A THE TORONTO STAR Sunday, May 19, 2002 n SCIENCE If only ... · ed target with a coded radio...
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Product:STAR Date:05-19-2002Desk: NEW-0016-CMYK/18-05-02/20:06:18 n SCIENCE BY IAN STEER SPECIAL TO THE STAR W HEN A BOMB dropped by a U.S. Air Force F-16 blasted Alpha Company, 3rd Battalion, Princess Patricia’s Canadian Light Infantry in Afghanistan a month ago, killing four men and wounding eight, some sci- entists and many World War II veter- ans and buffs wondered why there was no IFF. IFF stands for Identify Friend or Foe, an electronic device invented by British boffins more than 60 years ago to prevent just such accidents happening. The first IFF units were developed in conjunction with the first radar units, says Richard Rohmer, former RCAF fighter pilot, retired major- general and a best-selling author. “Without those radars,” says Rohmer, “the war might well have been lost because RAF Spitfires and Hurricanes would not have been able to intercept the oncoming hordes of Ju-88s and Me-109s. What IFF did was allow allied pilots, coming back from raids over France, to let those same radars know our aircraft were friendlies, thanks to a little black box.” The principle behind the first IFF device — and all IFF units since — was simple. It challenge d the intend- ed target with a coded radio signal. If the target had the required IFF re- ceiver/transmitter and decoder/en- coder, it “authenticated” the target by returning the correctly coded IFF re- ply. Targets that didn’t so respond were presumed hostile. “IFF systems cannot do more than sort out the friendlies, ” Rohmer says. So none can tell (independently) actual foes from merely unknown and possibly innocent targets, includ- ing allied friendly forces without the right IFF or even one’s own forces with malfunction- ing IFF. The newest IFF systems use radars or lasers, as well as radios. There are different IFF sys- tems for the air force, army, navy and marines and, of course, different systems for differ- ent countries. Few of the dozens of systems now in use are directly compatible. Getting dif- ferent allied forces — as in NATO, the Persian Gulf War and Kosovo — with different systems to work to- gether and yet avoid such friendly fire incidents is a serious, ongoing challenge. Even the U.S. Army’s own troops do not generally — and until recently, did not at all — have any way to sig- nal an errant air force or navy aircraft (the ones with the bombs) that they are friendly. What our troops need, then, is a ground-portable version of the IFF system used by bombers. Within days of the accident, Ste- phen Trimble of Aviation Week & Space Technology magazine report- ed on the U.S. Army’s newest, ground-based IFF unit. The first most Canadians heard of the new system, known as the Enhanced Position Lo- cation and Reporting System (EPLRS, pronounced ee-plars), was an April 23 report by The Star’s Jo- seph Hall. “If it works as advertised, you’d think EPLRS is something you’d want to include in your minimum kit list,” says Jason Frye, a former para- trooper who served with the PPCLI and is now a Metro Toronto police of- ficer. “One per platoon would be a necessity if you’re in a battlefield.” EPLRS is more than an IFF system. Made by Raytheon Systems, it is a UHF radio a mere 25 centimetres wide, 35 cm long and 13 cm high. It’s highly portable, weighing only 12 ki- lograms, batteries included. The units fit in tanks and trucks and can be carried by paratroopers. Being UHF radios, EPLRS units can, through a central control known as a master station, exchange IFF handshakes with aircraft like the F-16. Airborne IFF signals are UHF, too. A secondary benefit of transmit- ting at such high frequencies is their use for sending high rates of data, like the position and location of friendly troops and units, reporting in a second-by-second system even in the midst of battle. EPLRS grew out of the PLRS, the Position Location Reporting System, still used by the U.S. Marine Corps. First tested in the late 1970s, the Ma- rines had about 2,000 PLRS radios and 35 of the required master sta- tions by the late 1980s. Work began on the U.S. Army’s new, enhanced PLRS in the early 1990s. Using VHSIC (Very High Speed Integrated Circuits), similar to those found in today’s computers and COTS (Commercial Off-The- Shelf ) technologies, they tripled per- formance for half the cost. With just one of these portable ra- dios and a master station at their base camp in Kandahar, a company of 12 troops (like Alpha Company) could travel up to 10 kilometres from