8 months ago

UAH modeling the spacecraft for NASA’s nuclear thermal propulsion idea

Successful human spaceflight to Mars and back is bound by basic rules of physics that any home garage hot rodder knows: mass, power and fuel consumption. To complete the mission, there must be enough thrust to propel a spacecraft’s weight to the target destination and enough fuel economy to ensure there is adequate propellant.

Nuclear thermal propulsion (NTP) can help achieve the goals of low weight, high power and good economy. An NTP engine uses low enriched uranium (LEU) to heat a lightweight propellant such as liquefied hydrogen to 2,800 degrees Kelvin through channels in the core.

The expanding gas exits the nozzle, providing thrust. If something goes awry and the craft crashes to Earth, the engine design and use of LEU reduce the chance of a catastrophic nuclear incident to near zero, as well as making flight safer for the crew.

NASA studied nuclear propulsion early on with the roughly two-decade-long Nuclear Engine for Rocket Vehicle Application (NERVA) program that ended in 1972. Current NTP research can be viewed as a modern-day progeny of NERVA.

“The heartbeat of the program at this time is demonstrating that the reactor elements can be manufactured such that they will function in and survive the intense environment internal to the engine,” says Dr. Dale Thomas, UAH’s eminent scholar in systems engineering, who is the principal investigator for a UAH research grant with NASA’s NTP Program Office.

Under the management of NASA researcher Dr. Bill Emrich, who teaches nuclear propulsion as an adjunct UAH faculty member, that testing is underway at NASA’s Marshall Space Flight Center (MSFC) in the Nuclear Thermal Rocket Element Environmental Simulator (NTREES) facility.

As all hot rodders know, swapping engines can pose technical challenges. That’s why NASA has a research grant with The University of Alabama in Huntsville (UAH) to model how a spacecraft might be engineered to work with NTP, en route to an eventual test flight. NASA is currently focused on determining the feasibility and affordability of an LEU-based NTP engine with solid cost and schedule confidence. The space agency has started looking into a potential flight demonstration as a follow-on project in the mid-2020s.

UAH’s Propulsion Research Center (PRC) manages the university’s role in the project. The university’s Complex Systems Integration Laboratory in its Rotorcraft Systems Engineering and Simulation Center (RSESC) is working closely with MSFC and private contractors to solve the challenges and exploit the opportunities created by a nuclear reactor at the heart of a rocket engine.

“We’re trying to figure out – assuming you can make the engine – can we fit it to the vehicle and make it work,” says Dr. Thomas, who incidentally is swapping engines to hot rod a classic pickup truck at home.

UAH’s research focus is not on the reactor design, but rather on modeling the spacecraft during a human mission to Mars.

“How does the utilization of NTP affect the mission architecture and the spacecraft design and operation within that mission architecture?” Dr. Thomas asks. “What all do we have to change in what we’re used to doing in designing a human crewed spacecraft?”

NTP is such a radical departure from liquid fuel rockets that even the NASA phrase “We have ignition” becomes obsolete because the propellant isn’t burning. The crew will be shielded from the LEU in the reactors and will “get more radiation from deep space than from this engine,” Dr. Thomas says. Yet the reactor poses other design challenges.

One of the first problems that NASA asked UAH to research is the heating effect that the NTP engine’s gamma ray and neutron emissions will have on the hydrogen stored in the propellant tanks.

“Hydrogen, which must be in its liquid state to be used as NTP propellant, must be chilled to near absolute zero,” Dr. Thomas says. “And it turns out that hydrogen is a great absorber of neutrons and a good absorber of gamma rays.”

As the hydrogen absorbs the particles, heat is generated.

A team led by Dr. Jason Cassibry, associate professor of mechanical and aerospace engineering, is modeling the behavior of the hydrogen in the system with the goal of keeping it liquid until the precise time it is to be expended.

“Storing hydrogen on a mission for months at a time is difficult, and every little thing that heats up the hydrogen is a problem,” says Dr. Cassibry.

