Mariner Relay 1

A Mariner Relay satellite in orbit

**Project Rhea**

**Mariner Relay 1** was a United States spacecraft designed to test space based tracking systems for Project Rhea flights. It came from a NASA proposal to use small satellites launched by Mariner rockets to provide support for the Rhea spacecraft in orbit.

Mariner Relay 1 launched from Wallops island on October 30th 1960. It was to test it's systems with the Rhea-Colossus 2 spacecraft, however the mission failed to reach orbit. The satellite remained active for two years, providing tracking to Rhea, Wayfarer, and Navigator missions.

## Background

The Orbital Tracking Network was a series of U.S. owned and operated ground stations and tracking ships designed to track the Rhea capsule during an orbital flight. These stations would only provide communications for a few minutes before the spacecraft disappeared over the horizon. Rhea spacecraft would be out of communications for several minutes before it would connect to another station.

NASA devised a plan to launch three satellites into a Medium Earth Orbit that would track the Rhea spacecraft and relay the information back down to the ground stations. The concept was approved and plans for a modified Mariner rocket were issued.

## Satellite

The Mariner-Relay satellite was shaped like a small rectangular box. Within the box four gravity gradient booms extended outward to keep the spacecraft in a proper orientation. A set of four panels with over 2000 solar cells were placed on the satellite's surface to provide electricity. The satellite was permanently attached to the Altair-31A upper stage of the Red Mariner I rocket.

During a normal mission, the Rhea spacecraft would establish a link with one of the three relay satellites, it would communicate through that satellite until it disappeared over the horizon, Rhea would then switch to the next satellite and so on for the duration of the flight.

## Mission

### Use during Project Rhea

Mariner Relay 1 launched on October 30th 1960 on a Red Mariner I rocket from Wallops Flight Facility, and was successfully placed into orbit. This satellite was to perform a test of it's tracking equipment with the Rhea-Colossus 2 mission, that would launch in March of 1961. Rhea-Colossus 2 failed to reach orbit following a launch vehicle failure. The next mission, Rhea-Colossus 3, demonstrated the ability of the relay satellite and the two additional satellites were approved for launch.

Mariner-Relay 1 and it's siblings would support the remaining flights of Project Rhea demonstrating the value of space based communication satellites.

### Use with other NASA programs

Mariner Relay 1 was first used with NASA's ATMOS 1 mission which transmitted a series of photos to the satellite which then transmitted them to ground receiving stations.

When Rhea-Colossus 7 splashed down in the Atlantic ocean on ---- bringing Project Rhea to a close. The satellites were originally scheduled to be deactivated and left to drift in their orbits, but it was instead decided to repurpose them for NASA's future deep space missions. The relay satellites supported several Wayfarer missions to the moon and most notably the Navigator 1 & 2 missions to Mars and Venus.

Mariner Relay 1 was deactivated on May 23rd 1964 following the launch of the Constellation network.