From Max Michaelis, University of Natal
South Africa
As one of the first civilian scientists to propel tiny objects with Britain’s
most powerful laser over twenty years ago, I would like to compliment New
Scientist on bringing the topic of laser impulse space propulsion (LISP) to
a wider readership
(“On wings of light”, 10 January, p 34).
Leonard David captures the enthusiasm of the leading American scientists in
starting to develop what has to be a more intelligent and eco-friendly way of
getting into space. The laser “fuel” can indeed be ice or air, and even if it
isn’t, laser launching will require some twenty times less fuel than
conventional chemical rockets. (Each shuttle launch “liberates” tonnes of
noxious chemicals into the atmosphere.)
But why only mention Leik Myrabo? There are dozens of eminent laser
scientists working in the field of laser ablation. And what of other nations?
Clearly David never asked anyone, say, at Livermore, or in Britain at the
Rutherford Laboratory Central Laser Facility.
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Also Myrabo’s “air-breathing” stage can only be a first (though very useful)
step in getting out of the atmosphere. The major energy contribution has to
happen in space, which is why LISP will have to be done from a high mountain.
Otherwise you “lose sight” of the target. And lower atmospheric air is never
clear enough for long-distance transmission of laser beams.
Could not one of Ian Whadcock’s attractive drawings have been replaced with a
box containing such facts as that the great German engineer Erwin Saenger
invented light propulsion some fifty years ago?
Finally, might I mention that the South African physicist Andrew Forbes and
his colleagues obtained very similar propulsion results to Myrabo’s using the
uranium isotope separation laser at Pelindaba. This was a “fun” experiment and
is reported here for the first time.
Given that laser launching will have to be from a high mountain top
(preferably on the equator since most useful trajectories are equatorial), and
that a poor climate excludes Chimborazo in Ecuador, I leave it to New
Scientist readers to work out which extinct African volcano may one day
become an international space centre.
