Q1. A group of students from COEP Pune sent a small satellite _______ through ISRO in 2016.
A group of students from COEP Pune sent a small satellite Swayam through ISRO in 2016.
Updated on: 2026-03-31 | Author: Rahul Patil
A group of students from COEP Pune sent a small satellite Swayam through ISRO in 2016.
India has made remarkable progress in the science and technology of launch vehicles. Various types of launch vehicles have been developed to put satellites having weight up to 2500 kg, into all types of orbits. PSLV and GSLV are two important launchers.
The scientific and technological feats achieved by India in this field have a significant contribution to national and social development.
INSAT and GSAT satellite series is actively working in the field of telecommunication, television broadcasting and meteorological services. Availability of television, telephone and internet services all over the nation has been possible due to these satellites only.
EDUSAT satellite in this series is used especially in the field of education.
IRS satellite series is working for monitoring and management of natural resources and disaster management.
To exactly locate the position of any place on the earth’s surface in terms of its precise latitude and longitude, the IRNSS satellite series has been established.
Given: Height of the satellite above the earth’s surface (h)
= 35780 km
= 35780 × 103 m
We know that:
= 6400 × 103 m
To find: Tangential velocity of satellite (vc)
`"v"_"c" = sqrt(((6.67 xx 10^-11) xx (6 xx 10^24))/((6400 + 35780) xx 10^3))`
`= sqrt((40.02 xx 10^13)/(42180 xx 10^3))`
`= sqrt(40.02/42180 xx 10^10)`
`= sqrt (0.0009487909 xx 10^10)`
`= sqrt(9.487909 xx10^6)`
≈ `sqrt9.5 xx 10^3`
= 3.08 × 103 m/s
= 3.08 km/s
The critical velocity of the satellite is 3.08 km/s.
| High earth orbits | Medium earth orbits | |
| 1. | Height from the earth’s surface for these orbits is greater than or equal to 35780 km. | Height from the earth’s surface for these orbits is between 2000 km and 35780 km. |
| 2. | Satellites revolving in these orbits take around 24 hours to complete one revolution around the earth. | Satellites revolving in these orbits take around 2 to 24 hours to complete one revolution around the earth. |
| 3. | The satellites revolving in these orbits appear stationary with respect to earth. | The satellites revolving in these orbits do not appear stationary with respect to earth. |
| 4. | Satellites revolving in these orbits can be used for carrying signals for telephone, television etc. and also in the applications like meteorology. | Satellites revolving in these orbits can be used in the study of polar regions. |
| 5. | Example: IBEX (Interstellar Boundary Explorer) revolves in this orbit. | Examples: GLONASS (Global Navigation Satellite System) and Telstar – 1 revolve in these orbits. |
Due to internet, we can gather information about worldwide events sitting at home.
As, for the moon, both M and R are smaller than that for the earth, the combined result of a change in M and R makes the escape velocity of the moon lesser than that of the earth.
Due to space missions, the world has come closer. It has become very easy to contact a person in any part of the world within seconds.
Due to internet, every information is available at our fingertips. We can gather information about worldwide events sitting at home.
The use of satellites can give us advance alerts about various natural calamities, so that, we can take proper precautions.
During war, aerial surveillance can be used to get information about the enemy actions.
It is also possible to explore the fossil reserves and minerals in the earth. In this way, due to its innumerable applications, the space mission or space technology has become an inevitable part of the development of a nation.
The astronomical object closest to earth is the moon.
Light takes 1s to reach from the moon to the earth. It means that if one travels at the speed of light, it will take 1 s to reach the moon.
Moon
Explanation-
Moon is a natural satellite whereas other are artificial satellite.
If a spacecraft is to be sent to travel to outer space, it must have a minimum velocity of 11.2 km/s.
Escape velocity for Earth is
\[v_{esc} = \sqrt{\frac{2G M_e}{R_e}} = 11 . 2 km/s\]
Given:
Thus, the escape velocity of the planet is
India is the first country to discover the existence of water on the moon- Right
| Column-1 (Location) |
Column-2 Height from the earth’s surface (km) |
Column-3 g (m/s2) |
| Earth’s surface (average) | 0 | 9.81 |
| Mount Everest | 8.8 | 9.8 |
| Maximum height ever reached by manmade balloon | 36.6 | 9.77 |
| Orbit of a typical weather satellite | 400 | 8.7 |
| Orbit of communication satellite | 35700 | 0.225 |
High Earth Orbits
International Space Station and Hubble telescope revolve in Low earth Orbits.
High Earth Orbits, Medium Earth Orbit, Low Earth Orbits.
Polar Satellite Launch Vehicle (PSLV) is an example of a launch vehicle based on Newton’s third law.
Next to the moon, mars is the nearest celestial object to the earth.
Mangalyaan was placed into orbit around Mars by ISRO in September 2014.
