Tag Archives: Ralph McNutt

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NASA and Nuclear Power

marssoilviewNASA’s history with nuclear power dates all the way back to the early 1960s when the U.S. Navy launched a navigation satellite powered by nuclear energy.

Nuclear energy’s ability to withstand the most extreme conditions has made it an important part of space missions, including the Mars 2020 mission. The next journey to the Red Planet will focus on bringing back soil samples and exploring the atmosphere of Mars to determine its habitability for human life.

NASA recently highlighted the significance of nuclear energy stating, “Mars, Venus, Jupiter, Europa, Saturn, Titan, Uranus, Neptune, the moon, asteroids and comets.  A number of these missions could be enabled or significantly enhanced by the use of radioisotope power systems (RPS).”

A RPS works like this: Through the natural decaying process, isotopes produce a tremendous amount of heat. In the case of an RPS, as the isotope plutonium-238 decomposes the heat is converted into electricity which in turn is used to power travel through space. Plutonium-238 is an artificial element with a half-life of 88 years. The longevity of nuclear energy makes the RPS an ideal and reliable source of power generation even under the harshest of circumstances.

The challenging environment includes temperature extremes not known to earth. Take the moon for example. Temperatures on the surface of the moon can fluctuate between highs of 125 degrees Celsius and lows of -175 degrees. Another challenge with travelling to the outer reaches of the solar system, such as with the New Horizons missions, is being able to conduct research in the dark, requiring a power source that can still operate without the energy of the sun.

For the Mars missions, a big factor in power selection is dust. During its infamous dust storms, the red planet can kick up dust to last for weeks at a time, coating “continent-sized areas,” according to NASA.

Nuclear power has the added benefit of being compact.

“Solar would be too big and we’ve that learned dust in the Martian atmosphere accumulates on the solar cells, so unless you have wind storms to clear them off, you will kill the missions off by running down the batteries,” according to Dr. Ralph McNutt, principal investigator for the New Horizons Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI), from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “If you want to run rovers on Mars and do it accurately and if you want to go to the moon and really investigate in permanent shadows you need nuclear power.”

Compact size isn’t just beneficial, it’s required when working in outer space. Einstein’s theory of relativity (E=Mc2), essentially states that the further the distance you want to travel, the more speed is required, therefore the mass of the object travelling must decrease.

The Rover for Mars 2020 will be about the size of a car and will measure approximately 7 feet in height. The nuclear powered MARS 2020 mission will launch in the summer of 2020 and could provide new clues to past life on the not so distant planet.

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Powering Pluto

Image Credit: NASA, Johns Hopkins University Applied Physics Laboratory, Southwest Research Institute
Image Credit: NASA, Johns Hopkins University Applied Physics Laboratory, Southwest Research Institute

Nuclear technology is helping to make history on the solar system’s icy planet.

A “Pluto Not Yet Explored” stamp has pasted itself into history books after travelling more than 3.2 billion miles, over 5 billion kilometers, to Pluto and beyond.

The mission has landed NASA a spot in the Guinness World Record Books.

The accomplishment is no small feat. NASA’s New Horizons spacecraft was first launched just over 10 years ago, in early 2006, to study Pluto and the Kuiper Belt close-up. Cold, dark and almost 4 billion miles away from the sun meant that solar power, batteries and fuel cells weren’t viable options to power the mission.

In order to reach the outer icy reaches of our solar system, NASA needed help from an energy source that could survive the most extreme conditions.

So for Pluto, NASA went nuclear.

“We needed a reliable source of power and we’ve put a great deal of money and research into them (the power supplies) so that was really the way to do the mission and  have the highest reliability to run the space craft,” states Dr. Ralph McNutt, principal investigator for the New Horizons Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI), from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

It’s called a radioisotope thermoelectric generator or RTG for short. Think of it as a “nuclear battery” to power spacecraft. RTGs are powered by an isotope known as plutonium-238, an artificial element which has a half-life of almost a century. As this isotope decays it produces heat which is converted into electricity. The electricity required to power the Pluto mission is about 200 watts, the same as using two one-hundred watt light bulbs.

In deep outer space exploration mere seconds can make all the difference.

“Pluto takes approximately 250 years to get around the sun so you have to really know where Pluto is,” according to McNutt.  “We were off by 85 seconds at closest approach [in July 2015], which was really good, but you have to realize we were travelling at 14 kilometers per second. Times that by about 100 seconds and that’s almost 1,400 kilometers, a little bit more than the radius of Pluto.”

In order not to miss out on the opportunity to capture a picture of the dwarf planet, the team of scientists instructed the camera to take pictures of a larger amount of outer space, so that they wouldn’t miss Pluto or its moons as the spacecraft flew by.

Since the miniature planets discovery almost 100 years ago, in 1930, little was known about Pluto. In 2015, images of the planet sent back by New Horizons raised new questions about our solar system. The images sent back reveal glacier-like activity, among many other features, providing new information on the history of our solar system.

The Guinness World Record – awarded for longest distance traveled  for a  postage stamp that engineers affixed to the spacecraft shortly before launch – came around the same time that NASA celebrated 40 years of robots on Mars. Soon, NASA will launch Mars2020 as a first step to hopefully bring back to earth a sample of soil from the Red Plant; a potential space accomplishment made possible thanks to nuclear power.