domingo, 4 de febrero de 2018

Martian and Lunar Colonies To Be Powered By Nuclear Energy


Composed of over 100 Viking Orbiter images, this mosaic of Mars shows the 1300-mile-long, 5-mile-deep Valles Marineris in the center of the photo, as well as the Tharsis thermal bulge that is causing volcanoes in the left-hand part of the photo and spreading the ice-cemented crust in the center. This opens the ice to the atmosphere which sublimes, triggering huge avalanches that widen these large canyons over time. The fine material, pulverized by a billion years of impacts, is blown by large dust storms to eventually settle in the higher latitudes. The ice does occasionally melt, during the slumping or during meteorite impacts, causing transient rivers and lakes which only last days to weeks before evaporating and snowing out at the poles.

The National Aeronautics and Space Administration (NASA) is developing a tiny nuclear reactor that is perfect for powering a colony on Mars or the Moon, fueling a large spacecraft to a distant star, or operating a mining operation in the asteroid belt.

In the Kilopower Fission Power Project, the reactors are designed to provide 1 to 10 kW of electrical power which could be used for more science instruments, to power electric propulsion systems, or to support human exploration or colonies on another planet. It would provide higher data rate communications with a smaller antenna, something that is more important than one might think.

NASA partnered with the Department of Energy’s National Nuclear Security Administration to develop the Kilopower reactor using existing nuclear facilities.

The prototype uses a solid cast U-235 reactor core the size of a paper-towel roll.

High-efficiency Stirling engines produce about 10 kW of electricity.


The Kilopower nuclear reactor will take advantage of active nuclear fission, passive sodium heat pipes and Stirling engines that convert heat into motion and then electricity, to increase its efficiency compared with previous power sources.

The Kilopower system has undergone several non-nuclear tests using an electrical heat source and a depleted uranium core to verify the complete non-nuclear system design.

Actual nuclear testing is ongoing at the Nevada Test Site.

In Nevada, the reactor will be fueled with the highly-enriched uranium core and re-tested using the nuclear heat source.

For the last 50 years, we have used radioisotope electric propulsion systems and radiothermal generators (RTGs) to power long missions far from the Sun, like the Voyager missions to Jupiter and beyond, or the New Horizons mission to Pluto.

Pu-238 is the best isotope, emitting steady heat from natural radioactive decay by emitting alpha particles that thermocouples then convert to electricity.

Its 88-year half-life means the missions can be long in duration.

But RTGs don’t supply enough power to support people on another planet.

It takes a lot of power to produce oxygen, water, heat, food, charge rover batteries, manufacture tools and special materials, and smelt ore for metals.


In 2010, NASA's Mars Global Surveyor took this image of Mars' ice cap, which measures about 1,000 kilometers (621 miles) across. The ice cap is made out of water ice with frozen carbon dioxide. The ripples are deep valleys covered in shadow
NASA/JPL-Caltech/MSSS

Space travel is all about mass.

You can’t travel through space without shooting out some mass really fast in the opposite direction, to get going.

Then you have to lose mass in the opposite direction to stop.

Maneuvering during the trip also takes mass.

Fuel for space travel, even to a nearby planet like the Moon or Mars, is usually the most critical aspect of any mission.

To set up an initial colony on a planet means taking even more mass if you’re going to stay any length of time.

Fossil fuels are very heavy, as is any chemical fuel.

Solar panels are not too effective with the dim light from the Sun at Mars and beyond so that many many tons of panels plus many many tons of batteries would be needed to power even a tiny colony.

On Mars, dust storms would periodically cover these panels with dust and maintaining them will be time-consuming.

They might work better for the Moon, as there is no blowing dust and it’s much closer to the Sun, but the Moon’s 336-hour-long night would require an awful lot of batteries.

There is no wind sufficient to turn turbines on Mars or the Moon.

Even with the high velocity storms on the Red Planet, the Martian atmosphere is too thin to turn anything remotely approaching a wind turbine, contrary to the well-done movie, The Martian, which had to take liberties with that particular subject to support the plot.

Although there is sufficient water for a colony on Mars, it is frozen as ice, and could not provide enough running water for hydro.

