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25 February 2008

A Shot In The Dark

The US claims that destroying one of its defunct satellites with a missile was necessary for the hazard its toxic fuel posed to life on Earth. It's an understatement that the world isn't convinced; neither are American experts. Here is an exposition of a six-week (perhaps more) long drama

Keep aside the game of American and international politics surrounding the recent shooting down of a defunct spy satellite by the US; the logistics and science involved in the exercise was simply fascinating. Once, not giving two hoots to international concern, the US Administration gave the order to demolish with a missile the 'dead' National Reconnaissance Office satellite, the Department of Defence needed to re-programme the weapons -- outfit three Navy cruisers, the USS Lake Erie, USS Decatur and USS Russell, with remodelled Aegis anti-missile defence systems and a total of three SM-3 missiles -- within a few weeks.

The confusion:
Too many cooks spoil the broth, they say. Much before the event and its prior plan caught the media's attention, the US Administration had summoned a high-powered team of 200 personnel -- Navy scientists, missile defence experts, the makers of the Aegis system and RIM-161 Standard Missiles-3 (Lockheed Martin and Raytheon respectively), as well as scientists from the Johns Hopkins University Applied Physics Laboratory -- to study the feasibility of shooting down the satellite with a missile. Notable sub-contractors and technical experts in the team also included Boeing, Alliant Techsystems, Honeywell, Naval Surface Warfare Centre and the Massachusetts Institute of Technology's Lincoln Laboratory.

The resultant report was a labyrinth of 'if's and 'but's. Should the satellite be shot down at all? If yes, can the American 'shooters' pull it off? On record, Lt Gen Carter Ham, director of operations for the Joint Chiefs of Staff, had opined on January 15 that it was difficult not only to hit the satellite but even to know the best time to shoot.

Mr David Wright, a senior scientist at the suggestively named Union of Concerned Scientists, had said that he would put the odds of a successful intercept at no better than 50 per cent. And he expressed concern that debris from a successful strike could harm other objects in relatively low orbits.

What if the first attempt failed? What if that attempt, despite failing to achieve a head-on collision with the fuel tank, were to deflect the falling satellite so much that the calculation of the new trajectory of its fall, for a possible second attempt to hit it, becomes terribly difficult? Moreover, officials wanted Atlantis voyage to be home to avoid the risk of being hit with the shot satellite's debris.

The most complicated of all problems was customising the Aegis system and compatible missiles. The technologies were originally designed to intercept ballistic missiles using heat sensors, but the spy satellite was cooler in temperature. To account for this difference, the three SM-3s needed new software, hardware, sensors and the launching systems, too, had to be given new sensors and software updates. Further, it would take a large crew of engineers to rewrite the code, debug it, and test it over and over again before the bus-sized satellite would fall (on our head?) in March.

It eventually took President George W Bush on January 4 to order what some experts are calling the "crash programme", though till as late as January 15, the US's defence sources that could be contacted by the media maintained an impression that it was all a tentative project. Granting them their right to secrecy, let's see how the American Administration went about it.

The plan and the apparatus:
It was planned that the Lake Erie, a cruiser that has participated in a dozen, mostly successful, tests to intercept mock enemy missiles in flight over the past six years, would take the first shot at the satellite at a distance of more than 240 km, just beyond the reach of Earth's atmosphere. And the SM-3 missile aboard the Lake Erie, equipped with a heat-seeking sensor modified in order to enable it to zero in on the satellite, whose heat 'signature' is smaller than that of a ballistic missile in flight, would hit the satellite.

Since the Aegis Ballistic Missile Defence System (alternatively called Sea-Based Midcourse) is designed to intercept ballistic missiles post-boost phase and prior to re-entry, it was ideal to shoot down the falling satellite which, in effect, was like a ballistic missile that leaves Earth's atmosphere only to return to hit enemy targets.

The SM-3 is a ship-based anti-ballistic missile which has been employed on several occasions in the past to shoot down defunct satellites. The US has been shooting them down since the 1980s, an era when the media was not as hyperactive, though this missile is newer. The SM-3 is not only used by the US Navy but also operated by the Japan Maritime Self-Defence Force.

Six teams were placed across the US to be prepared for rescue efforts -- the spacecraft contained 1,000 pounds of hydrazine in a tank that could have survived air-friction while re-entering Earth's atmosphere, and a fuel tank liner made of beryllium -- lest the satellite hit any spot on American territory. It is for the reader to judge from the following section how much of the scare scenario was real and how much of it was hyped.