base camp (about the distance they were) and have their location known at all times and protected from acci- dental attack. What’s amazing is that a full divi- sion of 10,000 to 20,000 troops, de- ployed with up to 1,500 radios avail- able per master station, can cover up to 150,000 square kilometres, an area one-quarter the size of Afghanistan. Networked together, the radios not only protect, they also form a wire- less WAN (Wide Area Network), through which the newest versions communicate at speeds fast enough to allow video conferencing and “live eye” aerial views through unmanned aerial reconnaissance vehicles of “enemies behind the hill.” By 2000, the U.S. Army had at least 2,000 of these radios. Another 3,000 are either delivered or on order and over the next few l years, total sales for all services and allies is expected to reach 30,000. Thanks to Jane’s In- formation Group, perhaps the pub- lic’s best source of military informa- tion, we also know at least some EPLRS units, and/or their PLRS pre- decessors ( just as capable IFF-wise) were deployed to the Persian Gulf War, Bosnia and elsewhere. It is hard to believe such systems are not now serving U.S. forces in Afghanistan. As retired Maj.-Gen. Lewis Mac- Kenzie, who commanded U.N. forces in Bosnia and once commanded the PPCLI, says: “If members of the American brigade (part of the U.S. 101st Airborne Division) our Canadi- an troops are attached to have access to this equipment, then certainly the equipment should have been provid- ed to our troops as well.” EPLRS radios are not currently in service and have not been ordered for Canada’s defence forces, con- firmed Lt.-Cmdr. Phil Anido, spokes- person for acquisitions at National Defence headquarters in Ottawa. Why? “Partly because of money.” According to Jane’s, 6,000 such ra- dios could earn Raytheon $450 mil- lion. So they could cost something like $75,000 each. That doesn’t in- clude service and spare parts, or the optional PC Ruggedized Laptop, probably around $75,000 itself. For a laptop? Yes, because “ruggedized” is military-speak for “bulletproof” and inside is a National Security Agency micro-miniature supercomputer, ca- pable of scrambling and unscram- bling coded communications that are otherwise unbreakable, including IFF. With no plan to outfit Canada’s forces, other more immediate op- tions might be to buy or borrow a few new EPLRS radios from the U.S. Ar- my or buy some used PLRS radios from the Marines. “The solution could be as simple as merely attaching a couple of guys from U.S forces with these radios to serve with our Canadian troops,” MacKenzie says. Asked about EPLRS in the House of Commons, Defence Minister Art Eggleton replied: “It’s not being used in this particular operation yet.” Ian Steer is a Toronto freelancer. If only they’d had an IFF PHOTO COURTESY OF RAYTHEON SYSTEMS LAVISH LAPTOP: A U.S. soldier demonstrates the EPLRS radio identification device and the “ruggedized” laptop, compatible with IFF systems. Below, a laptop screen displays friendly troops (blue Xs) and possible foes (red triangles). Modern version of a World War II device could probably have prevented ‘friendly fire’ tragedy in Afghanistan ‘If it works as advertised, you’d think EPLRS is something you’d want to include in your minimum kit list.’ wJASON FRYE, former paratrooper One of the most intriguing puzzles that the unravelled human genome might solve is the difference be- tween us and chimps. If you look at the genetics of both, there is a scant 1.5 per cent difference. But surely, for all the humanness of chimps, the gulf between the two species should be much, much wider than that. What gives? First things first. Measuring per- centages of genetic difference be- tween species is misleading. If the chimp comparison startles you, how about the fact that the ordinary mouse shares about 95 per cent of its genes with us? Pick a mammal — any mammal — and it will share all kinds of genes and groups of genes with us, most of them concerned with the basic housekeeping of a mammalian body. Add to that the fact that genes don’t correlate one-to-one with anat- omy. Dozens of genes are employed simply to maintain the ability of our blood to clot when we’re cut and we share those genes — or ones very much like them — with tigers, whales and anteaters. On the other hand, a single gene can regulate the activity of several others. And alter- ing a gene like that can change the shape and size of an animal. So matching genes between animals is a misleading exercise to begin with. Even so, the 1.5 per cent differ- ence between chimps and humans