Category Archives: Mathematics

Mathematics, Media Criticism, Science And Society, Space, Technology and Society

Nuclear Weapons As A Unit Of Measurement

19 Comments

Some thoughts:

“In general,” he added, “What I don’t like is … the idea that kiloton or a megaton is just an energy unit, that it’s equivalent to so many joules or something. Because you could do that. You could claim that your house runs so many tons of TNT worth of electricity per year, but it sort of trivializes the notion.”

While I agree that the notion of comparing a bolide explosion to a nuclear event is misleading, I think he misses the boat himself here. It’s not just about an “energy release.” It’s about how fast the energy is released. That is, talking about megatons of TNT is a discussion about power, not energy per se. This is the same confusion that people have with regard to rocketry. They often talk about how much “energy” it takes to get into orbit, when in fact it’s not much more energy than it takes for intercontinental aircraft flight. The difference is that the airplane deploys its energy over many hours, whereas the rocket must do so in a very few minutes. When the Shuttle took off, it generated more power than the entire nation’s electrical grid for the first two minutes. In fact, when I was working propulsion at Rotary Rocket in the nineties, we used to joke about what units we should use to describe the power output of the engine, and thought that “Hoovers” (as in the dam) would be a useful one.

In any event, radiation and heat or no, either exploding meteoroids or nuclear weapons city busters, and events to be concerned about.

Mathematics, Media Criticism, Political Commentary, Science And Society, Space, Technology and Society

Chelyabinsk: What Just Happened?

2 Comments

My thoughts over at PJMedia.

[Update a few minutes later]

Deep Space Industries has already jumped on the PR opportunity:

McLEAN, VA – February 15 – Today’s impact in Russia and the near miss by
asteroid 2012 DA14 should shock the world into creating a sentry line of
spacecraft circling the Earth to intercept and evaluate incoming threats, Deep
Space Industries proposed.

“The hundreds of people injured in northern Russia show it’s time to take action
and no longer be passive about these threats,” said Rick Tumlinson, chairman of
Deep Space Industries.

Deep Space Industries proposes establishing several sentry lines encircling
Earth with small spacecraft able to dart after intruders to get close-in photos
and data as they pass. Over time additional spacecraft able to grab samples for
analysis on Earth would join the sentry lines.

Not all asteroids are the same, and to be ready to deflect one that’s on a
dangerous trajectory the world needs to know more about their structure and
composition. Many may be solid but all photos so far have shown gravel and rock
piles. A defense plan assuming the wrong type could make matters worse.

“Placing ten of our small FireFly spacecraft into position to intercept close
encounters would take four years and less than $100 million,” said David Gump,
CEO of Deep Space Industries. “This will help the world develop the
understanding needed to block later threats.”

There are estimated to be more than 10,000 near Earth asteroids that could
destroy a major city and a hundred that would end civilization. Near Earth
asteroids are confirmed at a rate of more than 900 per year, but as yet little
is known about their composition and structure.

“Observations by space telescopes like the Sentinel planned by the B612
Foundation and the smaller units offered by Planetary Resources should be
supported,” Tumlinson said. “Astronomical observations are a good first step but
at Deep Space we believe we need get up close and personal. Then when these
objects are identified, we can launch one or more FireFlies to intercept them,
and give us close-up images so that we understand what we are dealing with.”

Deep Space Industries is preparing the FireFly series to begin prospecting in
2015 for asteroids that are very small, five to seven meters in diameter. The
same FireFly prospecting design would be used in the sentry line of asteroid
interceptors.

Then in 2020, Deep Space will bring one of these tiny rocks back to a parking
orbit near Earth to be harvested for its water, rocket fuel, and metals for
in-space customers such as communications satellites that have run out of gas.
The larger harvesting spacecraft might be the basis for interceptors that could
nudge larger threats into trajectories that miss Earth.

In the coming months Deep Space Industries will be offering plans to develop a
coordinated low-cost commercial solution to setting up humanity’s first line of
defense against asteroid threats.

“While our primary mission is the harvesting of asteroid resources, we believe
that virtually the same effort and technology can be applied to removing this
threat to our precious planet,” Tumlinson said.

I suspect Planetary Resources won’t be far behind.