Space Junk: A Threat To Human Spaceflights
Since the first satellite launch (Sputnik 1) in 1957, thousands of space probes, satellites and telescopes have been sent into space. Just as we have created rubbish mountains on Earth, we’ve also accumulated a blanket of junk around the Earth.
Debris around the Earth. (credit: ESA)
In 2008 – when ESA (European Space Agency) published the image above, showing how much trash there was in orbit – this subject became a concern to many countries around the world. Seven years ago, two American researchers, Donald Kessler and Philip Anz-Meador, said that by 2020 it might be not possible to perform space operations near the Earth.
Today, our planet is surrounded by around 50 thousand objects, but less than 7 thousand of these are more than 20 centimetres in size. It means, these objects are, in fact, debris of our spacecraft rather than natural moons\captured asteroids. Although most of the debris in Earth Orbit is small, it’s travelling extremely fast. Below altitudes of 2,000 km, the average relative impact speed is 36,000kmph (or 21,600 mph). A crash involving even one piece can be a major disaster.
In an attempt to solve this problem, the United States president Barack Obama added a section in the new National Space Policy (USA) dedicated to the protection of the space environment and draws attention to the dangers of space debris.
“The policy seeks to minimize the creation of new debris and also to research operations for removing debris with other countries, and so you can see how international cooperation would be a very important foundation for this aspect of the policy,” Barry Pavel, senior director for defense policy and strategy at the White House National Security Council, said during a June 28 conference call with reporters.
Despite the concern expressed by the U.S. government, no one knows exactly how and when the cleaning of the Earth’s neighbourhood will be done.
Time running for WISE
Animation of WISE in orbit. Credit; NASA
NASA’s WISE (Wide-field Infrared Survey Explorer) is beginning to heat up. The spacecraft needs to be kept at 12 Kelvin (minus 438 degrees Fahrenheit) to function normally. The spacecraft carries two coolant tanks the secondary outer tank is now empty and the craft is beginning to heat up. One infrared detector, the longest-wavelength band which is the most sensitive to head stopped producing any useful data when the craft warmed to 31 Kelvin (minus 404 degrees Fahrenheit). The primary tank which cools the other infrared detectors has a good supply of coolant left and the data quality is still high.
WISE completed its primary mission July 17, 2010. A complete scan of the entire sky in infrared light. The mission so far has taken more than 1.5 million pictures. So far WISE has uncovered 29,000 new asteroids, more than 100 near-Earth objects and 15 comets.
WISE is continuing in a second survey of one-half of the sky as planned but it is feared that the coolant will run out before that scan is finished. NASA scientists say that the scan will identify new and nearby objects, as well as show if any have changed in brightness. It may also help to confirm oddball objects picked up in the first scan.
China Maxes Out on Rocket Power
As China continues to emerge as one of the worlds superpowers and reach for the stars, it’s only natural that they reach out and develop new rockets. The current rocket in development is Long March 5. A prototype should be ready by 2012 with test flights the following year. The rocket will be ready to carry humans, modules and satellites to LEO and to geostationary orbit.
Li Tongyu who is the general manager of the marketing department at the China Academy of Launch vehicle Technology (CALT), says that engineers there are currently studying a rocket engine that is capable of generating 600 pounds of thrust. Long March 5 will only produce 120 pounds of thrust.
Li Tongyu says that rockets capable of 600 pounds of thrust are justifiable only for carrying humans to the moon.
It was also mentioned earlier in March that the next Chinese heavy launch vehicle could produce 300 pounds of thrust. This would look like Long March 5 but on a bigger scale, with one main thruster in the middle and four straps on boosters.
No one knows for sure where we will end up and weather we will explore as separate nations or as a planet. And that is what the Young Astros was set up for – to unite the next generation of space scientists throughout the world and to teach everyone to work and live in peace.
