ATS-4 (Applications Technology Satellite) also known as ATS-D was a

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth ...

launched by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

on August 10, 1968 from

Cape Canaveral , image = cape canaveral.jpg , image_size = 300 , caption = View of Cape Canaveral from space in 1991 , map = Florida#USA , map_width = 300 , type = Cape , map_caption = Location in Florida , location ...

through an

Atlas-Centaur The Atlas-Centaur was a United States expendable launch vehicle derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station (CCAFS) in Florida. Early development Convair, ...

rocket.

Objectives

The objective of ATS-4 was to investigate the possibilities of a gravity gradient stabilization system (the method of stabilizing artificial satellites).

Features

The satellite has a cylindrical shape with a diameter and height (about considering the motor cover) with the surface covered by

solar panel A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...

s, and stabilized by

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

gradient.

Instruments

A total of four experiments were conducted during the mission: * Microwave Transponder * Gravity

Gradient In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gr ...

Stabilization * Image Orthicon (Day/Night) Camera * Ion Thruster

Mission

The Atlas and Centaur stages performed satisfactorily and placed the Centaur/ATS-4 in an elliptical

parking Parking is the act of stopping and disengaging a vehicle and leaving it unoccupied. Parking on one or both sides of a road is often permitted, though sometimes with restrictions. Some buildings have parking facilities for use of the buildings' ...

orbit, the Centaur stage, however, failed to re-ignite after a 61-minute coast. The failure was determined to be caused freezing of the hydrogen peroxide supply lines to the Centaur engines. High

atmospheric drag In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding flu ...

due to the low altitude of the achieved orbit precipitated the

orbital decay Orbital decay is a gradual decrease of the distance between two orbiting bodies at their closest approach (the periapsis) over many orbital periods. These orbiting bodies can be a planet and its satellite, a star and any object orbiting it, or ...

of the spacecraft, yet, still achieved good results in some of the experiments. The primary objective to put a spacecraft stabilized by gravity gradient in orbit was not reached. The satellite reentered the atmosphere on 17 October 1968.

References

External links

ATS, Past NASA Missions

ATS, NASA Science Missions
{{Orbital launches in 1968 1968 in spaceflight Applications Technology Satellites