Never Mind the Bullocks, Here's the Science (17 page)

For our astronauts, the net result is simple – free fall. After one second of falling, they are still the same distance from the surface of the Earth.

Why Zero Ain’t Really Zero

They are in ‘free fall’. They are always falling freely—but thanks to the perfect matching of their speed and the curve of the Earth, they are always the same distance from the surface of the Earth.

A few centuries ago, Isaac Newton considered this problem of ‘free fall’ by what scientists call a Thought Experiment. He thought about a cannon mounted (say) 1 m above the ground. If it had a small charge of gunpowder, the ball would fly 100 m before gravity pulled it down and it hit the ground. A bigger charge would make it fly 100 km before it hit the ground. An absolutely huge charge
would make it fly 1 m above the ground all the way around the Earth (assuming that there was no wind resistance). If there were no wind resistance, the cannonball would orbit the Earth forever.

So, like the astronauts, the cannonball would always be falling. But, again, there’s the perfect match of its speed and the curve of the Earth. So it’s always falling toward the Earth, and the surface of the Earth is always dipping away from it.

Vomit Comet

The ‘Vomit Comet’ was the name given to the aeroplanes operated by the NASA Reduced Gravity Research Foundation. By flying in a series of up-and-down curves, each about 10 km long, the pilots can generate about 25 seconds of effective weightlessness for every 65 seconds of flight. Of course, there’s no such thing as a free lunch, so the 25 seconds of weightlessness are balanced by a similar period of double gravity.

The name Vomit Comet arose because, under these trying conditions, about one-third of passengers vomited a lot, about one-third were just nauseated and felt like vomiting, and about one-third were unaffected.

The first NASA Vomit Comet was a Lockheed C-131. After its retirement from service in 1959, it was replaced by two KC-135 Stratotankers. One, NASA 930, was used to film weightlessness sequences for the movie
Apollo 13.

Today, several commercial operators now offer the sensation of weightlessness.

In 2005, NASA began using a C-9B Skytrain II. And NASA renamed it with the ‘nicer’ nickname of ‘Weightless Wonder’ rather than ‘Vomit Comet’.

‘Weightless’

Suppose you are standing on your bathroom scales. Gravity pulls you down onto the scales. The scales are, in turn, resting on the bathroom floor. They ‘push’ back up, allowing you to register a certain weight on your scales.

Now, let’s try this experiment but in a different location. There are several ‘Free Fall Facilities’ around the planet. NASA has the Zero Gravity Research Facility at the Glenn Research Center in Cleveland, Ohio with a 145 m vertical shaft, in which an experiment can fall 132 m in 5.18 seconds. Suppose you stand on your bathroom scales on a trapdoor at the top of the vertical shaft. Your weight is (say) 80 kg. The scales register 80 kg. Then the trapdoor opens, and you and the scales (still touching each other) begin to fall. Gravity still pulls on you (which is why you fall). Your feet press on the scales. But the scales don’t press back, because they are not resting on the floor. So the scales register no weight—and you are now ‘weightless’.

You are now in free fall (just like the astronauts). Unfortunately, you don’t have a horizontal velocity of 7 km/sec. So after a few seconds you slam into the 4.5 m thick pile of expanded polystyrene pellets at the bottom of the shaft and come to a very painful halt.

We can experience a kind of free fall down here on Earth, but only for brief instances.

Free Fall on Earth

According to the
Guinness Book of Records
, the longest free fall on Earth happened to Vesna Vulovic, a flight attendant with JAT Airlines on 26 January 1972. Her aeroplane, a DC-9, exploded thanks to a bomb planted by the Ustashe (the Croatian National Movement). The DC-9, Flight JAT 367, was en route from Copenhagen to Zagreb and Belgrade.

The DC-9 broke into pieces, and Vesna fell more than 33,000 ft (10,000 m). Vesna lost all memory from one hour before the explosion to one month afterwards. She fractured her skull, suffered a brain haemorrhage and fractured three spinal vertebrae. She was initially paralysed from the waist down, but after an operation and a few months recovery, could walk again. She received her Guinness Award in London from Paul McCartney, the ex-Beatle.

But her ‘flight’ was not a true free fall. Luckily, the air resisted her fall, limiting her top speed to about 200 kph.

And the free fall of Joseph Kittinger from 102,800 ft (31.3 km) was not a true free fall. He wore a multi-stage Beaupre Parachute that opened in three stages. Its purpose was to stabilise the high-altitude parachutist, and stop him from spinning and tumbling. The first mini-parachute (18 inches or 0.5 m across) deployed within a few seconds. In turn, this pulled out a small 6 ft (2 m) drogue parachute. Finally, at an altitude of around 14,000 ft (4.2 km), the 28 ft (8.5 m) parachute would deploy fully.

In his first test jump from a high-altitude balloon on 16 November 1959, the main parachute wrapped around his neck. Amazingly, he survived his fall from 76,400 ft (23.3 km). On his second test jump on 11 December 1959, he stepped out of the gondola of his balloon at 74,700 ft (22.8 km). There were no complications. His third and final jump was on 16 August 1960. Falling from 102,800 ft (31.3 km), he experienced temperatures as low as -70°C, and speeds up to around 1,000 kph. He fell
in conditions close to free fall for 4 minutes and 36 seconds. The main parachute opened in the thicker atmosphere below 18,000 ft (5.4 km). The total fall time was 13 minutes and 45 seconds.