is still puzzling and important, wheth- er you want to emphasize our differ- ences or reaffirm our similarities. Two recent studies have addressed this subject and they show just how far away we are from understanding what’s going on. The first was a study published a few weeks ago that took a first stab at identifying differences in gene ac- tivity between the two species. Us- ing tissue samples from humans and chimps that had died of natural causes, the researchers found that the genes from both were equally ac- tive in the blood and liver but the hu- man genes were much more active in the samples of brain tissue. It wasn’t a case of gene difference but gene productivity. So these differ- ences, which might be crucial to the species disparity, wouldn’t even count as part of the 1.5 per cent difference. There were two interesting side- lights to this research. One, that two mouse species as genetically distant from each other as we are from chimps showed no such brain differ- ences. That just reaffirms that some- thing happened in our brains over the last few million years that sets us apart from the chimps. The second point is that these are all averages; surprisingly, the gene activity in one of the human samples was actually within the chimp range. A second chimp/human study was just released by neuroscientist Dean Falk of Florida State University. In something of a technological tour de force, she overlaid 3-D brain images of chimps and humans to get an idea where the significant differences were. It was tricky work because Falk and her colleagues weren’t able to put live chimps into the scanner. They had to submerge chimp skulls in water, then create an image of the water inside the skull as if it were the brain. Then those images and the human counterparts were merged. The comparison showed that there were five main areas of the brain that have expanded in humans since our lineage split from that of the chimps. Three were more promi- nent on the right side of the brain than the left. To complicate things further, Falk compared these mod- ern skulls with an array of fossil skulls of human ancestors and saw that these key areas of difference gradually became more prominent as the human line moved toward the present and left the chimps behind. It would be tempting to correlate these two studies. Did a set of highly active brain genes in humans lead to bigger — or at least lumpier — brains? But it’s way too early to be confident of that. And there are still major questions to be answered: What are the genes actually doing? What are these brain areas doing? How important is it that some areas of the brain are enlarged? It’s a start and it’s reassuring that brain differences have been found; after all, that’s where we differ most significantly from chimpanzees. But in the end, if indeed this puzzle is ev- er completely sorted out, these early results will only be a small part of the solution. Jay Ingram hosts the program @discovery.ca on the Discovery Channel. Jay Ingram Chimps, us and brain differences On Friday, astronomers using the Canada-France-Hawaii Telescope (CFHT) announced that they had dis- covered 11 more moons orbiting Jupi- ter, the largest planet in the solar sys- tem. This brings to 39 the total number of natural satellites known to accompany the giant planet. The 3.6-metre CFHT is equipped with the largest digital camera in the world, a monster with 140 million pix- els. This means it can image a large ar- ea of the sky in a single exposure, ide- al for searching for faint moons orbiting distant planets. The procedure is to take several im- ages of the region around Jupiter, then have a computer examine each of millions of star images on them for faint specks that move like moons of Jupiter ought to move. The suspects are then examined carefully to con- firm the discovery, which takes a cou- ple of months. Two years ago, the same procedure with the same tele- scope was used to find the previous 11 moons of Jupiter. Several recent com- puter and equipment upgrades led to the current successful attempt. The new moons are the smallest yet found orbiting any planet, just two to four kilometres wide. They take be- tween 557 and 773 days to orbit Jupi- ter. Nothing is known about their sur- face properties but they are presumed to be rocky objects like the asteroids. The discovery places Jupiter firmly in first place in the moon sweepstakes. Saturn has 30 known moons, Uranus has 21, Neptune eight, Mars two and Earth and Pluto one each. Researchers think all the smaller satellites were captured when Jupiter was young, possibly