As America's space shuttle Columbia took off over the North Atlantic recently, technicians on the other side of the equator were preparing a Brazilian Probe 3 rocket for a routine launch over the South Atlantic.

Fired from Brazil's coastal space center at Natal, Brazil's Probe 3 missiles have attained a height of 375 miles and have reached a speed of Mach 3, or 2,235 mph.

The rocket launchings are part of a $1 billion "Complete Brazilian Space Mission" -- a program that calls for a team of 1,000 Brazilian scientists and technicians to design, build and launch four low-level orbiting satellites by 1993.

Almost 500 years after its discovery, half of Brazil's Amazon has yet to be mapped in detail, and the Brazilians now hope to learn about what is on the ground through space.

"Brazil is a continent, and we have inaccessible regions that can only be reached through satellite," says Brig. Gen. Hugo de Oliveira Piva, director of the Brazilian Air Force's Institute of Space Activities. Under Piva's direction, scientists are designing a 3 1/2-ton Probe 4 rocket, which is to rise 600 miles when launched in 1983.

Located on this city's Avenue of the Astronauts, Piva's rocket-building institute is coupled with an adjoining civilian Space Research Institute, where scientists are developing the first Brazilian-made satellites. Together, both centers could be considered the equivalent of the National Aeronautics and Space Administration. Not by chance, they are found in Sao Jose dos Campos, South America's largest center of high technology research.

From the northeastern space center at Natal, the Brazilians have launched 260 rockets in the last 10 years. But, squeezed for room and seeking a better launching pad for equatorial orbits, the Brazilian Air Force has expropriated 325 square miles for a base at Alcantara.

The new site is two degrees from the equator and 20 times larger than the Natal center. Rockets fired from Alcantara will be tracked on an eastward path from Natal, and from a new monitoring station to be installed on Fernando de Noronha, a Brazilian island in the South Atlantic.

Compared with other Third World giants, Brazil lags behind in the space race. Both India and China built and launched satellites during the 1970s. But the Brazilians say the rapid Chinese and Indian advances are military-inspired. By contrast, Brazil maintains good relations with its 10 South American neighbors and has not fought a border war in more than 100 years.

"Probe 4 could carry an atom bomb," Piva conjectured. "But it would miss. It's a very long way to accurate military use."

Instead, officials like to point to the civilian benefits promised by the four satellites -- two for data collection and two for infrared remote sensing.

Slated for launching in 1988, the first Brazilian-made satellite is to help with forecasting droughts, floods and freezes.

After the United States, Brazil is the second-largest user of NASA's Landsat photographs. But the Brazilians want to replace this foreign-controlled service with their own remote sensing satellites. Transmitted photographs will aid in measuring deforestation of the Amazon, identifying potential oil reserves, forecasting crops and map making.

Nicknamed "Brasilsat," Brazil's first communications satellite is to come from overseas. This month, officials opened bids from American, Canadian and French companies for a satellite estimated at $100 million cost, scheduled for launching in 1985.

Brazil is 25 years away from building such sophisticated hardware, but a nonnegotiable specification in the Brazilian bidding is complete technology transfer.

"We don't want to buy a black box -- we want to know how it works," said Aydano B. Carleial, in charge of developing Brazil's low-level satellites.

Critics of Brazil's space program say Brazil would save millions of dollars by buying existing foreign technology or continuing to use Landsat. The program, they say, is a waste of money for a country where two-thirds of the population does not get an adequate diet.

"We cannot be a big country without having space technology," Piva said, citing practical, money-making technological advances.

Because of space research, a Brazilian company now makes high-strength steels that are exported to the United States for use in Boeing 747 landing gear.

The most lucrative spinoff of the space research, however, is Avibras, Brazil's manufacturer of military rockets. According to the "International Defense Review," Brazil has the fifth-largest arms industry in the Western world, and, this year, Avibras expects to make and sell 20,000 rockets and bombs, without paying a dollar of royalties.

This private company markets Brazil's Probe I rocket as an air-to-land missile called the SBAT127.

This year, Avibras expects to export $20 million worth of products, and the bestselling export is the SBAT70 air-to-land rocket, which fits Soviet Migs, U.S. F5s, and British Hawker Hunters. A satisfied customer is Iraq, which ordered fresh supplies after war broke out with Iran.