Plutonium Batteries

By | July 23, 2009

Do the Mars rovers have plutonium batteries?

In fact, the Spirit and Opportunity rovers can stay warm and keep collecting data for nearly five times longer, thanks to about an ounce and a half of Los Alamos plutonium-238. Los Alamos’ Pu-238 Science and Engineering (NMT-9) Group made eight lightweight radioisotope heater units each for the Spirit and Opportunity rovers. Each of the 16 units contains just under one-tenth of an ounce of plutonium, and each pumps out a continuous one watt of heat as the plutonium decays. Housed inside the rover fuselages, called Warm Electronic boxes because they provide a temperature-controlled environment, the heater units keep electronic and mechanical components warm enough to function reliably in the bitter cold of space. They transfer heat directly to the rover systems and instruments, without moving parts or electronic components. The heater units are the latest in a long line of plutonium heaters and thermal batteries fabricated at Los Alamos for all of NASA’s deep space probes, as well as for the Sojourner rover, which explored the red planet for three months as part of NASA’s Pathfinder mission in the summer of 1997. The heat comes from plutonium-238, the shorter-lived and much hotter cousin of weapons-grade plutonium, or plutonium-239. –

NASA does have plans to use plutonium batteries on Mars:

… Nuclear powered, the big-car sized vehicle won’t suffer the serious constraints imposed by using solar power on Mars, further from the Sun than Earth. It will be able to tool about drilling into rocks (or “vapourising” them with its laser) for a full Martian year (nearly two Earth ones) before its plutonium battery pack runs out of puff. The MSL is a way over budget, seemingly, with $1.5bn already spent. There has been talk recently of cancelling it. However, it now seems clear that the programme will proceed. There’s more on MSL from NASA herethe register

The earliest working plutonium battery I’ve found a photo of so far is from 1973.  The first public reference I found was June 2, 1967 New York Times:

Jun 2, 1967 – They can operate in shadow or far out away from the sun where the cold of space would freeze ordinary batteries. They are considered particularly important for future military and civilian space missions that will require large amounts of power. i The first Navy units used plutonium

Going back farther, we know plutonium batteries were operating in space on October 24, 1961 based on this paper where Dr. Glenn T. Seaborg, Chairman of the US Atomic Energy Commission says at an International Symposium on Aerospace Nuclear Propulsion conference in Las Vegas:


How do Plutonium batteries work?

Space batteries work by converting heat from the radioactive decay of plutonium-238 — the sister to plutonium-239 used in nuclear weapons — into electricity. The batteries are considered the best power source for unmanned space vehicles, producing hundreds of watts of electricity for decades. The plutonium batteries aboard the Voyager 1 spacecraft, launched in 1977, were still working at 80 percent capacity when it left the solar system in 2003. – globalsec

Plutonium 238 is used in radioisotope thermoelectric generators, which convert the heat of radioactive decay into electricity to power long-distance spacecraft. The Cassini spacecraft… has three generators.

Neat stuff, right? Problem is, even a tiny speck of it can kill you.

plutoniumAll Things Considered, August 4, 2005 · Fifteen years ago, the United States stopped making plutonium-238, one of the most toxic substances known to man. It can be fa tal to inhale so much as a speck of the radioactive isotope. But now, citing national security needs, the government is preparing to start making it again at a federally owned site in the Idaho desert. Plutonium-238 is far more radioactive than its cousin, plutonium-239, which is used in bombs. It’s so radioactive, it stays hot to the touch for decades. It is useless for commercial nuclear power plants, but ideal to make small, long-lasting batteries for devices such as space probes and espionage equipment. –

This is an image of a glowing red hot pellet of plutonium-238 dioxide to be used in a radioisotope thermoelectric generator for either the Cassini mission to Saturn or the Galileo mission to Jupiter. This image was provided by the Department of Energy via email and was taken at the Department’s Los Alamos National Laboratory. Each pellet produces 62 watts of heat and when thermally isolated, can glow brilliant orange.. Excerpt from email: “The pellet is glowing red because of the heat generated by the radioactive decay (primarily alpha) of the fuel. [Photos of glowing pellets are typically taken after insulating the pellet under a graphite blanket for a period of time (minutes), removing the blanket, and taking the picture.] These pellets were used in the RTGs that powered NASA’s Galilleo and Cassini spacecraft on missions to Jupiter and Saturn, respectively. The pictures now being sent back from Saturn by the Cassini orbiter are made possible through this unique fuel source. – wiki

Could a pound of it kill everyone on earth? Not really.

