Mars Curiosity Rover

The Mars rover Curiosity is a huge leap forward from previous rover technology; this sophisticated device was created by NASA and was launched on the 26th November 2011. After its560-million-kilometer (350-million-mile) journey from Earth, the rover managed to perform some extremely complicated preprogrammed maneuvers in order to successfully land on Mars. This rover is an extremely expensive piece of technology, costing NASA some 2.5 billion dollars. This is the highest amount of money NASA has ever spent on a rover.

Curiosity’s landing in Gale Crater was called the 7 minutes of terror, because NASA would not know for 7 minutes if the landing was successful. (The signal takes 7 to 14 minutes to travel from Mars back to NASA.) NASA chose Gale Crater for a number of reasons, one of them being that it was a big and safe crater for landing.

The rover has a weight of approximately 900 kilograms (1,900 pounds).

The process of landing was as follows:

1.  Cruise stage: Curiosity approached the planet and made the final important calculations for a successful landing.
2. Cruise separation: Ten minutes before entering the Martian atmosphere, the cruise phase separated from the MSL and eventually burned up in the atmosphere.
3. Guided entry: Small rockets on the MSL craft fired to control its descent.
4. Peak heating: About eighty seconds after entering the atmosphere, the heat shield protected the MSL as it hit terminal velocity through the thickening Martian atmosphere. Temperatures reached 3,800 °F (2,100 °C).
5. Heat shield separation: Roughly 5 miles above the surface, the heat shield separated from the MSL.
6. Radar data collection: The MSL fired radar at the crater surface to determine the most suitable landing site in a predetermined zone.
7. Back shell separation: The back shell (with the parachute still attached) separated less than 2 kilometers (0.6 miles) from the surface.
8. The Sky crane lowered the rover using 3 thick metal wires.
9. Touchdown, which was obviously successful.

Overall, this rover is the most sophisticated piece of technology NASA has ever sent to Mars.

Why Is the Sky Blue?

We should begin with the Sun itself, a big hydrogen-fusing ball of plasma with a surface temperature of about 5,780 K (5,507°C or 9,944°F). At this temperature, the Sun radiates strongest in the green part of the spectrum. 

It is at this point that we can come to understand a little more about the light that the Sun is producing: It peaks in the green part of the spectrum, but a very broad range of electromagnetic radiation (light) is being given off. The Sun gives off light in a variety of forms, from X-rays and UV radiation (which causes sunburn), all the way through to radio waves. When the electromagnetic radiation eventually hits the Earth, just about the only part that doesn’t reach the surface is the X-rays, as they’re blocked by the atmosphere.

Now we’ve established that the Sun really is green, but this doesn’t really explain why the sky is blue. Or does it?

We started off at the Sun, and the next step along this little journey is the Earth’s atmosphere, where all the excitement happens.

When light enter the atmosphere, it has to pass through all the molecules it encounters. The more energetic part of the spectrum (blue) is scattered more than the less energetic (red), meaning that the less energetic light is able to pass through relatively unscathed. When the blue light is scattered it is scattered in all directions, causing the entire sky to be blue.

You might now be asking why the sky isn’t violet. We can see violet, so it is not at all unreasonable to ask this. The reason is actually somewhat related to the way that we see the Sun as being yellow as opposed to being green. Violet is the wavelength of light that is scattered the most because it is more energetic than the blue light. Our eyes, however, distinguish colour by “seeing” in three colours: red, green, and blue. This means that, to be able to see violet, we have to mix two colours together: red and blue. Since red light isn’t scattered much, there isn’t enough red for our eyes to process. This is why we don’t see the violet sky.

Mona Lisa in Space

The Mona Lisa may very well be one of the most recognizable faces in the history of humankind. And no small thanks are owed to Leonardo da Vinci (one of the most talented and celebrated painters of all time) for choosing to plaster her face on a canvas, which had an insurance assessment value of US$100 million in 1962 (US$740 million in today’s dollars). Now, Mona Lisa has gone ET. Not physically of course, but digitally.

Team members from NASA’s Goddard Space Flight Center in Greenbelt, MD, sent a digitized copy of Mona Lisa approximately 240,000 miles (390,000 kilometers) from Earth in orbit around the Moon, using a series of laser pulses, which are routinely sent to track the position of the Lunar Orbiter Laser Altimeter (LOLA) on NASA’s Lunar Reconnaissance Orbiter (LRO). The LRO has been collecting data from the lunar poles since 2009.

In order to accomplish this feat, the image was divided into 30,400 pixels, arranged as an array of 152 pixels by 200 pixels. Each pixel was converted to a shade of corresponding to a number between 0 and 4,095. At that point, each pixel was transmitted to LOLA by a laser pulse, with each pulse being fired in one of 4,096 possible time slots over the course of a brief time window, allotted for tracking the laser beams. The data was transmitted at a rate of approximately 300 bits per second, until the complete image had been sent. Then, LOLA reconstructed it using the arrival times of each of the corresponding laser pulses from Goddard.

As you can see in the first image of the Mona Lisa, portions of the transmissions we received back on Earth by radio telemetry are off; this is due in large part to unexpected turbulence in Earth’s atmosphere (the large white stripe running down the first image was created during a brief transmission pause). So the team employed Reed-Solomon coding, an error-correction algorithm often used in both CDs and DVDs to overcome some of these fluctuations (which can be seen in the second image).

Let me go ahead and mention the proverbial elephant in the room. Why do this? Why waste any time or perceived resources beaming an image to the Moon? It might sound kind of silly, but this experiment may wind up being very important in developing lasers that may be used as a backup to our current communication technology. This was the first instance that scientists have successfully achieved one-way laser communication at planetary distances, according to principal investigator David Smith of the Massachusetts Institute of Technology.

Perhaps in the future, this technology may lead the way to developing some sort of a “live” high-definition feed of distant planetary bodies in our Solar System. I don’t know about you, but I would definitely subscribe to a Jupiter-cam. She has a pretty decorated atmosphere which is always up to all kinds of interesting things.