NASA’s Plutonium Tours U.S. Before Heading To Mars

The plutonium-238 that powers NASA’s rovers on Mars crisscrosses the United States first on a tour of national laboratories.

Department of Energy officials outlined the path and process of manufacturing the Pu-238 for the Perseverance Rover that launched in July and is already about two-thirds of the way to the Red Planet.

“Perseverance’s nuclear heart completed its own journey of seven years and nearly 5,000 miles before finally meeting up with the rover at Kennedy Space Center in Florida,” said Matt Dozier, the host of DOE’s Direct Current podcast.

NASA uses a solid-state nuclear battery, called a Multi-Mission Radioisotope Thermoelectric Generator, instead of, say, solar arrays, so the rover can keep operating during dust storms and the Martian night. With a halflife of 90 years, Pu-238 can keep a craft powered for decades.

“What’s the secret to their longevity?” Dozier asks. “It’s not turmeric, or acai berries, or wheat germ—the Mars rovers, and dozens of other NASA missions, run on a diet of pure plutonium-238.”

The $75 million MMRTG produces about 110 watts of electricity from the heat of decaying PU-238.

Dozier interviewed DOE officials tasked with processing and securing the dangerous isotope during each step of its manufacture:

1 Idaho National Laboratory: The fuel begins its journey as neptunium-237, a by-product of nuclear reactors that’s stored at Idaho National Laboratories. “The Oak Ridge National Lab essentially calls up the Idaho National Lab and phones in a shipment, let’s say, for neptunium,” said Robert Wham, program manager for the Pu-238 Supply Program at Oak Ridge. “We get neptunium on a just-in-time basis; it’s shipped to us, and then we do the chemical processing here.”

2 Oak Ridge National Laboratory: Oak Ridge mixes the Np-237 with aluminum and bombards it with radiation in a reactor for 50 to 60 days. Some of the Np-237 turns into Pu-238, which Oak Ridge technicians separate, collecting plutonium as a powder. Oak Ridge also builds an iridium cladding that should keep the plutonium contained.

“One of the things that we worry about is that if there’s an accident either during launch or shortly after launch, that when these generators come back to Earth, and they’ll crash into Earth at very high velocities, very high speeds,” said Easo George, an alloys expert who serves as the governor’s chair at the Department of Energy’s Oak Ridge National Laboratory and the University of Tennessee. “And we want to make sure that if—such a very low-probability event—but if something like that were to happen, that the iridium would contain the plutonium fuel and prevent it contaminating areas around where it strikes.”

3 Los Alamos National Laboratory: The Pu-238 then heads 1,400 miles west to Los Alamos

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College Football Playoff Picture for Week 10: Four in, four out heading into November

The College Football Playoff puzzle is more difficult than ever to piece together in a season impacted by the COVID-19 pandemic.

That said, the season enters November with the Pac-12 and Mid-American Conference returning to action and several teams finding separation. Everyone is playing, and while the race might be in different stages across the FBS, the chase is on.

The first set of CFP rankings won’t be revealed until Nov. 24, so there are three more weeks of game action.

Ranking announcement Date
First Tuesday, Nov. 24
Second Tuesday, Dec. 1
Third Tuesday, Dec. 8
Fourth Tuesday, Dec. 15
Final Sunday, Dec. 20

With that in mind, Sporting News breaks down the College Football Playoff picture with four teams in, four teams out and four teams to watch heading into the first week of November:

Four In

1. Clemson (7-0)

Backup quarterback D.J. Uiagalelei and star rusher Travis Etienne led Clemson to a 15-point halftime comeback in a 34-28 victory against Boston College. Trevor Lawrence won’t play next week against Notre Dame while recovering from COVID-19. If the Tigers win anyway, they can take complete control of the ACC race. It’s on the defense to put four quality quarters together this time.

MORE: Big questions for Clemson-Notre Dame

2. Ohio State (2-0)

The Buckeyes jumped out to a big halftime lead and cruised to a 38-25 victory at Penn State. Justin Fields, who hit 28 of 34 passes for 318 yards and four touchdowns, has emerged as a Heisman Trophy favorite. There is no end in sight to Ohio State’s Big Ten dominance under second-year coach Ryan Day. Ohio State resumes action against Rutgers in prime time next week. Former Buckeyes defensive coordinator Greg Schiano will be on the other side.

3. Alabama (6-0)

Is Mac Jones or Najee Harris the better Heisman Trophy contender? That’s an open-ended question that can be discussed over the bye week. The Crimson Tide remain the team to beat in the SEC after a 41-0 shutout win over Mississippi State’s Air Raid offense. The remaining schedule features LSU, Kentucky, Auburn and Arkansas. It’s possible that none of those teams will be ranked when they play Alabama. The path toward yet another SEC championship appearance is open for Nick Saban, who celebrated his 69th birthday in style.

4. Notre Dame (6-0)

The Irish improved to 6-0 with a 31-13 victory against Georgia Tech, and that sets up a top-five showdown with Clemson at Notre Dame Stadium next week. Ian Book has lost just three games as a starter with the Irish, but two of those were against top-10 teams. Notre Dame can take a big step toward a second Playoff berth under Brian Kelly with a victory against the Tigers. The Irish are 2-5 at home against the No. 1 team, and the “Bush Push” game in 2005 was the last one.

MORE: Michigan, Jim Harbaugh get that sinking feeling again in stunning loss to Spartans

Four out

5. Georgia (4-1)

Georgia returned from

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