His computer modeling explores the impacts of variables such as the craft’s trajectory and the design of the hydrogen tanks.

“Downstream of the reactor, we’re modeling the flows of hydrogen and using those to validate the data against the results from the NERVA rocket development in the ’60s and ’70s,” Dr. Cassibry says. “We’re looking at the fuel economy and the thrust that comes out of the cone.”

The initial modeling is being done at full power, but Dr. Cassibry expects that in a year or two, the team will begin to model the throttling process.

The stack of an NTP rocket begins with the nozzle, where liquefied hydrogen undergoes rapid expansion. Next up is the nuclear reactor, supplying heat to the nozzle. The reactor will only be powered up once conventional rockets have lofted parts of the craft into space so it can be assembled there. While on Earth, the reactor is in safe mode. Atop the reactor is the hydrogen storage, and atop that is the crew module.

Very cold and very light, liquid hydrogen is also a viscous fuel that can be hard to pump and utilize. UAH is investigating whether injection seeding the hydrogen with a noble gas such as argon would make it flow better. However, the argon seeding will affect engine performance.

“In rocket terms, you talk about specific impulse. How much energy can you get out of a fuel?” Dr. Thomas says. “When an engine is running hydrogen, it has one thrust level. If you seed it with argon, it generates more thrust, but at less efficiency.”

The researchers are investigating whether seeding improves thrust enough make up for the loss of efficiency, while at the same time conferring the benefit of better fuel flow.

NTP engines generate high thrust at over twice the specific impulse of the best chemical combustion engines. They also provide engineers with new opportunities for innovation.

“That’s why NASA brought us on board, to explore opportunities and to kind of look off into the distance to see what might be accomplished,” says Dr. Thomas.

One possibility that would appeal to a hot rodder: Add a conventional combustion component to the nuclear engine. Adding an oxygen tank to create an afterburner that ignites the hydrogen coming out of the nozzle could significantly boost thrust when needed.

Another intriguing opportunity lies in the reactor’s waste heat.

“When you look at it, a Mars spacecraft is going to require a big solar array to get its power, and that creates design challenges of its own in weight and strength,” Dr. Thomas says. “Plus, the farther away you get from the sun, the less efficient those arrays are going to be.”

Because it’s difficult to turn the reactor off and on due to the thermal effect on its materials, it has to idle when not in use. While idling, the reactor continues to generate heat. Perhaps hydrogen can be directed through the core to carry that heat to radiators coated with a thermoelectric compound that generates electricity, Dr. Thomas suggests. Or the heat could be used to run a mechanical generator.

“If we tap the power off the reactor, we may be able to do away with the array,” he says.

Exploring these kinds of design challenges and opportunities attracts graduate students to UAH from universities across the country, according to Dr. Thomas.

“It’s amazing, the team we have been able to build,” he says.

Besides Dr. Thomas and Dr. Cassibry, the NASA grant currently supports four graduate research assistants (GRAs). They are doctoral candidates Alex Aueron and Samantha Rawlins, and masters student Dennis Nikitaev. The team added another GRA position this fall and Dr. Thomas anticipates UAH’s role will expand in the future.

“My attraction to NTP research stems from the understanding that, from a technical standpoint, nuclear thermal propulsion is hands-down the best way to get humans to Mars in my lifetime,” Rawlins says. Because of their orbits, the energy required to travel from Earth to Mars reaches minimum expenditure every 16 years. The next opportunity is in 2033.

“We got to the moon in 8 years, so this is definitely possible, but it’ll require making sure we play our cards right,” Rawlins says.

“That’s what’s so exciting about working with Dr. Thomas on my research within the Complex Systems Integration Laboratory,” she says. “We’re using systems engineering to look ahead, question our current process and identify potential solutions or alternatives before they even become an issue.”

It’s the UAH team’s job to smooth the path for NASA to help it get to Mars, Rawlins says.