still in the process of condensing to its present size from a more bloated stage that existed more than 4 billion years ago, soon af- ter the solar system formed. There are two leading theories for the capture process. In the gas-drag hypothesis, passing asteroids are slowed by friction with proto-Jupiter’s bloated atmosphere; those that don’t burn up in the atmosphere are trapped in looping orbits like those of the new- found satellites. In the mass-growth hypothesis, the rapid growth of Jupi- ter as it gains mass from the primordi- al nebula leads to gravitational cap- ture of nearby objects. After their capture — perhaps even billions of years later — some of these bodies collided and smashed each oth- er into smaller pieces, which could ac- count for some of the small moons seen today. Evidence for this is that many of the new-found moons travel in suspiciously similar orbits. The four largest moons of Jupiter were discovered by Galileo in 1610, within months of the invention of the telescope. Each is about the size of Earth’s moon. The remaining moons are much smaller bodies. One was found in 1892 when an astronomer spied it while looking through a large telescope. All the other moons were detected during the past 98 years by photography or electronic imaging. Terence Dickinson is editor of Skynews magazine and the author of several books for backyard astronomers. Jupiter has nine-moon lead in satellite race The Universe TERENCE DICKINSON 1 A16 THE TORONTO STAR Sunday, May 19, 2002 COMPOSITECMYK A16 SUNDAY ON !SU0190502ONA016Q! Gator aids The nerve-packed bumps on the jaws of this hatchling alligator are so sensitive they can detect ripples from a single drop of water, says a new study by Daphne Soares, who recently finished work toward her doctorate at the University of Maryland. Half-submerged alliga- tors rely on the sensory array to pin- point splashes, whether caused by a fallen hatchling or an animal stoop- ing for a drink. “These are armoured creatures but they have developed this elegant way to be sensitive to their environment,” Soares says. AP FILE PHOTO
Transcript of A THE TORONTO STAR Sunday, May 19, 2002 n SCIENCE If only ... · ed target with a coded radio...
Product:STAR Date:05-19-2002Desk: NEW-0016-CMYK/18-05-02/20:06:18
n SCIENCE
BY IAN STEERSPECIAL TO THE STAR
WHEN A BOMBdropped by a U.S. AirForce F-16 blastedAlpha Company, 3rdBattalion, Princess
Patricia’s Canadian Light Infantry inAfghanistan a month ago, killing fourmen and wounding eight, some sci-entists and many World War II veter-ans and buffs wondered why therewas no IFF.
IFF stands for Identify Friend orFoe, an electronic device invented byBritish boffins more than 60 yearsago to prevent just such accidentshappening.
The first IFF units were developedin conjunction with the first radarunits, says Richard Rohmer, formerRCAF fighter pilot, retired major-general and a best-selling author.
“Without those radars,” saysRohmer, “the war might well havebeen lost because RAF Spitfires andHurricanes would not have been ableto intercept the oncoming hordes ofJu-88s and Me-109s. What IFF didwas allow allied pilots, coming backfrom raids over France, to let thosesame radars know our aircraft werefriendlies, thanks to a little blackbox.”
The principle behind the first IFFdevice — and all IFF units since —was simple. It challenge d the intend-ed target with a coded radio signal. Ifthe target had the required IFF re-ceiver/transmitter and decoder/en-coder, it “authenticated” the target byreturning the correctly coded IFF re-ply. Targets that didn’t so respondwere presumed hostile.
“IFF systems cannot do more thansort out the friendlies, ” Rohmer says.
So none can tell (independently)actual foes from merely unknownand possibly innocent targets, includ-ing allied friendly forces without theright IFF or even one’s own forces
with malfunction-ing IFF.
The newest IFFsystems use radarsor lasers, as well asradios. There aredifferent IFF sys-tems for the airforce, army, navyand marines and,of course, differentsystems for differ-ent countries. Few
of the dozens of systems now in useare directly compatible. Getting dif-ferent allied forces — as in NATO,the Persian Gulf War and Kosovo —with different systems to work to-gether and yet avoid such friendlyfire incidents is a serious, ongoingchallenge.
Even the U.S. Army’s own troopsdo not generally — and until recently,did not at all — have any way to sig-nal an errant air force or navy aircraft(the ones with the bombs) that theyare friendly. What our troops need,then, is a ground-portable version ofthe IFF system used by bombers.
