Space Industry decoded -1 : Space

Quick read: New to space industry? Whether you’re from business, project management or engineering background and want to understand & talk about space with confidence, then this blog series is for you.

Photo by NASA on Unsplash

Background:

The idea behind this blog series is, to share the basics of space without diving deep into big set of equations, complex theories or intimidating jargons so that it will help better understand the industry you are working it and correlate with your work.

The objective is simple — “To share the knowledge of space in a fun & simple way possible.”

I plan to cover the basics of space in 3 to 4 medium post (or may be more, let see how it evolves).

Welcome to first series of “Space industry decoded-1”, in this first post, we will talk about,

1. What is space & Karman line?
2. Why to use space?
3. Is space environment hostile or friendly?
4. Concepts of orbit, differentiate orbit types & its applications?
5. What are Satellites & spacecrafts.

So, Let’s venture in space !!

Before getting to know what is space, we will first cover why space is used for?

1. Why use Space? (Applications)

Photo by Gabriela on Unsplash

Many of you reading this blog might be familiar with the recent Axiom 4 flight mission, which took Indian astronaut Shubhanshu Shukla to International space station (ISS). Reports estimates that Indian Space Research organization (ISRO) paid around ₹500 crore ($59m; £43m). So Space takes a lot of money and a hell lot of efforts so the reasons for going to space must be compelling, so why do we do it?

Some of major applications & reasons for space are as follows,

1. The final frontier: Humanity’s justifications for space exploration are rooted in self-interest and in curiosity. Its our curiosity that has leads us to use space as a medium to demonstrate technology and advance science otherwise unachievable on our Earth.
2. Science applications: Scientific data from satellites help us monitor the weather, combat climate change, improve agricultural productivity and ensure national security and many more.
3. Strategic value: Due to geopolitics or prestige, global space race, and national pride, many nation recognize the strategic value of space capability.

One the example of space application, how space is used in supporting United Nations (UN) Sustainable Development Goals (SDGs). This will help you understand the potential of space in a much wider sense.

2. What is space? (Karman line)

If you ask me or someone to define what is space, there is no unique answer, it all depends on our perception.

The scientists from various backgrounds perceive the notion of space through the lens of their respective fields which gives unique perspectives. Just ask yourself, you may also have a different view and thought about space.

At some point, scientists & researches need a common definition. Exactly same happened, In early 20th century (around the same time when Wright brothers invented airplane) for practical reasons it become necessary to distinguish between the ‘sky’ and ‘space’.

Thus, the concept of the Karman line emerged, it was coined by Von Kármán (a Hungarian-American aerospace engineer, who conducted groundbreaking research in aerodynamics and the physics of flight).

The Karman line is an imaginary boundary at an altitude of 100 km (62 miles) above the mean sea level, that defines the boundary between Earth’s atmosphere and the outer space.

The illustration given below , will help you better understand Karman line. Our Earth’s atmosphere is divided in various layers as shown,

• Troposphere: Altitude or height where the commercial airplanes will fly. It is also known as the lower atmosphere, almost all weather phenomenon occurs in this region.
• Stratosphere: At this altitude weather balloon fly & operate, they are generally flown for scientific reasons. Further in this region we have our Earth’s Ozone layer located.
• Mesosphere: At this altitude, the meteor showers one may see actually occur (the reason behind this phenomenon is , the dense atmosphere slow down the meteors, causing them to burn up and create the marvelous meteor showers we see in night sky).
• Thermosphere: At 100 Km or about 62 miles we have our “Karman line”, followed by International space stations (ISS) orbiting at about 400 Km.
• Exosphere: Outermost layers of Earth’s atmosphere, often referred as beginning of outer space.

3. Is space environment hostile or friendly?

As far as human & machines are concerned, there are some aspects of space environment which make it hostile. Space environment make space system design difficult. As discussed in early section, Our Earth’s atmosphere has several layers which protects us from immense amount of space radiation, charged particles, space debris etc. So from below image, you can understand “Sun” is one of the major source this radiation or charged particles.