“With this research, it feels great to contribute to the next ‘giant leap for mankind,’ sending humans to Mars,” says Nikitaev. “The most challenging task is figuring out how to make all the components work together in a high fidelity NTP engine simulation.”

Being able to intellectually dream about possibilities “is one of the very best things I like about being at UAH,” says Dr. Thomas, who joined the university in 2015 after being associate center director (technical) at MSFC.

“What we’re doing here has wider implications for other areas,” he says. “NTP moves the ball on Dr. Cassibry’s work on PuFF (the Pulsed Fission-Fusion engine). It could even lead to a single stage to orbit engine.”

A hybrid NTP single stage to orbit engine could lead to the resurrection of a program similar to Lockheed Martin’s X-33, a NASA Reusable Launch Vehicle (RLV) testbed that was scheduled to fly 15 suborbital test hops before it was canceled in 2001.

“There’s potential to come up with an air-breathing engine in the thick atmosphere,” Dr. Thomas says, “and then use nuclear power once we get out of the atmosphere.”

(Courtesy the University of Alabama Huntsville)

5 mins ago

North Zone dove season opens on Labor Day weekend

Alabama Wildlife and Freshwater Fisheries (WFF) Director Chuck Sykes wants to make sure dove hunters are not caught flat-footed this September when the season opens earlier than usual.

The North Zone dove season will open on Labor Day weekend this year, a week earlier than most people are accustomed to. Sykes wants to get the word out well ahead of the season.

“Most people, me included, typically think dove season opens in the North Zone the first Saturday after Labor Day,” Sykes said. “That’s the way it’s been most years. There have been a few times since 2000 that the season has come in the Saturday of Labor Day weekend.”

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Because of a variety of opinions about when Alabama’s dove seasons, North and South zones, should be set, WFF officials decided that a survey inviting public input would be the best way to accommodate the majority of dove hunters.

“With anything we do, you’ve got some people who want the season to start early,” Sykes said. “You’ve got some who want to start late. Some want to hunt in October. Everybody has their own idea about what they want dove season to be, or any season for that matter. What that survey showed was that the majority of people wanted it to come in as early as it could in September. They wanted as many weekends and holidays as possible included where they would have opportunities to go. With Labor Day falling later this year, we had to decide if we wanted to push the season to September 12 in the North Zone or if we wanted to have it Labor Day weekend. There’s pros and cons to both sides, but we looked at what that survey said. The majority said they wanted it early, so we gave them the earliest date possible. We were also giving them an extra weekend and giving them a holiday. Those were all three things that ranked extremely high on our survey.”

The North Zone 2020-2021 season is set to start on September 5 and run through October 25 for the first segment. Hunters on opening day can hunt from noon until sunset. After opening day, hunting is allowed from one-half hour before sunrise until sunset. The daily bag limit is 15 birds of either mourning doves or white-winged doves or a combination of the two. The second segment is November 21-29, and the final segment is set for December 12 through January 10, 2021.

In the South Zone of Baldwin, Barbour, Coffee, Covington, Dale, Escambia, Geneva, Henry, Houston and Mobile counties, the 2020-2021 season opens on September 12 and runs through November 1. The final two segments are the same as the North Zone.

“We know we can’t make everybody happy,” Sykes said. “This isn’t something we took lightly. This isn’t something we didn’t deliberate. And it definitely wasn’t something where we didn’t listen to the hunters’ opinions. Basically, this is what the majority of the people who took the survey said they wanted. My biggest concern is that I didn’t want people to be caught off-guard. I wanted them to have plenty of time to make their plans for Labor Day weekend or vacation.”

Sykes also pointed out that hunters don’t necessarily have to plan a hunt on opening day, but it is available if wanted. Some may choose to wait until the following weekend.

Sykes and WFF Migratory Bird Coordinator Seth Maddox said the window for planting crops like corn, grain sorghum or sunflowers for doves has passed, but there is a short window for browntop millet remaining.