Within days of the accident, Ste-phen Trimble of Aviation Week &Space Technology magazine report-ed on the U.S. Army’s newest,
ground-based IFF unit. The first mostCanadians heard of the new system,known as the Enhanced Position Lo-cation and Reporting System(EPLRS, pronounced ee-plars), wasan April 23 report by The Star’s Jo-seph Hall.
“If it works as advertised, you’dthink EPLRS is something you’dwant to include in your minimum kitlist,” says Jason Frye, a former para-trooper who served with the PPCLIand is now a Metro Toronto police of-ficer. “One per platoon would be anecessity if you’re in a battlefield.”
EPLRS is more than an IFF system.Made by Raytheon Systems, it is aUHF radio a mere 25 centimetreswide, 35 cm long and 13 cm high. It’shighly portable, weighing only 12 ki-lograms, batteries included. Theunits fit in tanks and trucks and canbe carried by paratroopers.
Being UHF radios, EPLRS unitscan, through a central control knownas a master station, exchange IFFhandshakes with aircraft like the
F-16. Airborne IFF signals are UHF,too. A secondary benefit of transmit-ting at such high frequencies is theiruse for sending high rates of data,like the position and location offriendly troops and units, reportingin a second-by-second system even inthe midst of battle.
EPLRS grew out of the PLRS, thePosition Location Reporting System,still used by the U.S. Marine Corps.First tested in the late 1970s, the Ma-rines had about 2,000 PLRS radiosand 35 of the required master sta-tions by the late 1980s.
Work began on the U.S. Army’snew, enhanced PLRS in the early1990s. Using VHSIC (Very HighSpeed Integrated Circuits), similar tothose found in today’s computersand COTS (Commercial Off-The-Shelf ) technologies, they tripled per-formance for half the cost.
With just one of these portable ra-dios and a master station at theirbase camp in Kandahar, a companyof 12 troops (like Alpha Company)
could travel up to 10 kilometres frombase camp (about the distance theywere) and have their location knownat all times and protected from acci-dental attack.
What’s amazing is that a full divi-sion of 10,000 to 20,000 troops, de-ployed with up to 1,500 radios avail-able per master station, can cover upto 150,000 square kilometres, an areaone-quarter the size of Afghanistan.Networked together, the radios notonly protect, they also form a wire-less WAN (Wide Area Network),through which the newest versionscommunicate at speeds fast enoughto allow video conferencing and “liveeye” aerial views through unmannedaerial reconnaissance vehicles of“enemies behind the hill.”
By 2000, the U.S. Army had at least2,000 of these radios. Another 3,000are either delivered or on order andover the next few l years, total salesfor all services and allies is expectedto reach 30,000. Thanks to Jane’s In-formation Group, perhaps the pub-lic’s best source of military informa-tion, we also know at least someEPLRS units, and/or their PLRS pre-decessors ( just as capable IFF-wise)were deployed to the Persian GulfWar, Bosnia and elsewhere. It is hardto believe such systems are not nowserving U.S. forces in Afghanistan.
As retired Maj.-Gen. Lewis Mac-Kenzie, who commanded U.N. forcesin Bosnia and once commanded thePPCLI, says: “If members of theAmerican brigade (part of the U.S.101st Airborne Division) our Canadi-an troops are attached to have accessto this equipment, then certainly theequipment should have been provid-ed to our troops as well.”
EPLRS radios are not currently inservice and have not been orderedfor Canada’s defence forces, con-firmed Lt.-Cmdr. Phil Anido, spokes-person for acquisitions at NationalDefence headquarters in Ottawa.Why? “Partly because of money.”
According to Jane’s, 6,000 such ra-dios could earn Raytheon $450 mil-lion. So they could cost somethinglike $75,000 each. That doesn’t in-clude service and spare parts, or theoptional PC Ruggedized Laptop,probably around $75,000 itself. For alaptop? Yes, because “ruggedized” ismilitary-speak for “bulletproof” andinside is a National Security Agencymicro-miniature supercomputer, ca-pable of scrambling and unscram-bling coded communications that areotherwise unbreakable, includingIFF.