James Webb Space Telescope: Hubble’s Successor
James Webb is a infrared space telescope currently under design and construction. The telescope launch is expected to take place some time during or after 2014. It is a part of the next generation of telescopes that will take the place of famous Hubble Space Telescope. The Webb Telescope is a joint project between NASA, the European Space Agency and the Canadian Space Agency.
Full-scale model of James Webb Space Telescope (credit: Nasa)
This new telescope will study the full history of our universe: since the Big Bang until the formation of Solar System. It have four main objectives: study the first bright objects in the universe; find out how exactly the galaxies were formed; discover more about the birth and development of stars and planets; and study the physical and chemical properties of solar systems (including our own) with the hopes of finding the origins of life.
There are some similarities between Hubble and Webb – both are (or will be) are designed to improve our knowledge about stars and galaxies – but there is a big difference between the two: Webb will explore the universe mainly in the infra-red frequency range, while Hubble ‘sees’ the optical (visible) and ultra-violet range.
Webb take around 3 months after launch to take up its position in orbit and begin observations. It will orbit around 1.5 million kilometres from Earth.
With this new tool, astronomers hope to shed light on some of the questions about the universe the answers to which currently remain illusive.
You can read more about Webb here.
Apollo-Soyuz: The Historic Meeting
35 years ago, a historic meeting happened in Earth’s orbit. Two craft – Apollo (from United States) and Soyuz (from Soviet Union) – made a linkage in the space. This was the first joint mission between the American and Soviet space agencies.
Artistic impression of Apollo-Soyuz linkage (Credit: Robert McCall)
During the Cold War, United States and then-Soviet Union began a competition for the space supremacy known as Space Race: which started with the Sputnik Soviet satellite launch (in 1957) and finished with the Apollo landings on Moon (between 1969 and 1972). But after the competition came the cooperation.
The Apollo-Soyuz Test Project sent NASA astronauts Tom Stafford, Deke Slayton and Vance Brand in an Apollo Command and Service Module to meet Russian cosmonauts Aleksey Leonov and Valeriy Kubasov in a Soyuz capsule. This test had the main objective of showing that two dissimilar craft could dock in orbit.
The Apollo-Soyuz crew (Credit: NASA)
On July 17, 1975 – two days after its lauch – the spacecraft were connected. The astronaut Deke Slayton reported, “it’s been a great experience. I don’t think there’s any way anybody can express how beautiful it is up here.” They exchanged gifts and worked together until July 19, when the separation occurred.
The Apollo-Soyuz mission was very important in bringing down the barriers between the nations and in opening the door to other international missions, such as the Shuttle-Mir program and the International Space Station.
Sailing On Sunshine
Ever dreamt of traversing the stars on spaceships with glittering sails, gliding effortlessly through the void between stars? well that dream may be nearer than you think.
On the 21st of May the Japanese space agency JAXA launched the IKAROS spacecraft which stands for, Interplanetary Kite-craft Accelerated by Radiation Of the Sun, it pretty much does what it says on the tin. The IKAROS space craft was launched on H-2A rocket along with another Japanese probe Akatsuki which is heading towards Venus to carry out observations of the planet.
During the first stage of deployment the solar sails were drawn out of the container in four arm-like bundles. Credit: JAXA
The IKAROS spacecraft is a small metal disk with 4 solar sails attached to it, at first the sails were packed away to prevent damage from dust and bits of smashed up satellites as it left earths orbit, when the spacecraft reached 5000000 miles from earth which is about 8046800 Km the sails were deployed. 0.5kg weights were attached at the end of each ‘arm’ and these pulled the sails out of the canister because of the centrifugal force generated by the craft spinning at 25 rpm, this was a very tense point in the deployment of the sails as they had no solid support frames and were prone to snagging on the craft as they were released and at only 7.5 micrometers thick, 13 times thinner than a human hair, if the sails caught on any part of the craft they could tear very easily.
The final stage of deployment was when holders constraining the sails were commanded to release enabling the sails to extend to their full size which is 14 metres wide. This was a very critical part in the mission as once the sails were released a camera was ejected to take images of the sails so people on the ground could check for damage to the sails as any damage would mean that the mission would not be able to operate effectively.