Photo by NASA Hubble Space Telescope on Unsplash

The common characteristics of the space environment are,

• Vacuum
• Space radiation, electromagnetic radiation
• Space debris or micrometeoroids
• Atmospheric charged particles, solar wind particles
• Gravity

To better understand, I have compared the these characteristics to our earth’s environment in below table, which will clear all ambiguity. This uniqueness of space environment is what make the system designer to think, how they can make sure the developed electronics system survives this hostile environment.

So, What hazards can space environment cause to my space system? Whether you are a designer, project management or a business development professional, understand this is crucial. So let us break them down,

a. Vacuum:

• Vacuum cause outgassing effects which is nothing but the release of gases, vapors from a material into the vacuum environment. It can can deposit on satellite payloads such as camera, sensors potentially degrading its performance & leading to mission failure.
• Another phenomenon is cold welding which means spontaneous bonding of two clean metal surfaces that come into contact in the vacuum.

b. Space radiation: Radiation results in electronics parts malfunction and breakdown, degradation of solar cells and materials. If you are curious how space radiation may affect your systems, check out my previous blog post on basics of space radiation.

c. Thermal cycling: Large temperature differences, in space leads to heat shock, heat spot impacting materials & electronic systems.

d. Launch: The launch phase subjects spacecraft and satellites into high vibration, shock, acceleration loads that may affect systems and result in failure.

4. What is Orbit?

Looking at the figure below — what do you notice?

Orbit

Circles, circles all over… yes, we’re talking about orbits (In illustration above, a satellite is orbiting Earth in a circular orbit)

In simple sense, an orbit is basically a race track that a satellite or spacecraft drives around the planet.

Now you might wonder how spacecraft remains in orbit around the Earth forever ? (forever is just an notion, in reality satellite may stay in orbit for few years or decades before eventually decaying due to earth’s gravity)

The Key is “ Balance”.

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The satellite, like a stone is falling down a deep well, is in a state of continual free-fall, while moving sideways at a very high speed in space. This sideways motion creates a balance between Earth’s gravitational force and the satellite’s forward momentum , causing it to travel in a continuous curved path around the Earth instead of colliding with it.

Types of orbits

Without going deep for now, lets see how orbits are classified at high-level, Broadly orbits are classified based on,

• Shape (technically eccentricity)
• Inclination
• Altitude
• Function or application

a. Orbit classified based on shape:

Orbit can be classified based on shape which is determined by a parameter called eccentricity. Depending on the eccentricity value, orbit can be of circular, elliptical, parabolic and hyperbolic nature. However, for our discussion, we will focus only on circular and elliptical orbits as they are the commonly used orbits in space missions.

b. Orbit classified based on inclination:

Inclination is angle between the satellite’s orbital plane or orbit and earth’s equatorial plane. Orbits classified based on inclination are,

• Equatorial orbits: Orbital inclination is 0°, implies that satellite moves directly above Earth’s equator.
• Polar orbits: Orbital inclination is 90°, satellite passes over the both poles.
• Inclined orbit: Satellite’s orbital inclination lies between 0°and 90°.

Orbit type based on inclination, a: Equatorial orbit, b: Polar orbit and c: Inclined orbit.

c. Orbit classified based on altitude:

Based on altitude or height, orbits can be classified as,

1. LEO (Low Earth Orbit): 180–2000 km
2. MEO (Medium Earth orbit): 2000–35,780 km
3. HEO (High Earth orbit): ≥ 35,780 km
4. Lunar orbit: 384,000 km

Low Earth Orbit:

• As the name suggests, It is an orbit that is relatively close to Earth’s surface.
• This orbit is mostly used for satellite imaging applications, as its closeness to Earth allows for higher resolution images.
• International Space Station (ISS) also orbits in LEO.

Medium Earth Orbit:

Satellite is MEO are generally used for navigation purposes. The famous and most used navigation system “GPS” (Global positioning system) is located in this orbit.

Hight Earth orbit:

Satellites in HEO are commonly used for communication, navigation, scientific research, and military applications. The nearly unobstructed view of both Earth & deep space is achieved in this orbit, thus making it idea for astronomical observations.

Since we covered about orbits types based on altitude, here is a fun fact: Satellites in LEO moves faster than HEO, wonder why?