With no plan to outfit Canada’sforces, other more immediate op-tions might be to buy or borrow a fewnew EPLRS radios from the U.S. Ar-my or buy some used PLRS radiosfrom the Marines.
“The solution could be as simple asmerely attaching a couple of guysfrom U.S forces with these radios toserve with our Canadian troops,”MacKenzie says.
Asked about EPLRS in the Houseof Commons, Defence Minister ArtEggleton replied: “It’s not being usedin this particular operation yet.”
Ian Steer is a Toronto freelancer.
If only they’d had an IFF
PHOTO COURTESY OF RAYTHEON SYSTEMS
LAVISH LAPTOP: A U.S. soldier demonstrates the EPLRS radioidentification device and the “ruggedized” laptop, compatiblewith IFF systems. Below, a laptop screen displays friendlytroops (blue Xs) and possible foes (red triangles).
Modern version of a World War II devicecould probably have prevented
‘friendly fire’ tragedy in Afghanistan
‘If it works asadvertised, you’dthink EPLRS issomething you’dwant to include inyour minimum kitlist.’wJASON FRYE,
former paratrooper
One of the most intriguing puzzlesthat the unravelled human genomemight solve is the difference be-tween us and chimps. If you look atthe genetics of both, there is a scant1.5 per cent difference. But surely,for all the humanness of chimps, thegulf between the two species shouldbe much, much wider than that.What gives?
First things first. Measuring per-centages of genetic difference be-tween species is misleading. If thechimp comparison startles you, howabout the fact that the ordinarymouse shares about 95 per cent of itsgenes with us? Pick a mammal —any mammal — and it will share allkinds of genes and groups of geneswith us, most of them concernedwith the basic housekeeping of amammalian body.
Add to that the fact that genesdon’t correlate one-to-one with anat-omy. Dozens of genes are employedsimply to maintain the ability of ourblood to clot when we’re cut and weshare those genes — or ones verymuch like them — with tigers,whales and anteaters. On the otherhand, a single gene can regulate theactivity of several others. And alter-ing a gene like that can change theshape and size of an animal. Somatching genes between animals isa misleading exercise to begin with.
Even so, the 1.5 per cent differ-ence between chimps and humans isstill puzzling and important, wheth-er you want to emphasize our differ-ences or reaffirm our similarities.Two recent studies have addressedthis subject and they show just howfar away we are from understandingwhat’s going on.
The first was a study published afew weeks ago that took a first stabat identifying differences in gene ac-tivity between the two species. Us-ing tissue samples from humans andchimps that had died of naturalcauses, the researchers found thatthe genes from both were equally ac-tive in the blood and liver but the hu-man genes were much more activein the samples of brain tissue. Itwasn’t a case of gene difference butgene productivity. So these differ-ences, which might be crucial to thespecies disparity, wouldn’t evencount as part of the 1.5 per centdifference.
There were two interesting side-lights to this research. One, that twomouse species as genetically distantfrom each other as we are fromchimps showed no such brain differ-ences. That just reaffirms that some-thing happened in our brains overthe last few million years that sets usapart from the chimps. The secondpoint is that these are all averages;surprisingly, the gene activity in oneof the human samples was actuallywithin the chimp range.
A second chimp/human study wasjust released by neuroscientist DeanFalk of Florida State University. Insomething of a technological tour deforce, she overlaid 3-D brain imagesof chimps and humans to get an ideawhere the significant differenceswere.
It was tricky work because Falkand her colleagues weren’t able toput live chimps into the scanner.They had to submerge chimp skullsin water, then create an image of thewater inside the skull as if it were thebrain. Then those images and thehuman counterparts were merged.
The comparison showed thatthere were five main areas of thebrain that have expanded in humanssince our lineage split from that ofthe chimps. Three were more promi-nent on the right side of the brainthan the left. To complicate thingsfurther, Falk compared these mod-ern skulls with an array of fossilskulls of human ancestors and sawthat these key areas of differencegradually became more prominentas the human line moved toward thepresent and left the chimps behind.