“You might be able to get some browntop millet in the ground in the next couple of weeks, but the time for other crops has passed,” Maddox said. “If you don’t have anything planted, the best thing to do is to bush-hog or burn off a field and prepare it by disking so that you have a well-prepared seed bed, and then top-sow some winter wheat. You can begin that as early as August, and you are allowed to plant up to 200 pounds of wheat per acre on a well-prepared seed bed.”

Anyone with questions can visit the ACES (Alabama Cooperative Extension System) website at https://www.aces.edu/blog/topics/forestry-wildlife/mourning-dove-biology-management-in-alabama/ to learn more about allowed agricultural practices for dove hunting are listed.

“We see it every year,” Sykes said. “Yes, you can plant for erosion control. You can plant for winter grazing. There are agricultural practices that are legal, but simply going into a pasture and top-sowing wheat is not an accepted agricultural practice. Disking a field and spreading cracked corn is not an accepted agricultural practice. The ACES website explains in great detail what agricultural practices are allowed so that you will be legal and have a successful dove hunt.”

Landowners and dedicated dove hunters sometimes make the extra effort by adding fake power lines to attract the birds. Maddox recommends giving the birds as many places to roost and loaf as possible.

“Don’t cut down dead trees near a field,” Maddox said. “They like to have those loafing trees to sit in and check out the field before and after they eat. If you can provide a water source for them, that can make a big difference. And make sure your seedbed is disked well. Doves don’t have strong legs to scratch at the ground like turkeys do to uncover seeds. Doves are also attracted to freshly turned soil. It exposes seeds that didn’t sprout and bugs they eat as well. They pick up bits of grit for their crops to help grind the seeds. Doves are definitely attracted to a freshly plowed field.”

Dove hunting is one of the most popular outdoor activities in Alabama and the nation.

“Most people wouldn’t know that doves are the most hunted and harvested game in the United States,” Maddox said. “In our most recent survey, we had about 36,000 hunters with 200,000 days in the field and a harvest of more than 1 million birds. Most hunters don’t hunt but five or so days a year, so that’s a lot of birds harvested in the first couple of weeks of the season.”

Maddox said the annual harvest has no impact on the overall U.S. dove population of about 250 million birds.

“Doves nest seven or eight times a year here in Alabama,” he said. “They are a short-lived bird with a high rate of reproduction, so we’re not hurting the population at all. This renewable and sustainable resource continues to offer abundant opportunities to Alabama hunters.”

David Rainer is an award-winning writer who has covered Alabama’s great outdoors for 25 years. The former outdoors editor at the Mobile Press-Register, he writes for Outdoor Alabama, the website of the Alabama Department of Conservation and Natural Resources.

14 hours ago

Former Etowah Co. sheriff sues ALdotcom, law enforcement officers over damaging story

Former Etowah County Sheriff Todd Entrekin is suing for defamation the individuals involved in a 2018 news story in which a woman accused him of illegal activities, including statutory rape.

The defendants listed in the suit include current Etowah County Sheriff Jonathan Horton, Oneonta Police Chief Charles Clifton, the parent company of Alabama Media Group’s AL.com and reporter Connor Sheets.

Horton was Rainbow City’s police chief at the time the story was published. He later beat Entrekin in a Republican primary to become the county sheriff.

The news story at the center of the lawsuit was published in 2018 under the headline “Police investigating allegations Alabama’s ‘Beach House Sheriff’ had sex with underage girls.”

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Entrekin was given the moniker ‘Beach House Sheriff’ because of a widely shared report from earlier in 2018 that detailed how he used an old Alabama law to keep for himself hundreds of thousands of dollars meant for feeding the county’s prisoners; the beach house had a similar price tag to the amount of money he kept.

Entrekin’s lawyers argue in the suit that the publication of the article alleging rape was “reckless and malicious” and in their mind more due to a collective animus from the defendants than proper journalistic and policing practices.

The claims at the center of the 2018 article are made by a woman named Mary Elizabeth Cross, who alleged that Entrekin committed statutory rape by having sexual relations with her at drug-fueled parties in 1992 when he was 29 and she was 15. Cross was age 41 in 2018 when she came forward with the allegations.

