Some leftist activists are strongly against using nuclear power sources on space missions, currently New Horizons, due to the chance of them blowing up and scattering the material in our atmosphere, hurting civilians, and the environment.
Twenty-four pounds of radioactive plutonium is located in New Horizon's [sic] radioisotope thermoelectric generator, an aluminum-encased, 123-pound cylinder, 31/2 feet long and 11/2-foot wide, that sticks out of the spacecraft like a gun on a tank.
Inside the cylinder are 18 graphite-enclosed compartments, each holding 1 1/3 pounds of the plutonium dioxide. Similar generators previously have been used to power six Apollo flights and 19 other U.S. space missions.
NASA and the U.S. Department of Energy have put the probability of an early-launch accident that would cause plutonium to be released at 1 in 350 chances.
NASA last year estimated the cost of decontamination, should there be a serious accident with plutonium released during the launch, at anywhere from $241 million to $1.3 billion per square mile, depending on the size of the area.
If there was an accident during an early phase of the launch, the maximum mean radiation dose received by an individual within 62 miles of the launch site would be about 80 percent of the amount each U.S. resident receives annually from natural background radiation, according to NASA's environmental impact statement.
On the one hand, that 1/350 is a scarily high chance of failure resulting in the scattering of radioactive material. On the other hand, if it happened it wouldn't be that big a deal because the launch location is remote, and the dosage is small.
Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body.
(DOE Office of Civilian Radioactive Waste Management)
The DOE says that US citizens absorb 360 mREM a year, of which 55 mREM are from natural background sources. According to Wikipedia, at less than 50 REM, there are no noticeable symptoms. That was 50 REM. Combining the data from the DOE and NASA's prediction of how much radiation would be produced, if the New Horizons mission exploded, you would receive roughly some 50 mREM or 0.05 REM. Even if we instead used the 360 mREM figure, that'd still amount to getting less than 0.36 REM if New Horizons blew up on your doorstep. Folks, the plutonium reactor "battery" just isn't a big deal.
As for why we *need* the nuclear power in the first place, Wikipedia (again) has an article on the Galileo mission that also faced the same issue with power. That far from the sun, that long a mission, there *are* no other options. Conventional batteries won't last long enough (either due to the amount of energy required, or due to the conditions of space), combustion isn't efficient enough (it'd take too much to launch that amount of fuel into space), and if we wanted to use solar energy we'd need more than 700 square feet of solar panels. That far out, it's kinda hard to tell the Sun from any other star, and I've never heard anyone trying to run the electrical needs of a car on starlight alone. Sorry fellow liberal folks, nuclear's our only choice.
But it's not a big deal, so stop flipping out! Jeez.