TRANSIT 4A (00116)

COSPAR: 1961-015A | Alt Name: Transit IV-A

Image

Additional Sources

Launch Details

Launch Date

June 29, 1961

Launch Site

Cape Canaveral Space Force Station

Launch Pad

LC-17B

Launch Vehicle

Thor-Ablestar

Orbital Elements

NORAD ID

00116

International Designator

1961-015A

Epoch

Sat, 04 Jul 2026 01:33:39 GMT

Apogee

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Perigee

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Inclination

66.81°

Right Ascension

209.53°

Eccentricity

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Argument of Perigee

261.89°

Period

103.42 min

Mean Motion

13.92 rev/day

Latitude

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Longitude

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Altitude

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Velocity

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Polar Plot

3D Visualization

Basic Satellite Info

Name

TRANSIT 4A

Alternative Name

Transit IV-A

Type

Payload

Status

Unknown

Owner

Bureau of Naval Weapons (BUWEPS)

Country

United States

Constellation

Transit

Related Satellites

Major Events

First satellite to carry a radioisotope thermoelectric generator (RTG) into space.

Latest TLEs

1 00116U 61015A   26185.06503909 -.00000010  00000-0  50897-4 0  9990

2 00116  66.8075 209.5291 0082323 261.8931  97.2803 13.92334592299053

Source: Celestrak

Summary

Here is a 2-3 paragraph summary of the satellite: The Transit 4A (also known as Transit IV-A) was a navigation satellite launched by the US on June 29, 1961. The satellite was part of the Transit constellation and was designed to provide navigation data for the US military. It measured approximately 0.8 meters in length and had a diameter of 1.1 meters. The Transit 4A carried a radioisotope thermoelectric generator (RTG) as its power source, which was a significant innovation at the time. The RTG used nuclear energy to generate electricity, making it the first satellite to carry such a device into space. The satellite's instrumentation included radio transmitters operating at 150 MHz and 400 MHz frequencies. The Transit 4A operated for approximately 15 months before its mission concluded, providing navigation data to the US military during that time. Its development marked an important milestone in the use of nuclear power sources in space exploration.

Physical Characteristics

Length

0.8

Diameter

1.1

Span

1.1

Dry Mass

Launch Mass

Shape

Cylindrical

Radar Cross Section

0.7486

Visual Magnitude

5.5

Color

Silver

Material Composition

Aluminum alloy structure

Technical Details

Payload

Navigation instrumentation and SNAP-3 RTG

Purpose

Navigation

Mission

Navigation

Manufacturer

Applied Physics Laboratory (APL)

Life Expectancy

Operated for approximately 15 months, providing navigation data until its mission concluded.

Bus

Transit 4

Configuration

Cylinder, RTG

Motor

N/A

Equipment

Radio transmitters operating at 150 MHz and 400 MHz for navigation signal dissemination.

Power System

Solar cells (body-mounted) and SNAP-3 RTG

ADCS

Spin stabilization

Transmitter Frequency

150 MHz, 400 MHz

Map

This tool will help you track the satellite's position and predict its upcoming passes over your location. Simply input the coordinates or click the geolocation button to get started.

Latitude

Longitude

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