ISRO’s Mangalyaan obtained very useful information about the surface of Mars and the atmosphere around it.
Consider the satellite of mass m revolving at height h around the planet of mass M and radius R with speed v as shown in the figure given above. As the satellite is moving in a circular orbit, a centripetal force acting on it is provided by the gravitational force of the planet,
i.e., `"mv"^2/"r" = "GMm"/"r"^2`
Following are a few ways to manage space debris:
The debris can be harmful to artificial satellites.
Deliberately forced reentry of a space object into the Earth's atmosphere.
Reduce the orbital lifetime of spacecraft.
Moving objects into less populated "disposal" orbits at the end of their functional lifetime.
The astronomical object closest to us is the moon.
The escape velocity on the moon is less than that on the earth- Right
The first artificial satellite Sputnik was sent to space by Soviet Union in 1957.
The first person to step on the moon is Neil Armstrong.
The function of a satellite launcher is based on Newton's second law of motion- Wrong
A manmade object revolving around a planet in a fixed orbit is known as artificial satellites.
Based on their functions, satellites are classified as following:
| Type of satellite | Function of satellite |
| Weather satellite | Study and prediction of weather |
| Communication satellite | Establish communication between different location in the world through the use of specific waves |
| Broadcast satellite | Telecasting of television programs |
| Navigational satellite | Fix the location of any place on the Earth’s surface in terms of its very precise latitude and longitude |
| Military Satellite | Collect information for security aspects |
| Earth Observation Satellite |
Study of forests, deserts, oceans, polar ice on the earth’s surface, exploration and management of natural resources, observation and guidance in case of natural calamities like flood and earthquake |
In addition to the artificial satellite, some other objects are also revolving around the earth like non-functional satellites, parts of the launcher detached during launching in the earth's orbit are called space debris.
If the height of the satellite orbit above the earth’s surface is between 2000 km and 35780 km, the orbits are called medium earth orbits.
In these orbits, the satellites complete one revolution in 2 to 24 hours.
The geostationary satellites cannot be used in the study of polar regions.
For this purpose, elliptical medium earth orbits passing over the polar region are used. These orbits are also called as polar orbits.
The space crafts in the Luna series sent by Soviet Union reached near the moon. Luna 2, launched in 1959 was first such craft. After that, till 1975, 15 space crafts made chemical analysis of the moon and also measured its gravity, density and radiations.
Last four crafts even landed on the moon and brought the samples of stones on the moon for analysis in the laboratories. All these missions were unmanned.
America also executed moon missions from 1962 to 1972. The specialty of these missions was that some of these were manned missions.
In July, 1969, Neil Armstrong became the first human to step on the moon. In 2008, Indian Space Research Organization (ISRO) successfully launched Chandrayaan- 1 and placed it into an orbit around the moon. It sent useful information to earth for about a year.
The most important discovery made during the mission was the presence of water on the moon surface. India was the first country to discover this.
Military satellite: These satellites collect information for security aspects of the nation.
Navigational satellite: These satellites help in locating any place on earth’s surface by fixing the location in terms of its precise latitude and longitude.
The working of the satellite launch vehicle is based on Newton’s third law of motion.
The launch vehicle uses a specific type of fuel which when burned, produces a gas. The gas expands due to its high temperature and is expelled forcefully through the nozzles at the rear side of the launch vehicle. As a result, a thrust acts on the vehicle, which drives the vehicle high into space.
The structure of the launch vehicle and the fuel to be used is decided by the weight of the satellite and the type of satellite orbit.
In this way, satellite launch vehicles are used to place satellites in their specific orbits.
In space, non-essential objects revolving around the earth are termed as debris in space.
Along with the artificial satellites, some other objects like nonfunctional satellites, parts of the launcher detached during launching, and debris generated due to collision of a satellite with other satellite or any other object in the space are also revolving around the earth.
This debris can collide with satellites or spacecrafts and damage them.
The launch vehicles can be used only once.
The spacecraft must escape the earth’s gravitational force to travel into outer space.
To achieve this, the initial velocity of the moving object must be greater than the escape velocity of the earth.
To overcome Earth's gravity-induced slowdown, the spaceship must maintain a velocity greater than escape velocity. This lets the spaceship keep moving away from Earth without being dragged back.
If the initial velocity is insufficient, the spacecraft will fall to Earth or stay in low orbit. The spacecraft can reach orbit or deep space by surpassing the escape velocity.
| India’s Satellite series | Launcher |
| Indian National Satellite (INSAT) | Geosynchronous Satellite Launch Vehicle (GSLV) |
| Geosynchronous Satellite (GSAT) | Geosynchronous Satellite Launch Vehicle (GSLV) |
| Indian Regional Navigation Satellite System (IRNSS) | Polar Satellite Launch Vehicle (PSLV) |
| Indian Remote Sensing Satellite (IRS) | Polar Satellite Launch Vehicle (PSLV) |