You Can Now Build Your Own Mars Rover for About $2500


It’s unlikely that any of us will ever set foot on Mars, but that doesn’t mean we can’t pretend. As spotted by, the Jet Propulsion Laboratory (JPL) released a blueprint for a planetary rover that hobbyists, aspiring engineers, and astronauts-at-heart can download for free.

Dubbed the Open Source Rover, it’s a simplified version of NASA’s Curiosity rover, which celebrates its sixth year on Mars on August 6. The six-wheel machine can be built for as little as $2500 using commercial off-the-shelf parts, such as an LED board, 3D-printed encoder mounts, and even an Xbox controller.

While JPL officials admit its 100-page instruction manual is “quite detailed,” they say it’s suitable for high school and college students, as well as adults—although some background in mechanical assembly, electronics, and software wouldn’t hurt.

The rover can be customized in accordance with the builder’s preference, whether that's installing RPM motors to make it go faster or adding USB cameras and solar panels.

“I would love to have had the opportunity to build this rover in high school, and I hope that through this project we provide that opportunity to others,” Mik Cox, manager of the project, said in a statement.

To download the instructions and test plans for free, visit GitHub.


Does Sound Travel Faster or Slower in Space?


Viktor T. Toth:

It is often said that sound doesn’t travel in space. And it is true … in empty space. Sound is pressure waves, that is, propagating changes in pressure. In the absence of pressure, there can be no pressure waves, so there is no sound.

But space is is not completely empty and not completely devoid of pressure. Hence, it carries sound. But not in a manner that would match our everyday experience.

For instance, if you were to put a speaker in interstellar space, its membrane may be moving back and forth, but it would be exceedingly rare for it to hit even a single atom or molecule. Hence, it would fail to transfer any noticeable sound energy to the thin interstellar medium. Even the somewhat denser interplanetary medium is too rarefied for sound to transfer efficiently from human scale objects; this is why astronauts cannot yell to each other during spacewalks. And just as it is impossible to transfer normal sound energy to this medium, it will also not transmit it efficiently, since its atoms and molecules are too far apart, and they just don’t bounce into each other that often. Any “normal” sound is attenuated to nothingness.

However, if you were to make your speaker a million times bigger, and let its membrane move a million times more slowly, it would be able to transfer sound energy more efficiently even to that thin medium. And that energy would propagate in the form of (tiny) changes in the (already very tiny) pressure of the interstellar medium, i.e., it would be sound.

So yes, sound can travel in the intergalactic, interstellar, interplanetary medium, and very, very low frequency sound (many octaves below anything you could possibly hear) plays an important role in the formation of structures (galaxies, solar systems). In fact, this is the mechanism through which a contracting cloud of gas can shed its excess kinetic energy and turn into something compact, such as a star.

How fast do such sounds travel, you ask? Why, there is no set speed. The general rule is that for a so-called perfect fluid (a medium that is characterized by its density and pressure, but has no viscosity or stresses) the square of the speed of sound is the ratio of the medium’s pressure to its energy density. The speed of sound, therefore, can be anything between 0 (for a pressureless medium, which does not carry sound) to the speed of light divided by the square root of three (for a very hot, so-called ultrarelativistic gas).

This post originally appeared on Quora. Click here to view.

How Fossil Fuel Use Is Making Carbon Dating Less Accurate Wedzinga Wedzinga

The scientific process of carbon dating has been used to determine the age of Ötzi the Iceman, seeds found in King Tutankhamun’s tomb, and many other archaeological finds under 60,000 years old. However, as SciShow points out in a recent episode, the excessive use of fossil fuels is making that method less reliable.

Carbon dating, also called radiocarbon or C-14 dating, involves analyzing the ratio of two isotopes of carbon: C-14 (a radioactive form of carbon that decays over time) and C-12 (a more stable form). By analyzing that ratio in a given object compared to a living organism, archaeologists, paleontologists, and other scientists can get a pretty clear idea of how old that first object is. However, as more and more fossil fuels are burned, more carbon dioxide is released into the environment. In turn, this releases more of another isotope, called C-12, which changes the ratio of carbon isotopes in the atmosphere and skews the carbon dating analysis. This phenomenon is called the Suess effect, and it’s been well-documented since the ‘70s. SciShow notes that the atmospheric carbon ratio has changed in the past, but it wasn’t anything drastic.

A recent study published in Nature Communications demonstrates the concept. Writing in The Conversation, the study authors suggest that volcanoes “can lie about their age." Ancient volcanic eruptions can be dated by comparing the “wiggly trace” of C-14 found in trees killed in the eruption to the reference "wiggle" of C-14 in the atmosphere. (This process is actually called wiggle-match dating.) But this method “is not valid if carbon dioxide gas from the volcano is affecting a tree’s version of the wiggle,” researchers write.

According to another paper cited by SciShow, we're adding so much C-12 to the atmosphere at the current rate of fossil fuel usage that by 2050 brand-new materials will seem like they're 1000 years old. Some scientists have suggested that levels of C-13 (a more stable isotope) be taken into account while doing carbon dating, but that’s only a stopgap measure. The real challenge will be to reduce our dependence on fossil fuels.

For more on how radiocarbon dating is becoming less predictable, check out SciShow’s video below.