Mushroom Clouds in Space?

By Christopher Moore

The launch of the New Horizons, a probe with Pluto as its destination, was delayed today due to high winds. According to MSNBC.com, this is no big deal since NASA has a months worth of launch window to get the craft space-bound.

NASA still has nearly a month’s worth of launch opportunities ahead. But if the probe can’t be launched by Feb. 14, the mission would have to be put off for a year — and New Horizons wouldn’t arrive at Pluto until 2019 at the earliest.

The delay is welcomed by anti-science protesters who’s “No Nukes in Space” placards have graced the entrance of the Cape Canaveral Air Force Station for days. The Global Network Against Weapons & Nuclear Power in Space has organized a rather small protest of the launch due to fears of some sort of nuclear catastophe. MSNBC.com reports:

Only 30 anti-nuclear protesters showed up recently to oppose a plutonium-fueled mission to Pluto. The most raucous it got was when protesters tied colorful origami birds to the fence of the Cape Canaveral Air Force Station.

“Folks tend to forget,” said protest organizer Maria Telesca of the Global Network Against Weapons & Nuclear Power in Space.

But Telesca and other protesters said the threat of a nuclear accident is no less real with the New Horizons mission to Pluto than it was with the launch of Cassini to Saturn in 1997.

Of course, that threat is near zero.

The space craft contains 24 lbs. of plutonium whose radiactive decay will produce electricity to opperate the probe’s instuments. Pluto’s distance from the Sun and the energy needs of the probe rule out solar power, and the distance and time involved make convetional chemical batteries unworkable. So nuclear is the way to go. But is it safe? Should we worry about mushroom clouds in space?

Here are the facts:

• New Horizons does not have a nuclear reactor strapped to its side.
• The amount of plutonium is nowhere near enough to reach critical mass, so no run-away nuclear reactions are even theoretically possible. (There goes your mushroom cloud)
• A mission failure after the probe leaves our atmosphere poses NO threat to man-kind.
• An early-launch accident (within our atmosphere) can happen but the chances are calculated at 1 in 350.
• Even in the worst case scenario, there is a near zero probability of any sort of damage to any person.

So there is the possibility of an early-launch accident. What is the worst case scenario? Within about 62 miles of the launch site, an individual would receive about 80% of the amount of radiation the average American receives each year due to background radiation. What does this mean?

The average person in the U.S. receives an annual dose from natural radioactive sources of approximately 100 to 400 millirems. In our worst case scenario an individual at “ground zero” would be exposed to an additional 320 millirems of radiation. That is 720 millirems or 0.720 rems of total radiation exposure for the year. Is that a lot?

The mildest exposure level to be classified as “radiation poisoning” is 5 rems. At this level of exposure there are no symptoms, but there is the potential for cancer, although this is disputed.

For NASA to expose a single person to mild radiation sickness they would have to launch New Horizons about 70 times and catastophically screw it up every time all within the same month. This would require 70 different probes and 70 different Saturn V rockets. They would have to launch more than 2 rockets a day at a cost of $1.4 billion a day. And every single rocket would have to explode on the launch pad or shortly after take-off.

I think that puts the probablity of nuclear winter at somewhere close to zero. Our concerned anti-scientists should worry more about the rocket hitting someone’s house. Or hitting a bird, the dead carcass of which lands on an innocent bystander, killing him.

I’m thinking of starting the Global Network Against Space Rockets Hitting Birds That Subsequently Fall and Kill Humans. It’s no more absurd than “Mushroom Clouds in Space.”