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by Jean-Jacques Serra
listing by Gunter Krebs

The Conestoga launchers are based on a program of Space Services Inc (SSI) in the early 80ies. The company was bought by EER Systems in December 1990 and became it's Space Service Division.

Percheron project

The first achievement of SSI was a liquid rocket named Percheron. It should have been the base for a launcher series made of modules of 1.2 m diameter and 12 m high with each a motor and a propellant tank. The first Percheron rocket exploded on the first motor static test on the Matagorda island (Texas) launch pad on 5 Aug 1981.

Conestoga 1

Following this failure SSI changed to solid propulsion with missile or rocket elements already operational. For it's first test on 9 Sep 1982 the Conestoga 1 (11.5 m high, 6.5 tons) was based on a single active stage: an Aerojet M56-A1 of 207 kN (the second stage of the Minuteman 1 ICBM) also used for Aries rockets. The flight was a success and the payload was ejected at apogee (313 km).

Note: in the late 80ies SSI started working on commercial flights for microgravity experiments (Consort program). They used Starfire rockets (Canadian Black Brant 9 rockets with a Terrier missile booster).

Conestoga launchers

EER Systems stayed with the modular concept to offer a series of light launchers based on various Thiokol boosters: Castor-4, Star-37 and Star-48.

The most powerful version (Conestoga 1620) features 6 Castor-4 (4 Castor-4B and 2 Castor-4A) surrounding a Castor-4B. Four Castor are on at liftoff (first stage), two more (second stage) and the central Castor acts as the third stage. The Star 48 top stage copes with orbit injection. This launcher is 15.7 m high, 87.3 tons and can deliver 460 km in orbit (40.5°).

The first launch was a failure. There are doubts on the ability of EER to finance another flight.


Designation Length (m) Diameter (m) Mass (tons) Thrust in vaccum (kN) Burn duration (s)
Castor 4A (TX780) 8.09-9.20 1,02 11,58 436-476 53.1
Castor-4B (TX859) 8,98 1,02 11,48 429 60.9
Star -37 FM (TEM-784) 1,68 0,93 1,15 48 63,7
Star-48 (TEM-711) 2,03 1,25 2,14 66 84

Conestoga launches

# Launch id Payload Launch date Type Status (orbit in perigee x apogee x inc. x period)
1 n/a Meteor (US) 23 Oct 1995 at 22:03 UT 1620 Failure: The vehicle was destroyed 45s into the first stage burn, at an altitude of 11 km
Notes: launches from Wallops

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