Credit: JAXA
Fortunately the sails were intact and small solar cells on the sails have started to produce electricity. For the remainder of its flight towards Venus the craft will be testing the maneuverability and effectiveness of a space craft propelled by solar sails.
The next mission involving solar sails is a follow up mission also developed by JAXA which will consist of a larger probe with a sail 50 metres wide and an ion engine for extra speed, this probe will be heading to Jupiter and the Trojan asteroids and will be launched late this year.
Looking into the Past
Have you ever heard people saying big telescopes see the way galaxies looked in the early universe or even light from not long after the big bang? Your answer is probably: Wait, what? How can a telescope look into the past?!? Well it’s all a matter of speed and distance. It is true that big telescopes can see what the universe looked like not too long after the big bang, but let’s not go that far just yet.
First, let’s talk about how you see things that happened in the past every time you look up. To explain that you need to know a couple of things: 1. Space is REALLY big. Quoting from the Hitchhiker’s Guide to the Galaxy: “Space, is big. Really big. You just won’t believe how vastly hugely mindbogglingly big it is.” So, I think that makes it clear. We’ll see some numbers later on, if that makes it clearer to you. And number 2. The speed of light is limited. It might not seem like it, because when someone turns on a flashlight in the other side of the room you see the light as soon as you hear the click, and you see the switch being moved. Well, that’s not really what happens, but the time is takes the light to reach you is so small, it’s impossible to notice. Even if light were to travel around the whole Earth (around the equator) it would only take 0.1336759 seconds. But as you see it would take some time. The speed of light is approximately 299792458 m/s (meters per second). And it is the fastest anything can go (to our best knowledge of physics). It looks like a lot, and it is… for earthly distances. In the vastness of space, this limit is easily seen. Let’s see how that works.
Everything we see is because light comes to our eyes. Then the brain processes this light and we get an image of what’s out there. But then, what we see is what reaches us. So when distances are really, really big, the light we get is the light that whatever object we are watching emitted or reflected towards us a long time ago, and thus, we see it the way it was when the light was emitted.
Let’s start close to home. The closest thing to us is the moon. It is at an average distance of 385000 km from us. So light takes about 1.284 seconds to reach us. This means, that every time we look up into the sky and see the moon, we see it the way it was 1.284 seconds before. Doesn’t feel like much, but the light delay is there. Next object: the sun. It is currently about 1.521×10^8 (152 100 000) km away from us. Meaning it would take the light it emits about 8.5 minutes to reach us. So whenever you feel the warm light of the sun on you, it is because it left the sun 8.5 minutes ago, and traveled through space and reached you!
The next star in our journey would be Proxima Centauri a star at more or less 3.991×10^13 km from Earth but when you start asking people how far it is most people won’t answer in km, they will use light years. A light year is the distance light can travel in a year. And Proxima Centauri is about 4.21 light years away from us. So again whenever you look at it you see it the way it was 4.21 years ago. Now we start feeling the light delay, don’t we? Well, that is nothing yet!
Let’s see the case of Betelgeuse, that red beautiful star in the constellation of Orion. It is about 425 light years away. So as we’ve said before whenever you see it you see the way it was 425 years ago, but not only that, Betelgeuse is bound to go supernova but since we see it the way it looked 425 years ago, it might’ve already gone supernova and we won’t know until that light reaches us, if it went supernova today, then humanity wouldn’t know about it until the year 2435. Interesting, huh?
Well let’s go even further in space, and back in time. Actually, let’s go as far as we can go. The Cosmic Microwave Background.The Cosmic Microwave Background (or CMB) is radiation propagated about 380 000 years after Big Bang. Before that everything was opaque so, the first light we can see is the CMB. It is not actually visible light, we “see” it in the microwave part of the spectrum. We can talk more about it in a later post, but for now, let’s just grasp the fact that this light has been traveling for about 3 699 620 000 years, and it is reaching us, and with it we get to do great discoveries about our universe.
