Amber Case via Flickr // CC BY-NC 2.0
Amber Case via Flickr // CC BY-NC 2.0

This Rocket Engine Design Would Turn Space Junk Into Propellant

Amber Case via Flickr // CC BY-NC 2.0
Amber Case via Flickr // CC BY-NC 2.0

With each passing year, the Earth's orbit becomes increasingly congested with hazardous space debris. The junk poses a real threat to spacecraft, and it's one that’s only expected to grow worse over time—the more debris that accumulates, the more collisions are expected to occur, eventually generating more debris and more collisions as part of a domino effect called the Kessler Syndrome. Scientists have been brainstorming ways to tackle this problem for years, and now one team from Tsinghua University in Beijing is proposing an idea for a rocket engine that converts space junk into propellant [PDF].

Spacecraft designed to rein in debris with a net or some other mechanism have been suggested in the past, but the issue has always been fuel supply. This rocket would help solve that problem by producing the energy needed to maneuver itself around via the space junk it cleared. The proposed rocket design relies on the scientific principle that any element can be transformed into a plasma of positive ions and electrons when heated at a high enough temperature. Using a net, the craft would harness debris less than 10 centimeters in size and transport it to a ball mill where it would be pulverized into a powder. The powder would then be heated and transferred to a system that separates positively charged ions from negatively charged electrons. A powerful electric field would accelerate the ions to high energy before expelling them as exhaust, thus producing thrust. 

Cornell University Library

It sounds straightforward in theory, but many of the crucial details would be harder to gauge. Factors like the size of the positive ions, the nature of the powder, and the density of the debris would all need to be calculated to get a better understanding of what type of thrust would actually be produced. And while the spacecraft would produce its own propellant, it would still require an energy source. The Tsinghua University team suggested nuclear power, but that would present an entirely new set of complications. It’s possible that the space-junk-eating engine will never make it into orbit, but it could inspire similar creative solutions to our planet’s growing space junk problem. And if worse to comes to worst, we always have giant lasers to fall back on.

[h/t: MIT Technology Review]

Why Do Astronauts Use Space Pens Instead of Pencils?

by Alex Carter

It's often said that NASA spent millions of dollars developing a pen that could write in zero gravity, while the Russians just used pencils. It was a warning about looking for a high-tech solution to a mundane problem, of American excess vs. Russian sensibility.

It's also entirely false.

To understand why NASA was so keen on a workable space pen, you have to understand that the pencil is not suited for space travel. The problem is that they have a habit of breaking, shattering, and leaving graphite dust behind. The wood, too, can make it a serious fire risk in the pressurized, oxygen-rich capsule. All of these common issues become life-threatening hazards in space.

Still, there were attempts to bring pencils into space. In 1965, the agency famously ordered 34 specially designed mechanical pencils in hopes of finding the perfect writing tool for astronauts. But at $128 each, they weren't exactly cheap, and it only got worse when the public got wind of the price. Thankfully, an alternative was not too far behind.

Astronaut Walt Cunningham, pilot of the Apollo 7 mission, uses the Fisher Space Pen while in flight.
Astronaut Walt Cunningham, pilot of the Apollo 7 mission, uses the Fisher Space Pen while in flight.

The Space Pen was invented by Paul Fisher, head of Fisher Pen Company. Unlike a typical pen, the Fisher Space Pen uses compressed nitrogen to force ink out of the nozzle, instead of using gravity to make it flow. This made it the ideal device for writing in space, while upside down, or submerged underwater. It wrote crisp and clean, without the safety concerns of a pencil.

Fisher contacted NASA to give his pens a try in 1965 and in 1967, after months of testing, they were impressed enough to bulk buy 400 of them for future missions. Contrary to those urban legends, NASA didn't commission the pen or contribute any funding to it. The Soviets soon ditched their grease pencils and were eventually buying the same Fisher pens as NASA, too. The price? After a 40 percent discount from Fisher, both space agencies were paying $2.39 a pen.

The Fisher Space Pens made their debut in 1968 on the Apollo 7 mission and have been involved in all manned missions since.

So, the short reason is that astronauts only used pencils when they were waiting for something better to come along. As soon as it did, they switched and never looked back. Even the Russians thought it was a good idea.

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New Study Says We Could Be Alone in the Universe

There's a good chance that humans are the only intelligent life in the galaxy, according to a new study submitted to the journal Proceedings of the Royal Society of London A. As Quartz reports, researchers at Oxford University's Future of Humanity Institute applied existing knowledge of biology, chemistry, and cosmology to the Drake equation (below). It was created by astronomer Frank Drake in 1961 as an attempt to calculate the number of intelligent civilizations that could be in our galaxy. He included factors like the average rate of star formation and the average lifespan of intelligent civilizations.

Image showing text of the Drake equation and explaining what each variable means
Equation: University of Rochester; Image: Hannah McDonald

They estimate there’s a 53 to 99.6 percent chance we’re alone in the galaxy, and a 39 to 85 percent chance we’re the only intelligent life to be found in the entire universe.

“Where are they?” the researchers ask, referring to the classic Fermi Paradox, which asserts that intelligent extraterrestrial beings exist and that they should have visited Earth by now. “Probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable.”

Seth Shostak doesn’t buy it. Shostak is senior astronomer at the SETI Institute, a research organization that analyzes radio signals for signs of extraterrestrial intelligence. Part of the challenge with mathematical modeling like this, Shostak says, is that the data are limited; scientists just haven’t looked at very many star systems.

“I could walk outside here in Mountain View, California and not see too many hippos strolling the streets,” he tells Mental Floss. “But it would be incorrect for me to say on that rather limited basis that there’s probably no hippos anywhere. It’s a big conclusion to make on the basis of a local observation.”

Moreover, they may not even know what to look for in the solar systems they have reviewed. The SETI Institute examines radio communications and light signals, but there’s always the possibility that an intelligent civilization has attempted to contact us using means we may not have developed or even considered yet.

The Fermi Paradox itself may be naïve in its understanding of the universe, Shostak says. “You could have said the same thing about Antarctica in the 1700s. A lot of people wondered, ‘Is there a continent down there?’ On the one hand, you could argue there was [a continent], and on the other hand, you could say, ‘Look, there’s an awful lot of water in the Pacific and the Atlantic, and there’s no continents there, so why should there be one at the bottom of the ocean?’”

In other words, any conclusions about the existence of extraterrestrial intelligence are likely to be presumptive, made before any solid data is released or discovered. The truth may be out there, Shostak says. We just haven’t found it yet.

[h/t Quartz]


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