Joseph Kittinger, like Vesna Vulovic, was not in true free fall, as wind resistance slowed him down. He also had extra retardation from the small, stabilising drogue parachute.

Douglas Adams (in his book
Life, the Universe and Everything
) said that flying was quite easy—‘the knack lies in learning how to throw yourself at the ground and miss’. This is what the astronauts in space do—they continually fall towards the ground, and they continually miss it. It’s not ‘zero gravity’ that keeps them up there—it’s the combination of their massive horizontal speed and the curvature of the Earth.

NASA used to talk of ‘zero gravity’. Today, they talk of ‘microgravity’. Perhaps the correct approach is to realise that there is no such thing as gravity and, although the Earth may be a beautiful place, Earth’s gravity really sucks…

Zero Gravity? Moon?

The Moon is a lot further away than the astronauts on the International Space Station, so does the Earth’s gravity still affect it?

The Moon orbits the Earth at a distance of about 400,000 km. It continues to orbit the Earth because Earth’s gravity is strong enough – even at a distance of 400,000 km – to hang onto it.

So if the Earth’s gravity can hang onto the Moon, it can easily hang onto astronauts a mere 350 km away.

References

McCallum, Yoka, et al.,
Physics 2 HSC Course
, John Wiley & Sons, 2001, pp 2-12.

Young, Hugh D. and Freedman, Roger A.,
University Physics with Modern Physics
, 11th edition, Pearson Education, 2004, pp 58-59, 166-167, 459-461.

Drugs Ain’t Drugs

Antibiotics have been part of our lives since the end of World War II. Since then, the pharmacological armamentarium of modern medicine has grown in leaps and bounds. I love having access to antibiotics, and would hate to live in a world without them. On the other hand, I know that medications often have to be ‘fine-tuned’ to the individual patient.

Even so, I was quite surprised to read the statement of Dr Allen D. Roses in which he said, ‘The vast majority of drugs—more than 90%—only work in 30 or 50% of the people.’ He went on to clarify his statement: ‘I wouldn’t say that most drugs don’t work. I would say that most drugs work in 30-50% of people. Drugs out there on the market work, but they don’t work in everybody.’

At the time (December 2003), Dr Roses was worldwide vice-president of genetics at GlaxoSmithKline (GSK). Since then he has taken up a position at the Deane Drug Discovery Unit at the Duke University Medical Center in North Carolina in the USA.

Drugs Not Perfect

Here is a list of how effectively (percentage of cases) some conditions can be treated by medications:

There are plenty of good reasons why this success rate is so often way below 100%.

First, nothing that human beings have ever made is perfect. While we have been practising pharmacology for thousands of years, our modern pharmacology industry is barely half a century old, and human DNA was mapped only in the 21st century.

Second, the process by which new drugs are developed is not perfect. Typically, it takes about 15 years and $500 million to get a drug to the stage that it can be tested first on animals. These animals have been chosen to be genetically the same as each other. The drug is then tested on a relatively small group of human beings—who are each genetically different from each other. Drug toxicity at this final stage means that 90% of all drugs being developed get sidelined, never to be used. Finally, the drug is released onto the market, with careful monitoring in place to look for further side effects in the greater population.

Third, even though some of these conditions (e.g. asthma and schizophrenia) might have just a single name, the names actually cover many different conditions with different causes. The reason the different conditions have one name is that the final symptoms are very similar, e.g. shortness of breath in asthma or the inability
to be oriented in time, place and person in schizophrenia. If these different diseases have different causes, they could easily require different treatments.

Fourth, there are so many environmental variables in people that affect medications—factors such as age, gender, tobacco use, exercise regime, diet, other medications that may interact, and so on.

Fifth, and probably most importantly, there are genetic factors involved. For example, how the drug enters the circulation, how it
is transported, how it is distributed around the body and how it works at the desired site of action.

Medical doctors (the people who prescribe the drugs developed by the pharmacologists) have long known that medications are not perfect. Often, doctors will have to carefully ‘juggle’ the medications of a patient to get the best results. Another consideration is that some patients will respond quite badly, and might even suffer life-threatening complications, despite having only a very small dose of a particular medication. This rare but very serious uncertainty (which is related to allergic response) is difficult to predict.

So Many Drugs, So Few Get Through

90% of newly developed drugs are sidelined because they are toxic to a tiny percentage of the population. In the future, we hope to be able to use those drugs only on the 99.99% of people who can benefit from them, and steer these drugs away from the 0.01 % of people to whom they are toxic.

Gattaca in US Military

Genetic discrimination is the theme of the movie
Gattaca.
The letters that make up the name ‘Gattaca’ are the initial letters of the four bases (or chemical compounds) that make up the human DNA – Adenine, Cytosine, Guanine and Thymine.

Genetic discrimination is now forbidden in the USA, thanks to the passing of the
Genetic Information Nondiscrimination Act
of 2008. The Act ‘bars insurers from using the results from genetic tests to deny coverage to new applicants, or from hiking the price of premiums for existing customers. It would also make it illegal for employers to use genetic information in hiring, firing or promotion decisions.’ (Of course, this Act has no relevance in Australia, it applies solely to the USA.)

But personnel of the US military are shamefully excluded from this protection. The medical cost would not be great. About 250 US military personnel are discharged each year for medical problems that have a genetic basis, the associated cost is estimated at $1.7 million annually. It is certainly very small, when compared to the estimated cost of $600 million per day for the Iraq War, a war that began on 20 March 2003.