In regard to the statement that 1 pound of Pu would kill everyone on Earth… One pound of plutonium would be enough to give 1.6E+9 persons a CDE of 50 rem (0.5 Sv) {which could result in 1.5E+5 additional cancers} *IF* and ONLY IF the material was pulverized into particles of respirable size and the material could be adequately dispersed in the atmosphere. A few decades ago the United States and other countries engaged in atmospheric nuclear bomb testing. These tests released many pounds of radioactive isotopes, including plutonium, to the atmosphere. Although there is some evidence of increased incidence of cancer among “downwinders”, there have not been 1.5E+5 cancers in excess of the number expected. So it would be practically impossible to kill everyone on earth with one pound of plutonium. –

For now, plutonium batteries are still far too dangerous to use on earth. We did not always know this, it seems.  For example, there were once plutonium powered pacemakers. Theodore W. Gray. writes that he received the following information from Andrew Hansen:

PacemakerPlutonium PacemakerThe R9000 was circa about 1970 and was, by today’s standards, quite simplistic. It sold mostly behind the old iron curtain and some devices are still going but not many. The idea did not take off in the west for two reasons. The first is the hysteria of implanting plutonium. The second is that most pacemaker companies (and there are only 4 that sell world wide-the list goes up to about 6-8 if you include companies that sell in Europe only) and each company will bring out a new model every 1 to 2 years. Today’s devices use either lithium iodine or lithium monofluride batteries and last around 8 years. That means that by the time your battery runs out your device has been superseded at least 3 times.

When the patient finally dies the mortician may look for and explant a pacemaker – they’re easy to see as they are implanted between the skin and the muscle in the upper chest just under one of the collar bones – but if the family plan to bury rather than cremate then the mortician may not bother.

Pacemakers must be explanted for cremation as a lithium iodine cell has a lot of really powerful chemistry in it – usually 1.2Ahr with a rundown curve that stays flat at the nominal voltage for 90% of its working life before a rapid rundown. If you incinerate one of those little beauties they will actually damage the furnace (which happened here in Oz some years back).

So you can see that it all hinges on the mortician and companies and other health care workers generally have very little contact with them so they have no idea what to do or what to look for.

Here is part of a letter in which the NRC fines a hospital regarding plutonium powered pacemakers:

In 1978, a patient was implanted with a nuclear pacemaker by staff at Lower Bucks Hospital (LBH) as authorized by LBH’s NRC license. The pacemaker was explanted at Nazareth Hospital on October 31, 1996, after the patient had expired. Although you were notified on November 2 or 3, 1996, that the patient had expired and that the pacemaker had been explanted, you did not contact the NRC within 24 hours, which constitutes one of the three violations. Also, on December 10, 1996, you were notified by a representative of Nazareth Hospital that the pacemaker could not be located and was assumed lost. Although you had contacted the supplier of the pacemaker to retrieve the pacemaker and properly dispose of it, you did not communicate effectively with Nazareth Hospital, to ensure appropriate control and disposal of the pacemaker. These failures resulted in two additional violations of NRC requirements.

Furthermore, during the inspection, the NRC learned of two additional instances (January 5, 1981 and September 18, 1983), in which pacemakers were buried with patients, and one additional instance in which the pacemaker was not returned to the supplier (August 1987). All three of these occurrences are similar to an occurrence at your facility in 1987 in which two pacemakers were buried with patients after the patients had expired. As the hospital that had initially implanted the pacemakers, as authorized by your NRC License No. SNM-1800, you were responsible for taking appropriate and timely action to ensure proper retrieval and disposal of pacemakers. This did not occur. Given the significance of improper disposal of this material, the violations have been classified in the aggregate as a Severity Level III problem in accordance with the “General Statement of Policy and Procedure for NRC Enforcement Actions” (Enforcement Policy), NUREG-1600. –

Other sources besides plutionium have been used for pacemakers. Click here for THE article on nuclear pacemaker batteries [.pdf]


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