I quote from it :No
Prototype nuclear battery packs 10 times more power
Our next smartphone or electric vehicle might be powered by a nuclear battery instead of your usual lithium-ion cell thanks to a breakthrough made by Russian researchers. This piece describes the design of a nuclear battery generating power from the beta decay of nickel-63, a radioactive...www.eurekalert.org
Your article is from 2018 and the above section mentions Carbon-14 which is what the NDB battery I mentioned uses. Or will use when the prototypes are built.
My point was that this technology is old I know newer ones are far more efficient but that is beside the point.
It depends on the scale, mass, dimensions of the spacecraft and its distance from the sunThe Rocket Engine That Proves Solar Thermal Propulsion Isn't Just a Crazy Theory
Hello, interstellar travel.
BY TIM CHILDERS
NOV 23, 2020
AURORA4233
Engineers at the Johns Hopkins University Applied Physics Laboratory are prototyping a previously theoretical rocket design that could someday take spacecraft to interstellar space. Their plan? Use heat from the sun, rather than combustion, to power a rocket engine.
- Engineers are designing a rocket engine powered by the sun.
- The engine would use heated and pressurized hydrogen to achieve efficiencies three times greater than conventional rocket engines.
- The researchers proposed using the sun to slingshot an experimental spacecraft into interstellar space.
Unlike a traditional engine that's mounted on the rear end of a rocket, the experimental solar-powered engine takes the shape of a flat shield made from black carbon foam. The engine would double as a heat shield, protecting the probe from the sun’s powerful rays, while coils of tubing filled with hydrogen lying beneath the surface absorb heat from the sun.
The hydrogen expands, becomes pressurized, and then explodes out from a nozzle, generating thrust. The scientists call it solar thermal propulsion.
“From a physics standpoint, it’s hard for me to imagine anything that’s going to beat solar thermal propulsion in terms of efficiency,” Jason Benkoski, a materials scientist at the Applied Physics Laboratory (APL), told WIRED. “But can you keep it from exploding?”
Benkoski and his colleagues from APL and NASA recently shared their design online at the 3rd Annual Interstellar Probe Exploration Workshop. According to Benkoski’s calculations, a real-life version of the engine could be three times more efficient than the most advanced chemical combustion engines used in today’s rockets.
In 2019, NASA partnered with APL to kick off its Interstellar Probe study. The study will determine missions that could be launched next decade to study science outside our sun’s sphere of influence. Where the solar system ends and where interstellar space begins isn’t completely agreed upon, but one metric is the boundary where the sun’s magnetic fields and solar winds that make up the heliosphere can no longer be detected—what scientists call the heliopause.
APL is looking for a probe that can travel three times farther than the outermost reaches of the heliosphere in less than two decades time—a distance of 50 billion miles. To put that into perspective, let’s take a look at the current record holder of the farthest distance traveled.
In 2012, the Voyager 1 spacecraft became the first manmade object to leave the confines of our solar system. After lifting off from NASA’s Kennedy Space Center in 1977 aboard the Titan III rocket, the space probe embarked on a 2-year journey to Jupiter, where it was slingshotted by the gas giant’s massive gravity to continue its journey to Saturn, Uranus, and Neptune. (See the spacecraft’s full timeline here).
As of today, almost four decades since its launch, Voyager 1 is more than 14 billion miles from Earth and traveling at 38 thousand miles per hour (mph). The team at APL wants to shatter this record by accelerating its spacecraft to 200,000 mph and making the journey in half the time.
To pull it off, the spacecraft will have to accomplish another first: performing an Oberth maneuver a mere million miles from the fiery surface of the sun. Coined by one of the founders of modern rocketry, Hermann Oberth, the maneuver takes advantage of the gravitational pull of a celestial body by using a spacecraft’s engines to further accelerate its fall into a gravitational well, as seen here:
CREATIVE COMMONS
It’s a lot like running down a hill to gain momentum for the uphill. The steeper the hill, or the closer you get to a gravitational body like the sun, the easier it is to gain speed and maximize your energy. The problem? The sun is very, very hot.
In 2025, NASA’s Parker Solar Probe will perform its closest approach to the sun. It will come within 4 million miles of the sun’s surface, travel at speeds exceeding 400,000 mph, and experience temperatures as high as 2,500 degrees Fahrenheit. To fight off the giant nuclear furnace’s heat, NASA equipped its probe with a 4.5-inch-thick carbon-composite shield.
If APL plans to send its probe within a million miles of the sun, it will need to withstand temperatures around 4,500 degrees Fahrenheit for 2.5 hours as it performs its Oberth maneuver. That’s why NASA is finding new materials that could coat the spacecraft and reflect the sun’s heat. Additionally, the hydrogen flowing through the heat shield could act like a radiator, displacing the thermal energy as propellant.
“We want to make a spacecraft that will go faster, further, and get closer to the sun than anything has ever done before,” Benkoski told WIRED. “It’s like the hardest thing you could possibly do.”
Benksoski and his colleagues at APL plan to submit a report on findings from their experimental rocket design next year.
