New “Flying Tea Kettle” Could Get Us To Mars in Weeks, Not Months

At 54.6 million km away at its closest, the fastest travel to Mars from Earth using current technology (and no small bit of math) takes around 214 days — that’s about 30 weeks, or 7 months. A robotic explorer like Curiosity may not have any issues with that, but it’d be a tough journey for a human crew. Developing a quicker, more efficient method of propulsion for interplanetary voyages is essential for future human exploration missions… and right now a research team at the University of Alabama in Huntsville is doing just that.

This summer, UAHuntsville researchers, partnered with NASA’s Marshall Space Flight Center and Boeing, are laying the groundwork for a propulsion system that uses powerful pulses of nuclear fusion created within hollow 2-inch-wide “pucks” of lithium deuteride. And like hockey pucks, the plan is to “slapshot” them with plasma energy, fusing the lithium and hydrogen atoms inside and releasing enough force to ultimately propel a spacecraft — an effect known as “Z-pinch”.

“If this works,” said Dr. Jason Cassibry, an associate professor of engineering at UAH, “we could reach Mars in six to eight weeks instead of six to eight months.”

Read: How Long Does It Take To Get To Mars?

The key component to the UAH research is the Decade Module 2 — a massive device used by the Department of Defense for weapons testing in the 90s. Delivered last month to UAH (some assembly required) the DM2 will allow the team to test Z-pinch creation and confinement methods, and then utilize the data to hopefully get to the next step: fusion of lithium-deuterium pellets to create propulsion controlled via an electromagnetic field “nozzle”.

Although a rocket powered by Z-pinch fusion wouldn’t be used to actually leave Earth’s surface — it would run out of fuel within minutes — once in space it could be fired up to efficiently spiral out of orbit, coast at high speed and then slow down at the desired location, just like conventional rockets except… better.

“It’s equivalent to 20 percent of the world’s power output in a tiny bolt of lightning no bigger than your finger. It’s a tremendous amount of energy in a tiny period of time, just a hundred billionths of a second.”

– Dr. Jason Cassibry on the Z-pinch effect

In fact, according to a UAHuntsville news release, a pulsed fusion engine is pretty much the same thing as a regular rocket engine: a “flying tea kettle.” Cold material goes in, gets energized and hot gas pushes out. The difference is how much and what kind of cold material is used, and how forceful the push out is.

Everything else is just rocket science.

Read more on the University of Huntsville news site here and on al.com. Also, Paul Gilster at Centauri Dreams has a nice write-up about the research as well as a little history of Z-pinch fusion technology… check it out. Top image: Mars imaged with Hubble’s Wide-Field Planetary Camera 2 in March 1995.

Darwin vs. the Sun

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Today, we take it for granted that the Sun produces energy via nuclear fusion. However, this realization only came about in the early 1900’s and wasn’t confirmed until several decades later (see the Solar Neutrino Problem). Prior to that, several other methods of energy production had been proposed. These ranged from burning coal to a constant bombardment of comets and meteors to slow contraction. Each of these methods seemed initially plausible, but when astronomers of the time worked out how long each one could sustain such a brightness, they came up against an unlikely opponent: Charles Darwin.

In a “Catholic Magazine and Review” from 1889, known as The Month, there is a good record of the development of the problem faced in an article titled “The Age of the Sun and Darwinism”. It begins with a review of the recently discovered Law of Conservation of Energy in which they establish that a method of generation must be established and that this question is necessarily entangled with the age of the Sun and also, life on Earth. Without a constant generation of energy, the Sun would quickly cool and this was known to be unlikely due to archaeological evidences which hinted that the Sun’s output had been constant for at least 4,000 years.

While burning coal seemed a good candidate since coal power was just coming into fashion at the time, scientists had calculated that even burning in pure oxygen, the Sun could only last ~6,000 years. The article feared that this may signal “the end of supplies of heat and light to our globe would be very near indeed” since religious scholars held the age of the Earth to be some “4000 years of chronological time before the Christian era, and 1800 since”.