Entrekin told AL.com at the time, “I’ve never had sex with any 15-year-old girl or had drugs around or anything. I have never done drugs in my life. That’s the most absurd thing I’ve ever heard of. Never, ever has anything like that happened before.”

Cross brought the accusations to Horton in 2018, who was police chief of Rainbow City at the time. Horton was also then running against Entrekin in a campaign to be Etowah County Sheriff, so he referred the case to Oneonta Police Chief Charles Clifton.

Entrekin’s lawyers argue in the suit that Oneonta Chief Clifton has been “harboring a personal grudge against” against Entrekin “since the 1990s” that stemmed from “past professional interactions.”

The AL.com report says Clifton is the individual who contacted reporter Connor Sheets about the allegation, and two reporters and law enforcement officers interviewed her together during a long drive.

The lawyers for the former sheriff make similar claims that both Sheets and Horton participated in the article out of personal dislike for Entrekin.

Horton’s dislike, they argue, stems from what was in 2018 his ongoing campaign against Entrekin for the county sheriff position.

Sheets, they allege, harbors “a demonstrated dislike for Alabama sheriffs generally, and Mr. Entrekin in particular.”

In addition to Sheets, the suit names Advance Local Media, which publishes AL.com, along with the cities of Oneonta and Rainbow City, which employed Clifton and Horton respectively at the time of the article’s publishing.

The AL.com report cited a friend of Cross’, who the reporter allowed to remain anonymous, as corroborating the existence of the parties where young girls were with older men around the time of the alleged criminal behavior.

Entrekin’s complaint says that he did not purchase the lakeside property until 1995, three years after the incidents are reported to have happened. Additionally, a boat structure cited in the allegation against Entrekin was not built until 2009, his lawsuit contends as evidence in his favor.

The attorney for Entrekin filed the lawsuit in Etowah County Circuit Court. It can be accessed here.

The defendants in the suit did not return calls for comment left by the Gadsden Times, the paper closest to the relevant officials.

Entrekin’s lawyers said in a statement that their client “seeks to correct the record and repair some of the damage these defendants have done to his reputation and employment possibilities.”

Henry Thornton is a staff writer for Yellowhammer News. You can contact him by email: henry@yellowhammernews.com or on Twitter @HenryThornton95

14 hours ago

Officials say Alabamians cannot be required to wear a mask in order to vote

Secretary of State John Merrill on Friday released guidance from his office and Attorney General Steve Marshall saying face masks cannot be a requirement in order to vote in Alabama’s July 14 primary runoff election.

A release from Merrill’s office outlined that the secretary of state has received numerous inquiries from county and city officials questioning the legal authority to require or not require voters to wear masks. Various localities in the state have enacted general mask ordinances recently.

In public response to those inquiries, Merrill confirmed that state law does not place limits on an individual’s right to vote, citing Article III, Section 177(a) of the Constitution of Alabama, which reinforces the inherent right of eligible citizens to vote.

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Additionally, Merrill’s office advised that a notice from the attorney general’s office dated June 30 declared, “Though the Attorney General strongly recommends that voters and poll workers follow CDC guidelines when in public places and behave in a manner that is respectful of poll workers and fellow voters, it is clear that state law does not allow for an individual’s qualification to vote to be contingent upon the wearing of a mask or face covering, respecting social distancing, using gloves, or having a temperature in a normal range.”

Merrill stressed the bottomline.

“While it can be ‘strongly recommended’ that an individual wear a mask, it cannot be required,” he stated. “In our state, we will continue to see that the right for every eligible Alabamian to vote is protected.”

You can view CDC guidance for voters and election polling places here.

Sean Ross is the editor of Yellowhammer News. You can follow him on Twitter @sean_yhn

15 hours ago

How to save the 2020 college football season

The sports media and the political media world are gathering to undo college football.

Why? I can’t even begin to understand it.

