All posts by Lenz

Mankind’s Next Giant Leap: Meet The Space Launch System

Space Shuttle Atlantis touches down at the John F. Kennedy Space Centre for the final time
Space Shuttle Atlantis touches down at the John F. Kennedy Space Center for the final time

On the 21st of July, 2011, Space Shuttle Atlantis landed, for the final time, on Runway 15 of the John F. Kennedy Space Center in Merritt Island, Florida at 5:57 am EDT (about 6:57 pm here in Shanghai). Atlantis’s landing marked both the end of its final mission, STS-135, to the International Space Station, and, on a much more significant level, the Space Shuttle program as a whole, concluding the program’s faithful service to the wider scientific community, and indeed, people the world over. As CAPCOM (capsule communicator) Barry Wilmore pointed out in his congratulatory remarks to Mission Commander Chris Ferguson, who had earlier commented that the shuttle had “earned its place in history” after “serving the world for over 30 years”, this marked the end of operations conducted by “this incredible spacecraft” which had “inspired millions around the globe”.

About two months later, on the 14th of September, NASA introduced the next major development in American spaceflight, a craft dubbed the “Space Launch System” (SLS), which was essentially a consolidation of the previously planned Ares I and IV craft into a singular craft for the use of cargo and crew. Unlike the Space Shuttle before it, the SLS is a heavy launch vehicle than an orbiter, sharing more similarities with the Saturn V launch vehicle, which helped send the Apollo Lunar Module escape the Earth’s gravitational influence on its way to the surface of the Moon, than the Space Shuttle, which saw most of its use in orbit around the Earth, as can be seen by the diagram below:

A diagram displaying the configuration of the Space Launch System
A diagram displaying the configuration of the Space Launch System

Unlike the Saturn V, however as explained by this article from NASA’s website, the SLS will serve as the launch vehicle for the Orion Multi-Purpose Crew Vehicle (MPCV), the craft that will carry astronauts and essential equipment on missions to celestial bodies beyond the distance of the Moon, with a yet-unspecified near-Earth asteroid and eventually, Mars, being marked as potential destinations. As a result of these lofty expectations, the SLS has thus been tooled to eventually be a significantly more powerful launch vehicle than the Saturn V, effectively being a bigger, badder version of the launch vehicle that helped put men on the moon. As this infographic at Space.com shows, the initial operational version of the launcher that will be commissioned for spaceflight in 2017 will be used primarily for missions in low-Earth orbit and deep space around Earth, and will already provide 0.4 million more kilograms of thrust than the Saturn V. This version of the SLS will have 3.8 million kg of thrust provided at launch by five RS-25D/E engines (modified versions of the Shuttle’s main engines) which provide power through the combustion of liquid hydrogen and liquid oxygen, and by two additional solid-fuel boosters, which are larger, longer versions of the shuttle’s boosters due to these boosters carrying more fuel (an aluminum perchlorate composite mixture) for combustion upon launch. The final operational version of the SLS will have 4.2 million kg of thrust at launch (0.8 million kg more than the Saturn V), with the further 0.4 million kg of thrust in comparison to the initial version being provided by an additional liquid-fuel (liquid hydrogen and oxygen) J-2X engine, derived from the engines used on the Saturn V itself. This final configuration, which currently does not have a defined period of operation, will be the launch vehicle used in the missions to near-Earth asteroids and Mars, the latter of which is slated to be conducted by 2030.

There are a number of implications to the development of the SLS, both to me personally and on a wider scope. In the grand scheme of things, the SLS provides the means for NASA to take the next great leap into the manned exploration of the Solar System, having the capacity to potentially take man far beyond the orbit of the Earth to places yet uncharted. The manned exploration of Mars will mark the next significant milestone in mankind’s exploration of the cosmos, as it will show that we do indeed have the capacity to visit worlds far beyond the influence of our planet and return. This will perhaps pave the way for the eventual extraterrestrial survival of the human race via the establishment of colonies on other worlds than the Earth some day, making a dream of many science-fiction fans everywhere a reality.

An artists depiction of the SLSs potential destinations
An artist's depiction of the SLS's potential destinations

