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Whenever we talk about designing of space technology, we think on what is it about the space that makes it require a certain label of rigor and quality, which is so designed for the use on the Earth. It mostly has to do with two things.
What does really mean by space environment?
The very first thing is space itself, which is so far, and once the technology sent to space, we cannot go there and fix it if any faults occur. So, it has to work for the first time there without any improper functioning. Needless to say, our design must be on point. We need to very mind that, we just have one chance and if we missed it, it means that we totally missed everything.
The second thing, which matters the most is the space environment itself. When we are designing Space technologies, like Satellite, Space Vehicles, Space-probes and Space-shuttles, etc., we should consider the atmospheric conditions like weather, temperature, gravity, and geomagnetic field, etc, and also we have to consider outer space conditions like a vacuum, radiation, space debris, etc. As we go up from the earth’s surface to outer space and beyond, we face many problems at different altitudes. So for this, we need to know about the space environment.
Definition of space environment
So, basically, the space environment is the branch of space science(Astronautics, aerospace, and space physics), that deals with the atmospheric and outer space conditions. The study of this helps us in knowing how these space environmental conditions can affect our Space- crafts or Space technologies.
Perturbations of Space Environment
- Radiation and
- Micrometroids and Debris
1. Atmosphere :
The atmosphere is an envelope made out of gases surrounding a star or any planetary object. These gases are held by gravity. As in launching a spacecraft from Earth, Earth’s atmosphere is something that matters.
Earth’s atmosphere is made up of layers like
- Thermosphere and
Moreover, we have an ionosphere, which is an ionized part of Earth’s upper atmospheric layer, thermosphere, but also consists of mesosphere and exosphere. The ionosphere has some effects like the temperature effect and the effect by charged particles thereby affecting the spacecraft. As we know, spacecraft has to bypass all this and must orbit at least at an altitude of 200km from Earth.
Even after the launching, there exists a problem due to atmospheric drag, which is mainly due to the density of the gases, which is capable of lowering the altitude of the space shuttle from its actual orbit.
As the altitude decreases, the density of the gases and the velocity of the space shuttle increases which would cause the space shuttle to reenter into Earth’s atmosphere causing some serious threats. So, atmospheric drag is something that has to be taken care of.
Gravity is a kind of attractive force that would pull any two objects consisting of a mass, closer. It exists everywhere in the space, as long as any object consists of mass. So, gravity basically depends on the amount of matter present and the distance between the bodies.
When we are into launching a space shuttle, it has to overcome the Earth’s gravity in the first place. In order to achieve this, our object must attain something called “escape velocity,” which is 11.2km/s for Earth. So, gravity is one factor of pulldown to the launch of the space vehicle.
Although gravitational force decreases with an increase in distance, even after the successful launching of satellites, spacecraft or ISS are not completely out of Earth’s gravity as it doesn’t fade away completely. So, gravity can still affect the surfaces of objects or satellites in its orbit, thereby causing some deviation in its path.
Space and space environment is full of charged particles, which is of excess electric charges moving in a linear or circular accelerator and guided by electromagnetic(EM) fields. Space charge is a continuum of charge, which is distributed over a region of space or in space environment. It is the most dangerous aspect of the space environment. The major sources of charge particles nearby the earth environment are:
- Solar flares and solar wind
- Galactic cosmic rays
- The Van Allen radiation
Effect of charge particles on spacecraft.
- Heating on exposed surfaces of spacecraft in space environment
- Damage exposed surfaces of space-technology
- It can also damage electrical power system components
4. Vacuum in Space
What would space actually do to a human body? In 1965, researchers at Brooks Airforce Buses in Texas exposed several dogs near to a vacuum. The dogs survived up to 90 seconds, but according to the researchers, if the dogs had been exposed for two or more minutes, they would have died when re pressurized. Researchers from NASA also did the same thing to chimpanzees in the late 1960s and found they could last up to three and a half minutes.
