Transit 3B was an American satellite which was launched in 1961 and operated by the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

. It was a replacement for Transit 3A, which was lost in a launch failure the previous year. It carried instruments to demonstrate navigation and timing systems, and study geodesy to support the development of the

Transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

satellite navigation system. The launch of Transit 3B was conducted at 03:45 UTC on 22 February 1961, using a Thor DM-21 Ablestar rocket flying from Launch Complex 17B at the

Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the statio ...

. The LOFTI-1 satellite was launched aboard the same rocket. The rocket and upper stage used had the serial numbers Thor 313 and Ablestar 007 respectively. The launch resulted in a partial failure, with the spacecraft being placed in a more

eccentric Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

orbit than planned, and failing to separate from the upper stage. Transit 3B was a spacecraft, which was powered by 6,600 solar cells charging a nickel-cadmium battery. It ended up in a

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...

with a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of , an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of , and 28.3 degrees of

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

. It had an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of 96.4 minutes. Due to the low perigee of its orbit, Transit 3B decayed quickly, and reentered the atmosphere on 30 March 1961, less than 37 days after launch. Despite being in the wrong orbit and operating for less time than had been planned, some useful data was returned from the mission. The systems demonstrated by Transit 3B included a digital clock to control timing signals, uploading programs into the onboard computer's memory whilst in orbit, data retention and FM encoding, and the use of

phase modulation Phase modulation (PM) is a modulation pattern for conditioning communication signals for transmission. It encodes a message signal as variations in the instantaneous phase of a carrier wave. Phase modulation is one of the two principal forms of ...

for data transmission without affecting the satellite's Doppler signal. The satellite's computer had a memory capacity of 48 bytes.

References

Spacecraft launched in 1961 Partial satellite launch failures Spacecraft which reentered in 1961 Navigation satellites {{US-spacecraft-stub