Hydrazine is a chemical of considerable military interest widely used as a rocket fuel and as a propellant for gas turbine generators. Exposure to high levels of hydrazine may lead to irritation of the eyes, nose, and throat, dizziness, headache, nausea, pulmonary oedema, seizures and coma in human beings. Worse, acute exposure can also damage the liver, kidneys, and central nervous system. The liquid is corrosive and may produce dermatitis from skin contact in humans and animals. At least one human being is known to have died from exposure to hydrazine hydrate.

As for beryllium, exposure to it would be less dangerous. Beryllium can be harmful if you breathe it. High exposure results in a condition that resembles pneumonia. Up to 15 per cent of people may develop inflammation in the respiratory system many years after the exposure. It would make them feel weak and tired, and can cause difficulty in breathing. It can also result in anorexia, weight loss, the heart enlarging towards the right side and heart disease in advanced cases. However, some people who are sensitised to beryllium may not experience any symptoms. And swallowing beryllium has not been reported to cause effects in humans because very little beryllium is absorbed from the stomach and intestines.

So, the US Federal Emergency Management Agency prepared a guide for the rescue teams that included information like above about the toxic chemicals. The agency warned officials not to pick up any debris or provide mouth-to-mouth resuscitation to anyone who has inhaled hydrazine or beryllium.

The preparedness:
Within two weeks of the January 4 order, the aforementioned US warships were fitted with modified Aegis anti-missile systems, the ships' crews were trained for an unprecedented mission and three SM-3 missiles were pulled off an assembly line and given a new guidance system.

The expanse of the 'laboratory' was not limited geographically to the US mainland in North America. The exercise involved ships and radar sites in the Pacific to high-powered telescopes in Hawaii and elsewhere to a specially fitted Air Force plane and a Navy ship that snoops on missile tests, as Aegis BMD equipped vessels would transmit their target detection information to the ground-based Mid-course Defence system, and engage potential threats using the SM-3, spread across this entire area.

The execution:
Only one missile was finally fired last Thursday, but the other two had to be ready, in case a second or third attempt was needed, howsoever precarious those latter attempts would have been. The Erie was accompanied by the Decatur and the Russell somewhere (the exact location hasn't been disclosed) in the Pacific Ocean north of the equator. The Decatur fed trajectory information to the Erie, and the Russell backed up the Decatur. As it turned out, the altitude at which an SM-3 hit the satellite was lower than what was pre-determined -- about 209 km above the Earth surface.

The Erie launched the attack at 08.56 am IST on February 21. It hit the satellite as the spacecraft travelled at more than 27,000 km/h. As the satellite was orbiting at a relatively low altitude at the time it was hit by the missile, some debris re-entered Earth's atmosphere immediately and the rest will keep falling for more than a month hence.

The cost:
With each SM-3 costing about $10,000,000, the tab for the munitions alone must have added up to almost $30,000,000, though Lt Gen Ham declined to divulge the overall expenditure. Two weeks ago, Pentagon officials had estimated the cost to be between $40,000,000 and $60,000,000. The customising of the Aegis system and missiles for the satellite mission had already incurred major costs. One may guess how much Raytheon and Lockheed Martin fleeced the American exchequer and what fortunes were made by the engineers who rewrote the code, debugged it, and tested it repeatedly, with some tests that might have been aimed at inflating their pay-cheques.

The stakes were even higher than what is incurred in a commercial software launch, as the system had to work perfectly in a 10-second window. There was no opportunity to fix problems with software patches later on (before this week's launch, the same anti-missile system had been successful on eight out of 10 attempts).

To what avail?
From a typical Indian point of view, the toxicology appears too far-fetched to merit such a gargantuan programme. For sure there are more people in the world who think like us, Indians. US officials had said that the hydrazine would have posed a potential health hazard to humans had it landed in a populated area, and now they can't say for sure if the red herring, or whatever, of hydrazine has actually vanished in thin air.

The odds of the 'accident' did not demand the experiment. But even if Pentagon had chosen not to shoot down the satellite, it thought it was worth trying to eliminate the chance. Throughout the lengthy drama, China, which had carried out a satellite destroyer test last year, said little more than "we're keeping a watch". Russia expressed its discomfiture more forthrightly. As for India, a tense atmosphere, too, looks amusing when you are not a party to the dispute.

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Surajit Dasgupta treats no individual, organisation or institution as a holy cow.