Monthly Archives: December 2009

Predictions and Wishes

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At a recent speaking engagement, I was introduced as an “expert”.  Scary title, that.  At another place I was introduced as “highly experienced”  which is a polite way of saying “old”. 

 

These put me in mind of Clarke’s Law.  Sir Arthur C. Clarke, the inventor of the geostationary satellite, author of innumerable books both non-fiction and science-fiction, and one of the truly forward thinkers of the 20th century.  Clarke’s first law has to do with predictions and experts.  He came to an interesting conclusion after studying the predictions of experts over the previous centuries.  To get you in the right frame of mind, consider some of these real predictions by well respected experts of the past:

 

Rail travel at high speeds is not possible because the passengers, unable to breathe, would die of asphyxia – Dr. D. Lardner, 1835

 

I can accept the theory of relativity as little as I can accept the existence of atoms and other such dogmas – Ernst Mach 1912

 

Our future discoveries must be looked for in the sixth decimal place – Nobel Prize laureate A. A. Michelson, 1894

 

Aerial flight is one of that class of problems with which man will never be able to cope – Simon Newcomb, 1903

 

The [atomic] bomb will never go off, and I speak as an expert in explosives – Adm. William Leahy to President Truman, 1945

 

The popular mind often pictures gigantic flying machines speeding across the Atlantic carrying innumerable passengers in a way analogous to our modern steam ships.  It seems safe to say that such ideas are wholly visionary and even if the machine could get across with one or two passengers, the expense would be prohibitive to any but the capitalist who could use his own yacht. – William H. Pickering, 1910

And so on.  You get the point, and there are plenty of other predictions we can laugh at today. 

 

So Clarke postulated his first law: 

 

“When a distinguished but elderly scientist states that something is possible, he is almost certainly right.  When he states that something is impossible, he is very probably wrong.”

 

 

Everybody is making up Christmas lists or maybe New Year’s Resolutions and wishes for what might happen in 2010 or later.  I think I will avoid such lists. 

 

In hopes of proving Sir Arthur Clarke correct, and based on my status as an aging “expert”, I would like to make some predictions (tongue firmly planted in cheek – hoping that reverse psychology will make the predictions fail):

 

1.  Human spaceflight was a passing fancy and its disappearance will hardly be noted by historians nor missed by the general public.

 

2.  Human beings will never again set foot on the moon nor travel to Mars or any other celestial body.

 

3.  The study of engineering and technology will become a thing of the past as the world’s standard of living returns to that of the 18th century.

 

4.  The popular entertainments of the day will so capture the imagination of the public that they are rendered incapable of any real productivity and spend their time in the pursuit of gossip about actors and sports figures.

 

5.  Constant exposure to digital toys will decrease the human attention space to milliseconds preventing any useful thought or accomplishment.

 

6.  Without any unifying goals, the world becomes increasingly balkanized into clan-like groups who turn to violence over ancient insults, real or imagined.

 

OH NO.  What an awful set of predictions.   The Grinch or Ebenezer Scrooge could not have done better.  But there they are, and I want credit for having made them.  If they come true, then I should be remembered for having predicted them.  If they don’t come true, I’ll be just as happy to join the company of William Pickering and A. A. Michelson!

 

Now for what I really wish for at this season  (not a prediction, lest I jinx it!):

 

A commitment from all the space faring nations of the world to join together – with adequate resources – to explore in detail the entire solar system in our lifetime; including the first permanent human habitations (colonies) on the Moon and Mars and outposts at other strategic points in the solar system; a well established and effective transportation system to link this community together; and a strong technology development program to enable it all.  Such an international effort would unite the peoples of the earth in cooperation to achieve a historic and noble goal and would result in innumerable benefits from technology and medical advancements, stronger economies and new industries, and serve to inspire our children to study the hard subjects and to follow their parents in achieving great things.

 

This may be too much to wish for; some may call it unrealistic, but human progress has only been truly made by unrealistic people.  Now my wish is that we buckle down and do it!

 

My very best wishes for each of you to have a Merry Christmas and Happy New Year!

Time to Closest Approach

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Being at a conference on Orbital Debris has turned my thoughts back to being a Flight Director and experiences I would rather forget.

