Science and Technology Class 04

 Science and Technology Class 04

Clarification for Last Class

• The payload capacity of GSLV Mk II is 6000 kg( For Low earth orbit)

Space Missions of ISRO 

• Past Missions: Chandrayaan 1, Astrosat, Mars Orbital Mission, Chandrayaan 2
• Near Future Mission: Aditya L1, Gaganyaan, Chandrayaan 3
• Mission by End of Decade: Mars Orbital Mission 2, Shukrayaan, Xposat, Space Station

Aditya L1 Mission

• Aditya refers to the fact that it is a solar mission. L1 refers to lagrangian point 1.
• It is ISRO's first dedicated solar observatory which will study the outermost layers of the sun, i.e. Photosphere, Chromosphere, and corona.
• These layers will be studied in multiple wavelengths like visible light, ultraviolet light, infrared light, and X-rays.
• It will carry seven payloads with the following objectives:
• (a) To study solar Corona and the mechanism of coronal mass ejection.
• (b) To study the variation of solar wind properties.
• (c) To understand the heating mechanism of the solar corona.
• (d) To measure the strength of solar particles as they travel through the interplanetary region.
• (e) Aditya Mission is going to be kept at Lagrange point 1, about 1.5 million km away from earth, towards the sun.
• 
• A very powerful solar flare can be a cause of concern because it can lead to power outages, can destroy satellites functioning and we can witness auroras not just on poles, but at other latitudes as well.
• Solar Corona is the aura of plasma that extends millions of km into the sky.
• Plasma is the fourth state of matter, which exists at very high temperatures. At such high temperatures, electrons come out of the atom and coexist together with positive ions.

Lagrangian Points and Halo Orbits 

• 
• Three body problems i.e. three objects of comparable mass, and their movement only because of gravitational attraction are very complex to analyze.
• Lagrange found an exception, if the third object is very small, compared to the other two massive objects, then we can find five special points in space.
• At these five points, the third smaller object can maintain a stable orbit.
• However, the required centripetal force will come from, the combined gravitational effect of two heavier objects.
• For any two gravitationally bound systems, we can get five Lagrange points.
• For example, Sun-earth, Earth-Moon, Sun-Jupiter, etc.
• The unique characteristic of Lagrange point is that they can be orbited around.
• Thus Aditya's mission will orbit around L1, which is approximately 1.5 million km away from the earth towards the sun. This orbit is called the Halo orbit.
• The actual orbit around the sun will be a complicated three-dimensional orbit.
• This is because, the L1 point itself is revolving around the sun, along with Earth's revolution.
• The benefit of the L1 point is, that we can continuously monitor the sun without any eclipse and at the same time, can maintain the communication channel with earth.
• NASA has a famous mission called SOHO around L1.
• L2 point is suitable for astronomy. It is also 1.5 million km from earth, however, opposite to the sun earth direction.
• A telescope can observe deep space without coming into the shadow of the earth or the moon.
• Here, the James Webb space telescope has been placed. It is a collaboration between, NASA, the European space agency, and the Canadian space agency.
• L3 is not very useful, because it always remains behind the sun.
• While L1, L2, and L3 are semi-stable, L4 and L5 are examples of stable equilibrium. In the future, they will also be useful.

Gaganyaan Mission

• ISRO is planning for a manned space mission for the first time.
• A group of three astronauts will spend 5-7 days, in low earth orbit
• before the manned mission, two missions will be launched to check the feasibility of the manned mission.
• Challenges to Gaganyaan Mission
• (a) When all stages of the rocket, separate properly and the orbital module carrying astronauts will be safely ejected into orbit, one part of the mission will become successful.
• (b) Spending time in space in microgravity conditions, with no safety from cosmic radiation, and a limited supply of food, water, and oxygen will be very challenging.
• (c) reentry into the atmosphere will generate a lot of heat and will require precision.
• A small error can end in a disaster.
• (d) There is always a debate about such costly missions vs, the social sector expenditure.
• Benefits of the Gaganyaan Mission
• There are both tangible and non-tangible benefits
• (a) Research and development into space lead to many spin-off technologies.
• For example, Remote surgery, laser surgery, to enhance the shelf life of food (for astronauts), use of thermal-resistant materials, and some sewage treatment plans, among many others, have various applications on earth, developed because of space research.
• (b) ISRO can become a key player in space tourism, which is an emerging economic sector.
• (c) ISRO aims to build a space station. A successful manned mission will be the first step in this direction.
• (d) India projects its space capabilities as soft power. A successful manned mission will further enhance this capability.
• (e) It will inspire the younger generation to pursue science and technology.

The topics for the next class: Space Debris, Nuclear technology