But with the Ivy League ending their fall sports and the Big 10 ending non-conference games, with other conferences to follow, it is becoming increasingly clear that the game we all love will be killed by the end of the month, if not sooner.

The ending of non-conference games makes absolutely no sense.

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Look at the University of Florida and their schedule: They have a game with the University of Kentucky at home and an away game at Florida State. Which game do you think will get played (if there is a season)?

Kentucky, because it is in the same conference.

But Lexington and Gainesville are 708 miles away, while Gainesville and Tallahassee are around 150 miles away from each other.

So logistically, having Kentucky come to Florida is a bigger “hassle” but that game might get played.

If you can rationalize this using science, medicine, politics, logic, common sense or wild guesses, let me know.

This ridiculous decision all but dooms a season because it is indefensible and silly.

So, how do we fix this?

Throw out the conferences for a season and replace them with 50 state divisions and reset the schedule completely.

If the distance is an issue, and that’s the best reason I can come up with to end non-conference games, this eliminates that.

This will force every state to play all games in their home state, with no exceptions. These are trying times after all.

Here is a potential Alabama schedule:

9/5 – Alabama A&M  at Alabama
9/12 – Faulkner at Alabama
9/19 – Alabama at Samford
9/26 – Alabama at Troy
10/3 – UAB Blazers at Alabama
10/10 – Birmingham-Southern Panthers at Alabama
10/17  – Alabama at West Alabama
10/24 – Alabama at Alabama State
11/7 – Jacksonville State at Alabama
11/14 – North Alabama at Alabama
11/21 – Alabama at South Alabama
11/28 – Auburn at Alabama

This will be good for these schools to play the powerhouse. Maybe fans eventually get to see these games in person; the schools could even get some of that sweet TV revenue.

The rankings can be done, the same with the coaches’ and media polls.

When this schedule is done, have your conference championships and College Football Playoff as normal.

Is this the perfect system? No.

This is going to require innovation and new ideas. If you want an actual college football season, this is the best bet.

Any conference that thinks it is going to continue on, as usual, is crazy. The sports media is set for self-destruction with their thirst to insert politics into America’s avenues for escape. Killing the college football season is their goal.

They will chip away at them until they relent.

Economies will be further destroyed, jobs will be lost (in their industry as well), and lives will be changed forever.

When college football is officially canceled, we will all know things have changed for good.

It will happen.

15 hours ago

Five Guys workers who refused to serve cops have been fired, suspended

The Five Guys employees who reportedly refused to serve members of the Daphne Police Department have been fired and suspended, according to a statement from the company.

Yellowhammer News detailed earlier this week a report first made by WKRG that three Daphne police officers were refused service at a Five Guys location.

The national headquarters of the restaurant released a statement saying, “The actions the Daphne, AL franchise have taken include termination and suspension of the employees involved. The store has temporarily closed for further education and customer service training with a representative from the Daphne Police Department and will reopen at 4PM today, July 10th.”

“The actions and sentiments of a few employees in Daphne, AL do not represent Five Guys or the local franchisee,” added the company on Twitter.

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The incident caused uproar on social media from citizens angry that members of a police department were being refused service based on the uniform they wore.

“The Daphne Police Department appreciates the outpouring of support from our community and from supporters of Law Enforcement across the country. We also want to thank Five Guys on a corporate and local level. We have been working through this situation and there has been total cooperation. The Daphne Police Department does not think that the actions of a few employees represents Five Guys as a whole,” the Daphne police told FOX10 on Thursday, while the investigation was still underway.

The department also dispelled rumors that the officers were not wearing masks, saying, “All three officers were wearing masks the entire time they were inside of the establishment. The events that occurred while the officers were in the restaurant were unfortunate.”

Five Guys added on Friday that the chain was committed to “fair, respectful, and equal treatment for all customers.”

Henry Thornton is a staff writer for Yellowhammer News. You can contact him by email: henry@yellowhammernews.com or on Twitter @HenryThornton95