On a personal level, the thought that I could actually be seeing a man set foot on Mars in person before the end of the century as a result of the SLS is a prospect that I will undoubtedly be looking forward to experiencing. While I wasn’t alive (as far as I know, anyway) to witness the Moon landing in 1969, the exhilaration, awe and indeed relief that I recall seeing on long-time CBS News Anchor Walter Cronkite’s face while watching archival footage of the landing on Youtube is an image that ingrained itself into my brain, for to me, it represents a feeling I someday hope to experience too. It was a childhood dream of mine to someday work for NASA and help with a manned mission to Mars. A dream that was fueled by many hours playing with a Lego “Mission to Mars” playset, and a dream that, due to many a struggle with the evil forces of Algebra 2/Trig, was ultimately laid to rest. While it was perhaps not my calling to work in the aeronautics industry, this childhood dream of mine instilled in me an appreciation of the stars above, and indeed, for the innovation and creativity of the men and women involved in the name of advancing the field of astronomy. I, for the past 13 or 14 years of my life, have been continually amazed by NASA and its achievements, which they have done on an approximate annual budget of around 17 billion USD as of 2007, a whopping 0.58% according to this article at The Space Review. The fact that this agency stands before us today with the potential means of sending man farther from home to other, more distant worlds in our Solar System in the name of advancing our knowledge of the cosmos and perhaps, one day ensuring the long-term survival of our race on what is essentially a pittance of an annual budget, is something that should not be understated. Take a moment and think about this, just what could NASA achieve with a higher allocation of the federal budget?

Citations:

Braukus, Michael, J.D. Harrington, and Josh Byerly. “NASA – NASA Announces Key Decision For Next Deep Space Transportation System.” National Aeronautics and Space Association, 24 May 2011. Web. 3 Nov 2011. <http://www.nasa.gov/home/hqnews/2011/may/HQ_11-164_MPCV_Decision.html>.

Brooks, Jeff. “The Space Review: Putting NASA’s budget in perspective.” The Space Review: essays and commentary about the final frontier. The Space Review, 02 Jul 2007. Web. 3 Nov 2011. <http://www.thespacereview.com/article/898/1>.

Tate, Karl. “Space Launch System: NASA’s Giant Rocket Explained (Infographic).” Space.com. N.p., 14 Sep 2011. Web. 3 Nov 2011. <http://www.space.com/12957-nasa-giant-rocket-space-launch-system-infographic.html>.

Weaver, David, Michael Braukus, J.D. Harrington, and Dan Kanigan. “NASA – NASA Announces Design for New Deep Space Exploration System.” National Aeronautics and Space Association, 14 Sep 2011. Web. 3 Nov 2011. <http://www.nasa.gov/exploration/systems/sls/sls1.html>.

Up to 11: The Science of Feedback

“Well, its one louder, isnt it? Its not ten. You see, most blokes, you know, will be playing at ten.” – Nigel Tufnel, This is Spinal Tap
“Well, it's one louder, isn't it? It's not ten. You see, most blokes, you know, will be playing at ten.” – Nigel Tufnel, This is Spinal Tap

You’ve probably heard it before. That loud, howling, bloodcurdling noise in the middle of a speech or presentation that sends everyone in the room putting their hands over their ears and recoiling away in horror, effectively bringing all activity in the room to a screeching halt (excuse the pun). That, ladies and gentlemen, is called feedback, and in the eyes of many, arguably ranks as one of the worst sounding things in the world, right up there with the sound of fingernails raking a blackboard or any one of Justin Bieber’s songs. At the same time however, have you ever found yourself listening to “My Generation” by The Who or “I Feel Fine” by The Beatles and wondered what exactly those buzzing, mechanical sounding noises that end the former and open the latter were? That too, ladies and gentlemen, is feedback, and in the hands of the right person, it can rank, to some people (myself included), as one of the most curiously cool (and somewhat mind-blowing) noises in the world. But what exactly causes feedback? And why does it sound so good in some cases and so horrible in others? That is down to the creation of a looped signal, with the creation of which being shown in the following diagram:

As can be seen here, the audio input (the things being said) that goes into the input device (the microphone) is amplified and sent back out through the output device (the speaker), through which it is then projected to the audience. However, if the amplified audio signal emitted from the speaker is picked up once again by the input device, the signal is amplified again and sent out through the output device once more, thus creating an infinite loop where the audio signal passes  (a looped signal). The howling noise that is created as a result of the establishment of the loop, however, is due to the speed by which the loop is created, as the signal generally travels fast enough for the audio signal to create its own frequency. The frequency of the howling noise is in turn affected by the distance between the input and output devices, with higher frequencies arising from a closer proximity between the input and output devices, as the signal travels faster if it has less distance to cover. The final thing to consider is the type of audio input being put into the input device in the first place. For instance, a musician deliberately trying to emanate feedback would play audio input that we deem as being generally more pleasant than perhaps, a microphone tap, thus creating a generally more pleasant sound.

But what’s the big deal? Personally, as a guy who likes listening to and discovering new music constantly, I feel that understanding how certain sounds found in music are caused is an integral part to being able to appreciate the elaborateness and ingenuity behind the sounds created by some of my favourite bands. Indeed, learning about the causes of feedback has made me come to view some of my favourite musical acts as being “scientists of sound”, generally because it has brought me to understand that some of those ethereal sounds I hear on some albums were the result of some serious manipulation of physics. In addition, it’s also brought me to realise just how much an understanding of science can help to make everyday things, such as music, seem that much more interesting, allowing me to appreciate them better. So the next time you listen to your music, just take awhile to think about what exactly the people you’re listening to are doing to create those sounds. It really does make the music that much better.

