Bhaskara-I and Bhaskara-II

They were two satellites for earth observation. ISRO built both.

What do the ISRO pages say?

• ISRO calls Bhaskara-I the first experimental remote sensing satellite built in India.
• Bhaskara-I was launched on 7 June 1979.
• Bhaskara-II was launched on 20 November 1981.
• Both were launched on the Soviet C-1 Intercosmos vehicle.
• Both flew in low earth orbit.

What is the memory hook?

Think “1979, then 1981”. Bhaskara-I came first, Bhaskara-II followed.

Aryabhata came first. It was India’s first satellite.

What do we know about Aryabhata?

• It was launched on 19 April 1975.
• A Soviet Kosmos-3M rocket carried it from Kapustin Yar.
• A bilateral agreement between India and the Soviet Union made this possible.
• The Soviet Union agreed to launch Indian satellites.
• It was named after the 5th century astronomer and mathematician Aryabhata.

What is the memory hook?

Think “1975, 1979, 1981”. Three launches, three steps.

ISRO gives a clear fact sheet for each satellite.

What does the ISRO table say?

• Launch date: 7 June 1979.
• Launch mass: 442 kg.
• Power: 47 W.
• It was spin stabilised.
• Orbit: 519 x 541 km, inclined at 50.6 degrees.
• It re-entered in 1989.
• Its nominal mission life was one year.

What is the memory hook?

Think “442 kg, 1979, re-entered 1989”. Ten years in orbit.

Bhaskara-II had goals similar to Bhaskara-I.

What are the Bhaskara-II numbers?

• Launch date: 20 November 1981.
• Launch mass: 444 kg.
• Power: 47 W.
• Orbit: 541 x 557 km, inclined at 50.7 degrees.
• It re-entered in 1991.
• ISRO gives it a nominal mission life of one year.

How well did it work?

• ISRO calls the operation successful during the mission life.
• One of the two cameras had a problem.
• Even so, the satellite sent more than two thousand images.
• Scientists used them for many studies.

What is the memory hook?

Think “444 kg, 1981, re-entered 1991”. Two thousand images came back.

Each satellite carried TV cameras and a radiometer.

What were the instruments?

• A two-band TV camera system.
• One band was visible light, from 0.54 to 0.66 microns.
• The other was near infrared, from 0.75 to 0.85 microns.
• The Satellite Microwave Radiometer (SAMIR) worked at 19.35, 22.235 and 31.4 GHz.

What did they study?

• The cameras served hydrology, forestry and geology.
• SAMIR studied the ocean surface.
• ISRO says Bhaskara-I’s TV images were used in hydrology and forestry.
• It says SAMIR data helped oceanographic studies.

What is the memory hook?

Think “cameras for land, SAMIR for sea”. Two tools, two jobs.

Gunter’s Space Page says the satellites are named after the two Bhaskaracharyas. These were astronomer-mathematicians of ancient India.

Where do sources differ?

• ISRO’s text says Bhaskara-II launched from Kapustin Yar.
• ISRO’s table lists Volgograd Launch Station.
• Gunter’s page lists 444 kg for the pair and orbit 512 x 557 km.
• ISRO’s pages give 442 kg and 444 kg and separate orbits.
• This lesson follows the ISRO tables for mass and orbit.

What is the memory hook?

Think “two Bhaskaras, two masses”. ISRO’s tables are the safest numbers.

Four mix-ups come up again and again. Learn each pair.

What are the traps?

• Which was first? Aryabhata (1975) was India’s first satellite. Bhaskara-I (1979) was the first experimental remote sensing satellite.
• Which orbit? Both flew in low earth orbit at about 50 degrees inclination, not in a polar orbit.
• Who launched them? The Soviet Union, on Intercosmos vehicles.
• Which date? Bhaskara-I is 7 June 1979. Bhaskara-II is 20 November 1981.

How do you remember them?

Think “1975, 1979, 1981”. Match each year to its satellite.