The bombardment hypothesis was also examined explaining that the transference of kinetic energy can increase temperatures citing examples of bullets striking metal surfaces or hammers heating anvils. But again, calculations hinted that this too was wrong. The rate with which the Sun would have to accumulate mass was extremely high. So much so that it would lead to the “derangement of the whole mechanism of the heavens.” The result would be that the period of the year over the past ~6,000 years would have shortened by six weeks and that the Earth too would be constantly bombarded by meteors (although some especially strong meteor showers at that time lent some credence to this).

The only strong candidate left was that of gravitational contraction proposed by Sir William Thomson (later Lord Kelvin) and Hermann von Helmholtz in a series of papers they began publishing in 1854. But in 1859, Darwin published the Origin of Species in which he required an age of at least two billion years. Thomson’s and Helmholtz’s hypothesis could only support an age of some tens of millions of years. Thus astronomy and biology were brought head to head. Darwin was fully aware of this problem. In a letter to a friend, he wrote that, “Thomson’s views of the recent age of the world have been for some time one of my sorest troubles”.

To back the astronomers was the developing field of spectroscopy in which they determined that the sun and other stars bared a strong similarity to that of nebulae. These nebulae could contract under their own gravity and as such, provided a natural establishment for the formation of stars, leading gracefully into the contraction hypothesis. Although not mentioned in the article, Darwin did have some support from geologists like Charles Lyell who studied the formation of mountain ranges and also posited an older Earth.

Some astronomers attempted to add other methods in addition to gravitational contraction (such as tidal friction) to extend the age of the solar system, but none could reach the age required by Darwin. Similarly, some biologists worked to speed up evolutionary processes by positing separate events of abiogenesis to shave off some of the required time for diversification of various kingdoms. But these too could not rectify the problem.

Ultimately, the article throws its weight in the camp of the doomed astronomers. Interestingly, much of the same rhetoric in use by anti-evolutionists today can be found in the article. They state, “it is not surprising to find men of science, who not only have not the slightest doubt about the truth of their own pet theories, but are ready to lay down the law in the realms of philosophy and theology, in science which with, to judge from their immoderate assertions, their acquaintance is of the most remote? Such language is to be expected from the camp-followers in the army of science, who assurance is generally inversely proportional to their knowledge, for many of those in a word who affect to popularize the doctrine of Natural Selection.”

In time, Darwin would win the battle as astronomers would realize that gravitational contraction was just the match that lit the fuse of fusion. However, we must ask whether scientists would have been as quickly able to accept the proposition of stellar fusion had Darwin not pointed out the fundamental contradiction in ages?

Why is the Sun Hot?

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The Sun is the hottest place in the Solar System. The surface of the Sun is a mere 5,800 Kelvin, but down at the core of the Sun, the temperatures reach 15 million Kelvin. What’s going on, why is the Sun hot?

The Sun is just a big plasma ball of hydrogen, held together by the mutual gravity of all its mass. This enormous mass pulls inward, trying to compress the Sun down. It’s the same reason why the Earth and the rest of the planets are spheres. As the pull of gravity compresses the gas inside the Sun together, it increases the temperature and pressure in the core.

If you could travel down into the Sun, you’d reach a point where the pressure and temperature are enough that nuclear fusion is able to take place. This is the process where protons are merged together into atoms of helium. It can only happen in hot temperatures, and under incredible pressures. But the process of fusion gives off more energy than it uses. So once it gets going, each fusion reaction gives off gamma radiation. It’s the radiation pressure of this light created in the core of the Sun that actually stops it from compressing any more.

The Sun is actually in perfect balance. Gravity is trying to squeeze it together into a little ball, but this creates the right conditions for fusion. The fusion releases radiation, and it’s this radiation that pushes back against the gravity, keeping the Sun as a sphere.

We have written many articles about the Sun for Universe Today. Here’s an article about how hot the surface of the Sun is, and here’s an article about the parts of the Sun.

If you’d like more information on the Sun, check out NASA’s Solar System Exploration Guide on the Sun, and here’s a link to the SOHO mission homepage, which has the latest images from the Sun.

We have also recorded an episode of Astronomy Cast about the Sun. Check it out, Episode 30: The Sun, Spots and All.