There is a lot of junk in earth orbit, and some of it endangers our astronauts every day.  Paint flecks and particles of solid rocket exhaust are big enough to damage the shuttle windows.  We now replace the shuttle windows every flight because of the damage that these microscopic particles cause. 

At 5 miles per second, there is a lot of energy in “collisions” between orbiting objects.  Every bit of space junk packs the equivalent of 25 times its weight in TNT because of the extreme speeds of orbital encounters.  We cannot track the small stuff.  Even pieces as big as loose bolts are untrackable and potentially fatal.  A one inch bolt in orbit could punch a hole right through the shuttle or the station causing huge damage and explosive decompression.  You don’t even want to think about what it would do to a spacewalker in their fabric suit.

Larger items are tracked by NORAD (they have a new name but I never remember it).  We know where the big pieces and can avoid them.  Or so you might think.  There are limits to how accurately the trajectories of space junk can be determined.  Trajectories are affected by the solar wind, transient and unmonitorable variations in the upper atmosphere, and some objects even have propulsive vents so their trajectories are constantly and irregularly changing. 

The shuttle, of course, is always maneuvering and changing attitude.  The shuttle thrusters are not completely symmetric so there are small changes to the shuttle’s trajectory every time they fire. 

Orbital trajectories are predicted into the future assuming none of these variations.  Even so, the very small uncertainties in a trajectory  gets multiplied over hours of prediction and this leads to a grey zone surrounding its predicted future position where the space object may or may not be.

Nowadays this is a sophisticated science with much better tools.  Better radars and lots of mathematics and probabilities give a much more complete notion of where and when encounters may take place. 

In the early days of shuttle we just knew that anything predicted to come within a few miles could be a hazard.  Missing by inches is OK; missing by a mile is good; but it was all like Russian roulette in those days.

Knowing how to maneuver to avoid a predicted “conjunction” is critical.  If you guess wrong and maneuver to the part of the uncertainty box where the space junk actually is: POW.  Sometimes doing nothing is the best option.

Operationally there are other impacts.  Since shuttle maneuvers are initiated by the crew, obviously the crew must be awake to maneuver the ship.  If the crew sleep is interrupted, their performance the next day may be affected.  Think about being awakened in the middle of the night to do a precise task and then trying to go back to sleep, wake up the next morning at the regular time, and have a big work event that day.  Not really good.

So the early shuttle it was thought that we should not wake the crew up for debris avoidance maneuvers.  Even though space junk was predicted to be coming close by and could hit us, the odds were in our favor for a miss.  In the cold calculation of the risks involved it was thought better to let the crew sleep rather than wake them for something that might not happen.  We codified this in the Flight Rules.

On exactly three occasions I was the Flight Director on the crew sleep shift when we got the word a “conjunction” was imminent.  I remember each event like it was yesterday with crystal clarity.  Some things do not leave you.  I made all the appropriate notifications; phone calls to the management confirmed that we should follow the rules, let the crew sleep, and bet on the odds in our favor.

So GC would set a clock on the big board counting down to “TCA”.  Meanwhile we all tried to do the mundane work of monitoring the shuttle systems and planning the crew’s activities for the next day.   On the assumption that there would be a next day. 

 But as the clock counted down close to zero, Mission Control would get very quiet.  We all knew what might happen.  It’s tough to sit on your hands when your friends are in danger and you can’t do anything about it. 

In my imagination, the worst case scenario played out:  instantaneous cessation of telemetry transmission from the shuttle followed some time later by NORAD tracking confirming a multiple pieces in an orbit where only the shuttle had been before.  Then the notifications, the investigations, the whole drawn out parade of mourning and recrimination.  I could see it all. 

So as we waited for the clock to count to zero, there was plenty of time to contemplate metaphysical topics:  life, death, courage, risk, achievement, probability, dishonor.  They are all fellow travelers, intimately bound together.  No great accomplishment comes without difficulty or risk.  Miscalculation or failure results in death and dishonor.  But it is what it is; you do the best you can, make the best rational choice you can given what you know, and then wait for the result. 

Going to Las Vegas holds no enticement for me.