second."

• Brian G. Marsden of the Minor Planet Center in Cambridge, Massachusetts, comments, "My own personal opinion is that we shall not see much in the way of a meteor storm in either 1998 or 1999" but he adds "it would be nice if I am wrong".

• And even if we experience significant Leonid activity in 1998 or 1999, Yeomans suspects that it will not achieve epic proportions. "In 1998-1999" he points out, "the earth will pass nearly three times as far from the comet's orbital path as it did in 1966 and more than 6 times farther than it did during the great storm of 1833."

• ...Yoemans gives 19:43 UT on November 17, 1998 and 01:48 UT on November 18, 1999 as the peaks.

• Thankfully, Leonid watchers face no hinderance from moonlight this year.

• The world's space agencies are nervously awaiting possible strikes to the more than 500 working satellites that orbit the Earth. Some satellites, including the Hubble Space Telescope, will be rotated to present their least vulnerable profiles to the potential sandblasting.

Except for this final quote, there was not much on the potential for satellite damage. They did say that even though the US will not be in position to see the 'peak' if a storm occurs, the shower itself should still be worth the effort for those people interested in watching such things. Arnie PS Any spelling mistakes in the quotes above were solely mine. Any factual errors are those of the authors.

-- Arnie Rimmer (arnie_rimmer@usa.net), October 18, 1998.

As a quick follow-up, the November issue of "Astronomy" magazine also covers the Leonids and this had an interesting side-bar entitled "Satellite Sandblasting". Some quotes:

• The problem is the speed of these particles, not their size. [...] typically smaller than the diameter of a human hair and no larger than a grain of sand but "the encounter velocity is enormous" [...] Leonid particles encounter spacecraft at about 71 kilometers per second (more than 155,000 miles per hour) [...] "The result is that even a grain of sand the size of the head of a pin has the same energy as a .22 caliber bullet."

• Though some satellites may be critically damaged by an impact with one of these speeding bullets, most will experience no more than a pitting of their optical surfaces and mirrors. During the short Leonid bombardment, it is estimated that satellites will experience 1 to 3 years of weathering that will degrade performance.

• The biggest threat comes from the formation of an electrically charged cloud called a plasma, or from free electrons on the spacecraft. At these velocities, the impact of the smallest particles can create a plasma. The sudden electrical pulse created by the impact can damage sensitive circuits and computers on the satellites in the same way a lightning strike can create a power surge that damages your home computer...

• Though most military satellites are combat ready - they are designed to withstand a nuclear assault - communications and weather satellites are another matter. Two of the precautions being taken to safegaurd these satellites include a powering down of sensitive equipment and repositioning.

• During the 1993-1994 Persids, the Hubble Space Telescope had its backside facing the radiant, while observations continued in the direction opposite the radiant.

• In 1993, the European Space Agency's Olympus telecommunications satellite was lost during the Perseid meteor shower.

• There is also anecdotal evidence that cosmonauts heard the sound of particles colliding with Mir during that same shower -- some of these impacts were said to have damaged the facility.

• In 1998, the Leonids have the potential to do even greater damage. This year's event will help scientists better prepare for the future.

Arnie

-- Arnie Rimmer (arnie_rimmer@usa.net), October 18, 1998.

Taking 5 meteors per second as the average, and assuming the shower lasts 5 hours we get 300 per minute, 18,000 per hour or 90,000 meteors total in excess of the normal background. The earth has a diameter of about 8000 miles, (atmosphere and all) so has a circular area to the storm of about (4000 *4000)*3.14 which gives about 5 million square miles as the size of the circular target we are shooting at. So a given square mile has a chance of 90000/5000000 or 0.018 of being hit by a visible meteor. Assuming that meteors too small to make a visible flash outnumber the visible ones by 100,000 to one says a square mile would expect to get hit about 1800 times. Most satellites are not all that big - about 6ft by 4ft is OK for an average - or 24 square feet. A square mile is 5280*5280 square feet or 27,900,000 sqft. So there are about 1,150,000 satellite sized squares in a square mile. That gives us a chance of about 640 to one of a satellite getting - odds go up for bigger satellites - down for smaller ones. So we might get one or two knocked out - or we might not get any knocked out.

Thats math looking at ya.

-- Paul Davis (davisp1953@yahoo.com), October 20, 1998.

One other point: since the advent of fiber-optical communications we are now a lot less dependant on satellites than a few years back, at least as far as communications is concerned.

Satellites are most important for broadcasting (TV, pagers) and of course for GPS. The latter is not critically dependant on any single satellite, though.

-- Nigel Arnot (nra@maxwell.ph.kcl.ac.uk), October 20, 1998.