বিভিন্ন দেশের প্রথম কৃত্রিম উপগ্রহ
Countries and Their First Satellites The launch of the Soviet Union’s Sputnik 1 satellite on October 4, 1957, marked the beginning of the Space Age. Sputnik 1 was a small, 58-centimeter-diameter aluminum sphere that weighed 83.6 kilograms. It contained four radio antennas and batteries, and it orbited the Earth every 96 minutes. Sputnik’s launch was […]