Earth is Being Photographed from Orbit…But the Views Differ

A group of Silicon Valley start-ups is attempting to create a comprehensive picture of the earth from space…In real time.

…And when we say picture…We mean video.

…And when we say video, we mean close enough to track a single car across a single highway, anywhere in the world.

The scientific appeal, from the perspective of a multitude of disciplines, is obvious. The business appeal is gigantic and the potential military application is bigger than both combined.

However, not everybody is convinced that this is a good idea…

131 ‘cubesats’ – satellite cameras (that are each about the size of a shoebox) are being primed for launch over the next 12 months. These cubesats will snap a daily photograph of the earth from space, building a Google Earth-style composite image of our home planet, the main difference being that, unlike Google Earth, this picture will update itself approximately every 24 hours.

One of the companies behind this initiative is Planet Labs, a 40-employee start-up based in San Francisco. Chief Executive and co-founder Will Marshall told BBC News that,

“We’re basically leveraging billions of Dollars that has been spent in consumer electronics to advance space exploration and the capabilities of satellites to help people on the planet,”

Certainly, the Humanitarian application is potentially groundbreaking. Such technology could possibly be used to locate missing planes (exemplified by the recent tragedy of Malaysia Airlines Flight MH370), survivors of shipwrecks (like the four missing sailors currently lost at sea) and other disasters as well.

Mr. Marshall believes that his miniature satellites are in a unique position to do a lot of good.

“Instead of seeing a hole in the Amazon a few months after trees have been taken down there, we can see it as it’s happening” he says.

The first batch of 28 cubesats (known as ‘doves’ by Planet Labs), were launched in February of this year and are currently passing over earth at a speed of around five miles a second. Amazingly, they can produce images detailed enough to pick out individual trees.

However, photographs of individuals will be deliberately obfuscated, a decision taken after privacy groups protested against being captured on camera unwillingly. 

It all sounds innocent enough, until one considers that the company is funded by venture capital and is fully expecting to turn a profit from this endeavor. Hypothetically, this means that, although certain data may be handed to Humanitarian, scientific or environmental organizations, it will also be available to the highest bidder.

In addition, Planet Labs may be looking to send only its ‘doves’ into our stratosphere, but critics are concerned that such moves are already paving the way for the hawks to join them.

Start-ups like Skybox and Canadian Urthecast are far more interested in creating satellites that relay high-definition video to their corporate creators and are capable of targeting a single car on a narrow road, or even a small group of people.

In fact, Skybox launched 24 of these fridge-sized devices last December and the prototypes are already relaying 90 second black and white clips of the earth below them. The firm is currently in the process of being acquired by Google.

For their part, Urthecast are already talking about using HD-video as a sort of CCTV for homeowners.

Frankly, this has a lot of people worried. The old saying that, ‘just because you can, doesn’t mean you should’, does, for many, apply here.

Thomas Immel, who worked for twenty years at the Space Science Laboratory at UC Berkely, compares this new initiative to the opening of ‘Pandora’s Box’ from Greek mythology. He maintains, “Some applications may be harmful or controversial”.

For all the potential good projects like this can achieve, the possible cost to personal freedom is, in many people’s humble opinion, simply too high.


What Is a Couplant?

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A couplant is a material that serves as a medium for the transmission of sound waves. Usually, couplant gel is a form of water-based substance, or a paste composed of oils or grease-like chemicals. It is placed in physical contact with a transducer that receives audio signals in the air and then coverts them to electrical impulses for transmission. Microphones and sound test equipment use couplant gel or dry couplants to facilitate this.

Ultrasonic testing of materials can also employ complete immersion of the transducer in a couplant-like water, or just a thin film of glycerin or oil between the transducer and medium being studied. Acoustic couplant is important for ultrasonic testing because air is a fairly poor medium for the transmission of sound waves in general as compared to solids. The level of energy that ultrasonic frequencies carry falls off dramatically when transmitted through air, so these materials are meant to minimize this loss.

Many conventional substances can be used as a couplant, including motor oil or even hair gel. This is because even a very thin layer of air between a transducer and sound specimen will have strong attenuation effects, and nearly any solid placed between them will reduce this. Electrical components can generate a lot of heat, however, so specially formulated couplants are designed to accommodate this.

Ultrasonic couplants in the nuclear and medical equipment industry go a step further by requiring materials that are low in halogen or sulfur compounds at less than 50 parts per million (ppm). Propylene glycol, the same material used in automotive antifreeze, is another specialty compound used. It is chemically nonreactive and can withstand temperatures of 200° Fahrenheit (90° Celsius) before undergoing thermal breakdown. Optical couplant fills another unique need. Often referred to as index matching gel, it is used in the splicing of fiber optic cable to minimize variations in the index of refraction that occur where the fibers meet, which can degrade signal transmission.

The main properties looked for in a good couplant material are its acoustic properties, corrosion inhibition, and surface wetting so that it binds well. The length of time it stays wet, known as drying time, is also important, as well as the temperature levels it can endure and its uniformity. A unique aspect of some couplant gel is that it contains a fluorescent tracer dye that glows in the ultraviolet band, which is used to monitor coverage levels.