Biomass is a no-go as it will be difficult enough to produce food as the Martian regolith is not actually a soil. Lots of soil amendments will have to be taken from Earth to grow anything there.

While volcanism is still active in the Tharsis region of Mars (see figure above), there are no subsurface water convention cells needed to run a geothermal plant.

The best and only practical energy source is a small nuclear reactor.

Nuclear fuel is the most energy dense – 80,000,000 MJ/kg versus about 50 MJ/kg for petroleum, 30 MJ/kg for coal and less than 1 MJ/kg for batteries of any type.

The latter would have to be charged anyway.

This is why NASA is developing this very small nuclear reactor.

Solar and batteries will be used in conjunction, but the safety of a colony depends on having more than one energy source that is constant.

So a few Kilopower nuclear units, some solar panels and some batteries is an ideal mix (see figure above).


This artist’s concept shows four fission-based modular nuclear power stations powering a human outpost on Mars. The system could be supplemented with solar and battery arrays.

The space mining aspect of this technology is important as the commercial space sector continues to expand.

The United States Space Act (HR 2262) was unanimously passed by Congress in 2015 and recognized the right of U.S. citizens to own asteroid resources they obtain as property and encouraging commercial exploration and recovery of resources from them.

As for Mars, NASA is planning three expeditions of four to six astronauts for a stay of about 500 days.

Each expedition will land at a different location on Mars to explore the diverse terrain and environment.

The first expedition to arrive at the surface would be unmanned cargo landers, which house the power system, propellant production for getting off the planet, and the Mars Ascent Vehicle for returning to the orbiter.

The power system will initially be used to convert the Martian CO2 atmosphere into oxygen where it will then be cryogenically cooled and stored in the Mars Ascent Vehicle (MAV).

After sufficient propellant has been produced and stored in the MAV, and the Mars orbiting habitat fully checked out, the crew will leave Earth and rendezvous with a Mars Transfer Vehicle, beginning the 200-day trip to Mars.

After arriving in orbit around Mars, the crew will rendezvous with the habitat and begin the entry, descent, and landing to the pre-deployed cargo landers to start their surface mission.

Resultado de imagen para NASA/JPL-Caltech/MSS Mars’ surface looks so much like Earth, it seems likely that humans

Mars’ surface looks so much like Earth, it seems likely that humans will set foot on it. This photo by the Curiosity rover on September, 2015 shows a long ridge colored by the iron oxide mineral hematite. Just beyond is an undulating plain rich in clay minerals. Beyond that are a multitude of rounded buttes including Mount Sharp, all high in sulfate minerals. Liquid water, for some amount of time, billions of years ago, is needed to produce these rocks and minerals
NASA/JPL-Caltech/MSSS

There is an awful lot of logistics, technology and planning to be done before any mission could occur, but humans on Mars would be the greatest achievement of this century.

And nuclear power will be the energy that makes it happen.

James Conca , CONTRIBUTOR
I write about nuclear, energy and the environment 

Dr. James Conca is an expert on energy, nuclear and dirty bombs, a planetary geologist, and a professional speaker.
Follow him on Twitter @jimconca and see his book at Amazon.com

forbes.com


A NASA Funded Project Wants to Use Plasma Rockets to Get to Mars


 Ad Astra Rocket Company

IN BRIEF

A company headed by one of the most decorated astronauts in history has proposed using nuclear-heated plasma to reach Mars.

While it has been funded by NASA, is the idea viable?

Elon Musk doesn't think so

PLASMA PROPELLED ROCKETS

Ad Astra Rocket Company thinks that a plasma engine could hypothetically get us to the Red Planet in 38 days, by traveling at a speed of 115,200 mph — contrary to the mainstream idea that massive rockets are the only way.

NASA has supported the company’s plan by investing nine million dollars.



Franklin R. Chang Díaz, the CEO of Ad Astra and the man who co-holds the record for most visits to the International Space Station, plans to use plasma because it can be held in place magnetically, which means that more power can be produced because there is nothing for the fuel to melt.

However, when in space, heating fuel to this temperature would require a nuclear power source — which is where this concept gets controversial.