• The key is altitude. The height of the orbit determines how quickly satellite moves around the Earth.
• A satellite motioned is mainly governed by gravity and the closer it is to Earth, the stronger is the gravitational pull which causes the satellites to move quickly.
• Example: NASA’s Aqua satellite requires about 99 minutes to orbit the Earth at about 705 km, while a weather satellite about 36,000 km from Earth’s surface takes 23 hours, 56 minutes, and 4 seconds to complete an orbit.

d. Orbit classified based on applications:

Based on various applications, satellite orbit can be classified as

• Sun synchronous orbit (SSO)
• Geostationary orbit
• Molniya orbit

Note: There may be many other orbits based on applications, above mentioned orbits are some of commonly used orbits.

Sun synchronous orbit:

• In this orbit, the satellite always crosses over the equator at approximately the same local time each day and night.
• Scientists can compare the satellite images from the same season over several years without worrying too much about extreme changes in shadows and lighting.
• Without a SSO, it would be very difficult to track change over time. It would be impossible to collect the kind of consistent information required to study climate change applications.

Geostationary orbit

• The satellites in geostationary orbit (GEO), appear to be stationary over one fixed spot this because “it motion exactly matching Earth’s rotation”
• A geostationary orbit is a valuable for weather monitoring because satellites in this orbit provide a constant view of the same surface area. It is also used for telecommunication applications.

Molniya orbit

Molniya orbit (Imaged adapted from Wikipedia)

• The Molniya orbit combines high inclination (63.4°) with high eccentricity (0.722) to maximize viewing time over high latitudes.
• The satellite moves in an extreme ellipse with the Earth close to one edge. A satellite in this orbit takes about 12 hours to complete its orbit.
• A satellite in the Molniya orbit passes over the same path every 24 hours. This type of orbit is useful for communications in the far north or south.

How do we Launch to orbit?

Answer lies in Rockets or launch vehicle (in technical term). The choice of which launch vehicle to use generally depends on following parameters such as,

• Mass of the payload or satellite
• Orbit (ie How far from Earth, satellite needs to go)

By now, I believe that you have a better idea on what is orbit and its classifications. Now we will discuss over last topic of this blog series.

5. What are spacecrafts?

Photo by NASA Hubble Space Telescope on Unsplash

A spacecraft is basically in broader term is any vehicle or machine designed & build to explore or operate in space. Example: Axiom spacecraft that took astronauts to the ISS.

Whereas, a satellite is a type of spacecraft, with a specific task and usually a simpler purpose and they orbit around a planet.

Further, Cube satellite or CubeSat is type of satellite which is form of cube. CubeSat unit is commonly referred to as a 1U. A 1U CubeSat is a 10 cm × 10 cm × 10 cm cube with a mass of up to 2 kg.

Photo by Kevin Stadnyk on Unsplash

Recap

1. Why space is used? “Space is used for several applications such as remote sensing or Earthing observation, telecommunication etc.”
2. What Karman line? “The Karman line is an imaginary boundary at an altitude of 100 km (62 miles) above the mean sea level, that defines the boundary between Earth’s atmosphere and the outer space.”
3. What are the unique characteristics of space environment? “ Vacuum, space radiation, space debris, solar wind particles”
4. What is orbit? “An orbit is basically a race track that a satellite or spacecraft drives around the planet.”
5. What are various orbits? “ LEO, GEO, HEO, Polar orbits, equatorial orbit, Inclined orbit, circular orbit, elliptical orbit, SSO, GEO, Molniya orbits etc.”
6. What is a satellite? “a satellite is a type of spacecraft, with a specific task and usually a simpler purpose and they orbit around a planet.”
7. What is a cubesat? “ CubeSat is a satellite with fixed mass & dimension. 1U — 10x10x10 cm.

That’s all for now!! We’ll meet again in the next part of this blog series.

If you have any questions, thoughts, or feedback — feel free to share them in the comments. And if there’s a specific topic you’d like me to cover next, just drop it below!

Happy Learning!!

References

1. https://jigyasa.iirs.gov.in/Upload_Record/pdf/An_Introduction_to_Space_Exploration_TPDas.pdf
2. EPET 400: Spacecraft Mission Design EPET 400: Spacecraft Mission Design
3. https://earthobservatory.nasa.gov/features/OrbitsCatalog