Citations:

Clark, Robert L. “What Causes Feedback in a Guitar or Microphone?: Scientific American.” Science News, Articles and Information | Scientific American. 4 Apr. 2005. Web. 14 Feb. 2011. <http://www.scientificamerican.com/article.cfm?id=what-causes-feedback-in-a>.

“HowStuffWorks “What Causes That Howling Sound in PA Systems?”” Howstuffworks “Electronics” Web. 14 Feb. 2011. <http://electronics.howstuffworks.com/gadgets/audio-music/question263.htm>.

Airbus Ain’t Got Nothing On This: The Boeing X-51

About 100 years ago, this was the pinnacle of human aviation:

US Navy Biplane circa mid 1910s to early 1920s

This was the humble biplane. The Wright Brothers famously used this particular configuration for their prototypical flying machines, in which they achieved the first “controlled heavier-than-air flight”. Compared to the hulking titanium behemoths of the modern day, the biplane looks primitive; the aviation equivalent to Picasso’s first doodles in crayon as a 3-year old. However, the biplane, like those “first doodles”, would lay the foundations for the greater works to come later, which brings us to this:

"If my calculations are correct, when this baby hits 88 miles per hour, you're going to see some serious $@#*" - Doc Brown, Back to the Future
"If my calculations are correct, when this baby hits 88 miles per hour, you're going to see some serious (stuff)" - Dr. Emmett Brown

Meet the Boeing X-51 Waverider, the product of a collaboration between Boeing, the US Air Force, NASA and a number of other organisations and corporations. The X-51 is capable of reaching Mach 6, as shown by an unmanned test run in July 2010, which makes it capable of travelling from New York to Los Angeles in 45 minutes. So what makes the X-51 capable of such astonishing speeds? The answer lies in the scramjet engines propelling the craft.

Diagram showing how a scramjet works

Diagram showing how a ramjet works

(Uppermost diagram showcases how a scramjet works, the one below that showcases how a ramjet works)

As can be seen in the two diagrams, the scramjet engine used by hypersonic aircraft such as the X-51 and the preceding ramjet run on the same principle. Air surrounding the aircraft is compressed by the aircraft’s forward motion and is sent into a combustion chamber on the aircraft’s side. Fuel is then combusted within the combustion chamber, which ignites the air flowing through the chamber, creating a thrust that allows the aircraft to travel at supersonic (and hypersonic) speeds. Ramjets however, were limited to a top speed of Mach 5, as travelling above Mach 5 caused air to be compressed too quickly, which in turn heightened air friction and temperature caused by air travelling at supersonic speeds, which would result in the aircraft crashing. To counterbalance this, scientists made modifications to the scramjet that allowed it to take in air travelling at supersonic speeds. Modifications were also made to allow for quick combustion and dispensation of combusted air from the combustion chamber, which allowed scramjet-utilising aircraft such as the X-51 to travel at their astonishing speeds.

Unfortunately for us, however, the X-51 is much too small and dangerous to ferry passengers, and hypersonic commercial aircraft is still far from being feasible. That isn’t to say, however, that hypersonic commercial aircraft are impossible, however. An article written by a person known as “Flying With Fish” on another site brought up the fact that aircraft designed for military use such as the sound barrier breaking Bell X-1 in 1947 eventually led to the development and service of the Concorde in 1969. I personally find this to be quite exciting, as it shows the possibility of commercial hypersonic flight being available in my lifetime. As a person who generally despises long-haul flights (and really, flying in general), I find the prospect of being able to be transported anywhere around the world in under 4 or 5 hours to be very exciting, as it means less time sitting on a plane being bored to tears in my seat or fearing for my life whenever a bad patch of turbulence hits. To me, this is what makes the X-51’s development such great news, as it is a true sign of things to come. Over the course of 107 years, human aviation has gone from barely being able to get off the ground to going over 6 times the speed of sound. Really, with a rate of evolution as rapid as it has been, who knows what the future holds for human aviation?

Citations:

Bonsor, Kevin. “HowStuffWorks “How Hypersonic Planes Work”” Howstuffworks “Science” Web. 27 Oct. 2010. <http://science.howstuffworks.com/transport/flight/modern/hypersonic-plane1.htm>.

McKeegan, Noel. “X-51A Waverider Breaks Supersonic Flight Record.” Gizmag | New and Emerging Technology News. 27 May 2010. Web. 27 Oct. 2010. <http://www.gizmag.com/boeing-x-51-waverider-hypersonic-flight/15241/>.

“NASA – How Scramjets Work.” NASA – Home. National Aeronautics and Space Administration, 2 Sept. 2006. Web. 27 Oct. 2010. <http://www.nasa.gov/centers/langley/news/factsheets/X43A_2006_5.html>.