SA-1 (Apollo)

Infobox Space mission
mission_name = Saturn-Apollo 1
insignia = Apollo program insignia.png sign = SA-1
launch_pad = CC LC-34
launch = October 27, 1961
15:06:04 UTC
landing = October 27, 1961
15:21:04 UTC
duration = 15 min 0 s
orbits = Suborbital
apogee = 84.6 mi (136.2 km)
distance = 206 mi (331.5 km)
mass = 52,480 kg

SA-1 was the first flight of a Saturn I launch vehicle and was part of the Apollo program.

Objectives

This was the first flight of the Saturn I booster, the first in the Saturn family, and a huge increase in size and power over anything launched before it. It was three times taller, required six times more fuel and produced ten times more thrust than the Jupiter-C rocket that had launched the first American satellite, Explorer 1 into orbit in 1958.

At this time, NASA had not decided to use all-up testing, where an entire system is tested in one go. They were planning to test each rocket stage in separate launches, so for SA-1 the only live stage was the S-1 first stage.

This first flight was designed to test the structure of the launch vehicle during a hopefully nominal, suborbital flight, carrying the nose cone from a Jupiter rocket.

Preparation

As this was the very first Saturn flight, the systems were still being developed. It would be the first time that a stage had been delivered to Cape Canaveral by barge and it would test that this could be done for the larger stages of future Saturn rockets. (At this time the Saturn V was little more than some drawings on paper.)

The first stage and the two dummy upper stages arrived on 15 August 1961 on the barge "Compromise". It had encountered some problems on the voyage, running aground four times due to poor charts. On the return trip, the barge hit a bridge, causing some minor damage.

The booster was erected at Pad 34 five days later with little trouble.

Testing proceeded, albeit a little behind schedule. At this time, testing was not automated and amounted to flicking switches in the control centre and observing how the rocket responded.

Flight

At 12:30 EST on 26 October 1961, the RP-1 propellant started to flow into the rocket. 103% of the fuel required was put into the rocket, as it was possible to easily drain fuel. Just before launch, the surplus fuel was removed from the tanks.

The liquid oxygen started flowing into its tanks at 03:00 the next day. It followed the same procedure as the RP-1 with the tanks being filled to 10% to check for leaks, then fast filled to 97%, then slowly topped up.

Despite a couple of delays due to bad weather, the rocket was launched only 1 hour behind schedule. The engineers had given the rocket only a 75% chance of actually lifting off and only a 30% chance of completing a nominal flight. Even with a nominal flight some damage was thought possible. At the Redstone Arsenal ground, testing had shattered windows 12 km away.

However, the sound of the launch was a disappointment for some witnesses, being described as like an Atlas rocket launch, when you stood at 1.5 miles (2.4 km) instead of 3 miles (5 km) for a Saturn launch. It was later decided that the cause of the difference between the Cape ground and the Redstone ground was due to atmospheric conditions damping the sound.

The flight itself was perfect. The rocket was lifted to a height of 136.5 km and impacted 345.7 km downrange from the launch site. The only real problem was the rocket cut off 1.6 seconds ahead of schedule. This was traced to the fact that there was 400 kg too much liquid oxygen and 410 kg too little RP-1. For the test flight, SA-1 only carried a propellant load that was 83% of full capacity.

External links

* [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740074734_1974074734.pdf Saturn SA-1 Flight Evaluation (PDF) December 1961]
*http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=SATURNSA1
* [http://www.hq.nasa.gov/office/pao/History/SP-4204/cover.html Moonport: A History of Apollo Launch Facilities and Operations ]
*http://science.ksc.nasa.gov/history/apollo/sa-1/sa-1.html