But, in actual space, there are even more hazards to deals with depending on the spatial location. In vacuum or empty space the average of few hydrogen atoms is per-cubic-cm. Outer space has a lack of molecules, atmosphere, and Pressure. If we introduce a molecule to an area with an atmosphere. The molecule spread-out as much as possible in order to its empty space.
Vaccum, vacant or void or devoid of matter, simply means, “the absence of matter” (or Bryonic matter) and especially the absence of air in the region. There will be no atmospheric pressure. Is our space really a perfect vacuum?
The answer is NO. Because in our solar system or in interstellar space, it contains an average of 1 atom per-cubic-cm. In intergalactic space, the presence of an average atom is 100 times lesser in-between galaxies. But according to quantum theory, the existence of virtual particles pop in and out constantly into the vacuum or empty space environment.
Effect of vacuum in outer space
What would really happen, if we step into outer space environment without any space-suit? Would our blood be boiled? Would our eyes pop out from their socket? Or would we explode?
In space or space environment, the boiling point is lower than that of the human body temperature, which means our blood would definitely boil, and due to lack of pressure, we would probably swell, up to twice the size of our body. The thing is that we won’t explode, because we would probably die in a nick of time, say around 15 seconds due to the lack of oxygen. There is also joint ball plasma that could cause a lot of damage though it is 150 million km away. UV-rays with radiation can cause cancer. There is also temperature affecting us as it is almost equal to absolute temperature.
Radiation is the emission of energy in the form of streams of particles and waves through space or any medium. This energy can exist in both form low-energy-level(like microwaves and cell phones, etc) and high-energy-level( like X-rays, gamma rays, Cosmic rays, etc) from outer space or from space Environment. these are two types.
- Ionizing (UV-rays, Xrays, gamma rays, alpha rays, GCRs rays, etc.)
- Non-ionizing radiation( Visible light, microwaves, radio waves, infrared, etc.)
Effect of radiation in the space environment
In Aug 1972, Between two apollo missions, Appollo-16(April 1972) and apollo-17(Dec 1972). Interference caused by solar activity. It’s because the sun has just erupted that is one of the most powerful solar events ever recorded. But there is no threat to humans. Because the earth’s magnetic field deflected much of the solar radiation. But the explosion is so powerful that’s disrupted Radio and Tv signals. Luckily this activity held between these apollo missions(apollo-16 and apollo-17), So, no astronauts were there in part. So thereafter NASA considers its the biggest priority to protecting the astronauts from this harmful radiation.
Biological consequences of Space-radiation are
- Solar-energetic-particles(SEPs), can penetrate your body and increase the chances of getting cancer.
- Cosmic rays are highly energetic radiation, it can break DNA causing carcinogenesis and cell death.
- Radiation can damage the central nervous system.
Effect of space radiation on space crafts
- It can disrupt radio signals.
- Electronic components can damage from total radiation dose.
- Solar arrays can lose power due to the non-ionization dose.
6. Micrometeroids and Space debris
Space debris also called Space garbage. And generally means the waste or junk around the Earth. Debris may be natural like asteroids, comets, meteoroids, and micrometeoroids or man-made ones like artificially created objects, the mass of defunct(dead spacecraft, lost equipment, boosters, weapons)
Even the smallest debris like Micrometeroids in the space can cause a huge threat to the space shuttle or ISS or satellites. The reason is that the debris moves at a speed equal to 100 times the speed of a bullet. Any object traveling at this speed would cause serious damage when it hits the surface of another object.
Debris poses a growing threat to the satellites and could prevent the use of valuable orbits in the future. This debris is mainly found in LEO and most of the satellites being launched to this orbit cause the probability of damage to increase.
Space debris is found in further orbits as well. But its density is comparatively low there. It has been estimated that at least one close approach of around 50m would take place every year in GEO, as the satellites happen to share the same orbital paths.
Methods used in tackling the debris
Some methods like
- Tug-like satellites
- Electrodynamic tethers
- Laser brooms
- Solar sails
- Space nets and collectors
have been employed to remove this debris, but many pieces of debris are too small to monitor, which would cause a large shield to the satellites