It would be tempting to correlatethese two studies. Did a set of highlyactive brain genes in humans lead tobigger — or at least lumpier —brains? But it’s way too early to beconfident of that. And there are stillmajor questions to be answered:What are the genes actually doing?What are these brain areas doing?How important is it that some areasof the brain are enlarged?
It’s a start and it’s reassuring thatbrain differences have been found;after all, that’s where we differ mostsignificantly from chimpanzees. Butin the end, if indeed this puzzle is ev-er completely sorted out, these earlyresults will only be a small part ofthe solution.
Jay Ingram hosts the [email protected] on the DiscoveryChannel.
Jay Ingram
Chimps, usand braindifferences
On Friday, astronomers using theCanada-France-Hawaii Telescope(CFHT) announced that they had dis-covered 11 more moons orbiting Jupi-ter, the largest planet in the solar sys-tem. This brings to 39 the totalnumber of natural satellites known toaccompany the giant planet.
The 3.6-metre CFHT is equippedwith the largest digital camera in theworld, a monster with 140 million pix-els. This means it can image a large ar-ea of the sky in a single exposure, ide-al for searching for faint moonsorbiting distant planets.
The procedure is to take several im-ages of the region around Jupiter,then have a computer examine eachof millions of star images on them forfaint specks that move like moons ofJupiter ought to move. The suspectsare then examined carefully to con-
firm the discovery, which takes a cou-ple of months. Two years ago, thesame procedure with the same tele-scope was used to find the previous 11moons of Jupiter. Several recent com-puter and equipment upgrades led tothe current successful attempt.
The new moons are the smallest yetfound orbiting any planet, just two tofour kilometres wide. They take be-tween 557 and 773 days to orbit Jupi-ter. Nothing is known about their sur-face properties but they are presumedto be rocky objects like the asteroids.The discovery places Jupiter firmly infirst place in the moon sweepstakes.Saturn has 30 known moons, Uranus
has 21, Neptune eight, Mars two andEarth and Pluto one each.
Researchers think all the smallersatellites were captured when Jupiterwas young, possibly still in the processof condensing to its present size froma more bloated stage that existedmore than 4 billion years ago, soon af-ter the solar system formed.
There are two leading theories forthe capture process. In the gas-draghypothesis, passing asteroids areslowed by friction with proto-Jupiter’sbloated atmosphere; those that don’tburn up in the atmosphere are trappedin looping orbits like those of the new-found satellites. In the mass-growthhypothesis, the rapid growth of Jupi-ter as it gains mass from the primordi-al nebula leads to gravitational cap-ture of nearby objects.
After their capture — perhaps even
billions of years later — some of thesebodies collided and smashed each oth-er into smaller pieces, which could ac-count for some of the small moonsseen today. Evidence for this is thatmany of the new-found moons travelin suspiciously similar orbits.
The four largest moons of Jupiterwere discovered by Galileo in 1610,within months of the invention of thetelescope. Each is about the size ofEarth’s moon. The remaining moonsare much smaller bodies. One wasfound in 1892 when an astronomerspied it while looking through a largetelescope. All the other moons weredetected during the past 98 years byphotography or electronic imaging.
Terence Dickinson is editor of Skynewsmagazine and the author of severalbooks for backyard astronomers.
Jupiter has nine-moon lead in satellite raceThe Universe
TERENCE DICKINSON1
A16 THE TORONTO STAR Sunday, May 19, 2002
COMPOSITECMYKA16 SUNDAY ON !SU0 190502ON A 016Q!
Gator aidsThe nerve-packed bumps on thejaws of this hatchling alligator areso sensitive they can detect ripplesfrom a single drop of water, says anew study by Daphne Soares, whorecently finished work toward herdoctorate at the University ofMaryland. Half-submerged alliga-tors rely on the sensory array to pin-point splashes, whether caused by afallen hatchling or an animal stoop-ing for a drink. “These are armouredcreatures but they have developedthis elegant way to be sensitive totheir environment,” Soares says.
AP FILE PHOTO
