What is Energy?

Energy is the capacity to do work. Scientifically, there are two main categories of energy: potential energy and kinetic energy. Potential energy is the energy you get from the mass of the object and height. The higher you go, the more potential energy you have. Likewise, the heavier an object, the more energy it carries. For example, if you drop a rock on your foot from 6 inches, it wont hurt that bad. But if you drop it from 6 feet, you will probably break your foot. This is because the 6 foot rock had more energy to break your foot. What about when we move? This is what kinetic energy is: the energy from moving. If a car hits you going 1 mile per hour, you can probably walk away just fine. However, if that same car hits you going 100 miles per hour, you will probably die. Likewise, heavier moving objects also carry more energy. If I throw a pebble at a window, it probably wont break. If I throw a heavy rock at it at the same speed, it will probably break.

For something to get to space, it has to sit on top of a rocket. This rocket will of course end up traveling very fast at thousands of miles per hour very high in space. Of course, this means that we would have to use a lot of energy to get anything to space. Depending on how you calculate it, getting 1kg into low earth orbit(LEO) takes about 100MJ of energy. To compare, this is about $3 of electricity. But wait, if it only takes $3 worth of energy to put 1kg in LEO, why does space travel still cost millions of dollars? This is because the have to launch the weight of the rocket itself, which is extremely heavy. Typically, what makes it to orbit is less than 10% of the weight of the rocket!

September 8, 2015September 8, 2015 by russellphd Categories: LearningTags: energy, rocket science Leave a comment

The Perfect Rocket (Calculus based)

Over 100 years ago, Konstantin Tsiolkovsky, father of modern rocketry, derived an equation that would help lift humanity into the heavens. This is his famous rocket equation.

Newtons second law is F=ma. This can also be written intFdt=ma=dp/dt. The final speed of the rocket will be determined by the initial mass of the rocket and fuel, final mass of the rocket, the exhaust velocity, and the gravitational losses.

We will write Newtons second law as -mg=mdv/dt+vedm/dt where m is the instantaneous mass of the rocket, ve is the exaust velocity, dv/dt is the acceleration. and dm/dt is the rate of consumption of fuel. We can now divide by m on each side and multiply by dt on each side. This will result in -gdt=dv-(ve/m)dm. Now set the bounds and integrate dt from 0 to tf, dv from v0 to tf, and dm from m0 to df. This will result in -gtf=deltav +veln(mf/m0) which we can re-arrange to deltav=-veln(mf/m0)-gtf.

Lets examine this. deltav will be the change in velocity, which should be positive. Since mf/m0 is a fraction less than 1, the ln of it will be negative. Multiplying a negative by -ve will yield a positive, which is what we want. Now we take this number and subtract the velocity losses from gravity, which is gtf. This is known as the ideal rocket equation which states that the change in velocity depends on the burn time, exhaust velocity, and mass ratio of an empty to fully fueled rocket. It is called ideal because it assumes no drag and that the rocket doesn’t change direction.

September 6, 2015September 6, 2015 by russellphd Categories: LearningTags: rocket science Leave a comment

The Commercialization of Space

Every method of transportation in history has had the ultimate goal of making it available for all. For example, the invention of the wheel revolutionized transportation . It was applied to wagons, carriages, locomotives, and now automobiles and aircraft. Now, all these methods of transportation are available to everyone. This was only due to commercialization. There is only so much that the government can provide for people. So now comes the question, will there ever be a commercialization of space?

Fortunately, the answer is yes. The past 15 years has seen a huge growth in aerospace startups. However, due to the complexity of space, progress is slow. Some companies are small, such as Masten Space Systems, and others are large, such as SpaceX and Blue Origin. No matter the size of the company though, every single one shares the common goal of opening space to all. Another commonality is that they all stress the importance of reusabilty. Not a single company is planning to throw away any parts. This is the only way to make space cheap and fast enough for a commercial market.

Some notable companies are SpaceX, Blue Origin, Virgin Galactic, XCOR Aerospace, and Bigalow Aerospace. SpaceX is currently resupplying the International Space Station and will soon be ferrying astronauts to it.They have the ultimate goal of not just commercializing space, but moving life onto Mars. Other companies such Blue Origin, Virgin Galactic, and XCOR Aerospace are offering sub-orbital flights with stunning views of the Earth and the zero-g experience. But once we get to space, wouldn’t it be nice to stay there? That’s exactly what Bigalow Aerospace doing. They are building expandable space habitats for both government and commercial purposes. Who knows, maybe in 20 years we’ll able to own property or vacation in space.

September 3, 2015September 3, 2015 by russellphd Categories: Exploration, TechnologyTags: exploration, future, rocket science, space Leave a comment

50 Years of no Progress

50 years of human space flight and we are still in low Earth orbit. On July 20^th 1969, Apollo astronauts made one small step for mankind on the moon. During this era, space technology matured at an unimaginable rate. Even more amazing, this moon landing occurred only 12 years after the first artificial satellite. This meant that rocket technology was sophisticated and advanced enough back then to launch objects and people into orbit and beyond. This was over 46 years ago. In fact, a 1969 report from the Space Task Group stated that “NASA has outlined plans that would include a manned Mars mission in 1981” (hq.nasa.gov). But where are we now? We are just six scientists strong orbiting 250 miles above Earth. What happened to our space program? Why is space travel still so expensive? When are we going to be able to vacation on the moon and visit Mars? The answer is never, at least if we continue approaching space travel the way we do today.

Our current rockets are expendable, meaning that once they launch, we don’t get them back. This is something most people don’t think about because rockets have always been that way. Imagine driving a car and throwing it away after one use. Imagine flying a plane and then throwing it away after one use. That would be absurd. No one would be traveling anywhere if that were the case. Unless we suddenly discover a new technology, chemical rockets are the only things that produce enough thrust to get to space. However, if rockets became reusable, space would be revolutionized. Elon Musk, CEO of SpaceX, states that with reusable rockets, “more than a 100-fold improvement in the cost of space flight is achievable. This ratio is comparable to that of aircraft, which are, of course, highly reusable”. Imagine a rocket launch every few minutes or hours instead of the current every few weeks/months.

This has unimaginable applications ranging from business to leisure to science. Imagine the stunning views on your space vacation. Imagine being the first life a planet has seen. Imagine all the job opportunities on literally a world. Even on Earth, everyone would benefit from cheaper rockets. Any launch involving the government would use your tax dollars more efficiently. Any satellite meant for the public such as television, weather, and communication would be cheaper too. Even if building rockets were free, building it still takes weeks or months. The engines are complex and the rocket itself is the height of a tower. Having it been over 46 years since the Apollo moon landings, us still throwing away rockets is a major concern. If we don’t change now, humans will never make it to space.

August 27, 2015August 30, 2015 by russellphd Categories: TechnologyTags: exploration, progress, rocket science Leave a comment

Staging: Diet for Rockets

If you have ever watched a rocket launch either in person or online, then you have witnessed rocket staging. Staging is the only way to get the payload into orbit. Why? Even though rockets can generate millions of pounds of thrust, they also weigh millions of pounds. Our current rockets aren’t powerful enough to make it to space in one piece. Staging is really just stacking rockets on top of each other. Once the first stage uses up all its fuel, it just becomes extra weight. And when a rocket is usually a few hundred feet tall, that is a lot of weight. After the first stage separates, it falls back to Earth and the second stage ignites. This is advantageous because the upper stages already start out at a few thousand miles per hour. That’s all it is. Staging is just simply a way to get rid of extra weight.

August 26, 2015August 28, 2015 by russellphd Categories: LearningTags: rocket science, rockets Leave a comment