Elon Musk, in particular, is critical of this plan on two fronts.

First, attaching the weight of a nuclear reactor to a spacecraft, he thinks, is unfeasible.

Secondly, he believes that using nuclear fuel on a spacecraft is dangerous because radioactive debris would fall back to Earth if the system failed.

THE COSMIC COMPETITION

Recently, Stephen Hawking added his voice to the choir of intellectuals and industry leaders proclaiming that humanity must become an interplanetary species.

But with our ambition established, the question now becomes how to make it happen.

All other serious ideas of how to get to Mars propose using a chemical space rocket engine.

NASA and SpaceX have both revealed plans that use enormous rockets which carry astronauts and all of their provisions including water, air, food, and machinery.

At the more theoretical end of the spectrum are plans to use technology that, previously, has been reserved for the realms of science fiction.

Phillip Lubin has proposed using photon propulsion which, hypothetically, could get us to Mars in just three days.

The race for the red planet is well and truly on, and the winner of this 21st-century space race will be decided in the intellectual theater long before human boots touch Mars’ dusty surface.

However, according to most estimates, we will only need to wait around a decade to find out.

References: ForbesSpace.com, Johnson Space Center

WRITTEN BY

AUTHOR Tom Ward
EDITOR Chelsea Gohd
@chelsea_gohd

futurism.com


lunes, 21 de noviembre de 2016

MIT researchers think we're a step closer to practical nuclear fusion


Nuclear fission reactors have been within our grasp for 50 years now. 
Image: REUTERS/Dominick Reuter

IN BRIEFMIT researchers using the Alcator C-Mod reactor have achieved a new nuclear fusion pressure record of more than 2 atmospheres of pressure.

The Alcator C-Mod is set to retire after over 23 years of use but its nuclear fusion experiments have brought us closer to nearly unlimited clean energy.STABILIZING NUCLEAR FUSION

Nuclear fission reactors have been within our grasp for 50 years now, but harnessing the power of the Sun through stable nuclear fusion has eluded us.


Alcator C-Mod interior from A-Port
Image: MIT PSFC

Stable nuclear fusion involves a plasma’s particle density, its confinement time, and its temperature, reaching a particular value (the “triply product”) that keeps the reaction going.

The plasma must be extremely hot (more than 30 million degrees Celsius) and it needs to be stable under intense pressure while remaining in a fixed volume. Adjusting the plasma pressure is most of the challenge.

Now, thanks to scientists working on the Alcator C-Mod tokamak fusion reactor at MIT, we are a step closer to controlling it.

The team managed to set a world record for plasma pressure inside the reactor, reaching over 2 atmospheres of pressure for the first time with a temperature of over 35 million Celsius. The record was set on the Alcator C-Mod reactor’s final run, which is about to retire after 23 years of use.

Former deputy director of the Princeton Plasma Physics Laboratory, Dale Meade, says the achievement of the Alcator C-Mod program takes us a step closer to a working fusion reactor.

“The record plasma pressure validates the high-magnetic-field approach as an attractive path to practical fusion energy,” Meade said, according to MIT News.

The Alcator C-Mod — with an interior reminiscent of a corridor in the Millennium Falcon from “Star Wars” — is the only compact, high-magnetic-field fusion reactor sporting a tokamak (Russian for “toroidal chamber”).

The tokamak holds the superheated plasma in a donut-shaped chamber.




CLEANER ENERGY

Nuclear fusion is a prime candidate for producing basically unlimited clean, safe, and carbon-free energy.

Unlike nuclear fission reactors that generate radioactive waste, the nuclear energy from fusion is truly renewable and virtually pollution-free.

How it can be applied to power generation is still a subject of investigation.

The record-breaking research will be presented on Oct. 17 at the International Atomic Energy Agency Fusion Energy Conference in Kyoto, Japan by MIT’s Earl Marmar, senior research scientist and Alcator leader.

Also, the team will discuss their results during a Reddit Ask Me Anything session on Oct. 20 at 1 p.m. EDT.

This article is published in collaboration with Futurism.

Written by
Dom Galeon
weforum.org