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Jamahir's comment : I have four thoughts :
1. This is such a simple system for in-space propulsion. Why didn't someone think of it before ?
2. How big will this shield / engine have to be if it has to propel a SpaceX Starship type craft.
3. Is it something to do with the physical and chemical properties of Hydrogen ( liquid ? ) that it will be used here instead of a Noble Gas like Xenon ( which is used in electric engines ) or Liquid Methane ( which SpaceX wants to use in the Starship ) ?
4. The spacecraft will still have to carry a conventional rocket engine to propel when the sun becomes hidden from the craft for a long time and when the sunlight is weak ( can a lens be used ? ) and when the craft has to land, say on Mars.
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@ps3linux @Hamartia Antidote @Fawadqasim1 @Itachi
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How to get people from Earth to Mars and safely back again
by Chris James | Lecturer UQ
Brisbane, Australia (The Conversation) Dec 23, 2020
There are many things humanity must overcome before any return journey to Mars is launched.
The two major players are NASA and SpaceX, which work together intimately on missions to the International Space Station but have competing ideas of what a crewed Mars mission would look like.
The biggest challenge (or constraint) is the mass of the payload (spacecraft, people, fuel, supplies etc) needed to make the journey.
We still talk about launching something into space being like launching its weight in gold.
The payload mass is usually just a small percentage of the total mass of the launch vehicle.
Size matters
For example, the Saturn V rocket that launched Apollo 11 to the Moon weighed 3,000 tonnes.
But it could launch only 140 tonnes (5% of its initial launch mass) to low Earth orbit, and 50 tonnes (less than 2% of its initial launch mass) to the Moon.
Mass constrains the size of a Mars spacecraft and what it can do in space. Every manoeuvre costs fuel to fire rocket motors, and this fuel must currently be carried into space on the spacecraft.
SpaceX's plan is for its crewed Starship vehicle to be refuelled in space by a separately launched fuel tanker. That means much more fuel can be carried into orbit than could be carried on a single launch.
Time matters
Another challenge, intimately connected with fuel, is time.
Missions that send spacecraft with no crew to the outer planets often travel complex trajectories around the Sun. They use what are called gravity assist manoeuvres to effectively slingshot around different planets to gain enough momentum to reach their target.
This saves a lot of fuel, but can result in missions that take years to reach their destinations. Clearly this is something humans would not want to do.
Both Earth and Mars have (almost) circular orbits and a manoeuvre known as the Hohmann transfer is the most fuel-efficient way to travel between two planets. Basically, without going into too much detail, this is where a spacecraft does a single burn into an elliptical transfer orbit from one planet to the other.
A Hohmann transfer between Earth and Mars takes around 259 days (between eight and nine months) and is only possible approximately every two years due to the different orbits around the Sun of Earth and Mars.
A spacecraft could reach Mars in a shorter time (SpaceX is claiming six months) but - you guessed it - it would cost more fuel to do it that way.
Safe landing
Suppose our spacecraft and crew get to Mars. The next challenge is landing.
A spacecraft entering Earth is able to use the drag generated by interaction with the atmosphere to slow down. This allows the craft to land safely on the Earth's surface (provided it can survive the related heating).
But the atmosphere on Mars is about 100 times thinner than Earth's. That means less potential for drag, so it isn't possible to land safely without some kind of aid.
Some missions have landed on airbags (such as NASA's Pathfider mission) while others have used thrusters (NASA's Phoenix mission). The latter, once again, requires more fuel.
Life on Mars
A Martian day lasts 24 hours and 37 minutes but the similarities with Earth stop there.
The thin atmosphere on Mars means it can't retain heat as well as Earth does, so life on Mars is characterised by large extremes in temperature during the day/night cycle.
Mars has a maximum temperature of 30?, which sounds quite pleasant, but its minimum temperature is -140?, and its average temperature is -63?. The average winter temperature at the Earth's South Pole is about -49?.
So we need to be very selective about where we choose to live on Mars and how we manage temperature during the night.
The gravity on Mars is 38% of Earth's (so you'd feel lighter) but the air is principally carbon dioxide (CO2) with several percent of nitrogen, so it's completely unbreathable. We would need to build a climate-controlled place just to live there.
SpaceX plans to launch several cargo flights including critical infrastructure such as greenhouses, solar panels and - you guessed it - a fuel-production facility for return missions to Earth.
Life on Mars would be possible and several simulation trials have already been done on Earth to see how people would cope with such an existence.
Return to Earth
The final challenge is the return journey and getting people safely back to Earth.
Apollo 11 entered Earth's atmosphere at about 40,000km/h, which is just below the velocity required to escape Earth's orbit.
Spacecraft returning from Mars will have re-entry velocities from 47,000km/h to 54,000km/h, depending on the orbit they use to arrive at Earth.
They could slow down into low orbit around Earth to around 28,800km/h before entering our atmosphere but - you guessed it - they'd need extra fuel to do that.
If they just barrel into the atmosphere, it will do all of the deceleration for them. We just need to make sure we don't kill the astronauts with G-forces or burn them up due to excess heating.
These are just some of the challenges facing a Mars mission and all of the technological building blocks to achieve this are there. We just need to spend the time and the money and bring it all together.
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@ps3linux @Hamartia Antidote @Fawadqasim1
Just some technical facts.