This is an image of the CMB taken by WMAP.
So I hope this made clear why we can, and actually every day, look into the past. If you have any questions ask in the comments and I’ll do my best to answer them. Also a huge thank you to Catherine Qualtrough (@CatherineQ on Twitter) for helping me out with a couple of things! Thanks for reading!
Faster than light travel: – Fact or Fiction?
All of us have heard at least in passing about one or more forms of faster than light (FTL) travel, but is any form even possible ?
The most common form created in science fiction and the most familiar to most of us is the hyperdrive. This method ‘works’ by generating a field or bubble around the ship, this then allows the ship to shift from normal space to ‘hyper or sub’ space. Here the normal laws of physics that prevents a ship from travelling faster than the speed of light do not apply, thus the ship can travel at FTL speeds. While in theory, this could be possible, it is currently impossible to create a field that allows this shift or event to prove that subspace even exists. So for the moment at least we are a long way from flying round the galaxies with hyperdrive enabled ships.
Another more obscure form is the use of a mass lowering field (brought forward by the “Mass Effect” games). This concept is based on the principal that an object with a lower mass requires less effort and energy to accelerate it. The principal while again possible in theory does have several problems: – 1. We don’t have anything able to lower the mass of another object. 2. For this idea to work the field would have to be very powerful to reduce the mass of the ship to almost zero and needing a massive power source. So this is another method that will probably be confined to science fiction.
Yet another method of FTL travel is the wormhole. This is used in programs such as “Stargate” and “Star Trek”. This unlike the previous two methods may actually be attainable rather easily without having to defy or escape the laws of physics. Wormholes can in theory exist and are even predicted to exist in Einstein’s theory of relativity; space and time are woven together like a fabric, a large enough mass -like a star- bends space and time. If the mass is large enough it can create a sort of tunnel connecting two parts of space potentially very far apart. The tunnel itself could be very short allowing for very large distances to be traversed with very little effort. To explain a wormhole imagine you are a worm on the surface of an apple, you want to get from one side of the apple to the other. You have two choices: you can take the long way round the surface of the apple or tunnel through it giving you a much shorter distance to travel. The tunnel you create would be a wormhole in a literal sense but this also helps to explain how a wormhole would work. Another problem with wormholes (assuming they exist) is that they are point to point. This means that a wormhole would allow you to travel from point A to point B but not allow you to stop anywhere along the way. This also means that a wormhole can’t be used to connect more that two places. Imagine a tunnel connecting one side of a large mountain range to another after the tunnel has been excavated it can’t be re dug to another part of the range -it goes from one place on one side to one place on the side, nowhere else. Despite their promise no wormhole has yet been discovered so this method is possible however limited for the reasons discussed above.
An artist's impression of wormhole travel Credit to NASA
All of the above methods are either pure fiction or not possible with current technology and at this time, there are however are few instances for you to think about …
Imagine you are on a space ship travelling at 0.6 times the speed of light (this can be shortened to c) i.e. 0.6c. Another space ship is heading towards you from the direction you are travelling also at 0.6c. From either ship the other would appear to be travelling at 1.2c! This is a matter or perspective and is a paradox of closing speed or relaitive velocity – neither ship is actually travelling faster than the speed of light but each appears to be doing so if viewed from the other. Please note this is a very crude example and does not take relativity into account which would have a significant effect at these speeds.
Another example is, as we all know, each star as viewed from Earth rotates around the sky once every twenty four hours. This would seem to show that each star is moving at many times the speed of light as they would be travelling massive distances in a single night. This too however is a matter or perspective, the Earth is rotating on its axis and it is this rotation that gives the illusion that the stars are moving impossibly fast when in fact they are not.
Unfortunately as I have said FTL travel is currently impossible and fantastical ideas such as the hyperdrive will likely forever be confined to science fiction but maybe one day we will take the first step out into the big universe using some form of FTL travel perhaps even falling through a wormhole, you never know …
