THE SUB-ORBITAL MERCURY FLIGHTS

The “stepping stones to space” process of developing the Space Shuttle from the rocket planes and lifting bodies had its precedent in the ballistic capsule programmes. Unmanned variants were tried out in pad aborts, sub-orbital and orbital missions, before committing them to manned missions. In Russia, dogs were used in the Vostok (and Voskhod) programme as test subjects prior to sending cosmonauts into space, while in the United States, primates performed a similar function for the Mercury programme. These “animal space explorers” paved the way for humans to venture into space by qualifying launch, orbital and entry systems and flight profiles. Though several biological payloads and research subjects have been flown on other missions, never again have animal tests preceded human flights in order to qualify new space­craft variants.

One way to qualify human flight systems prior to committing to a more challeng­ing orbital mission was by means of a “sub-orbital” flight – essentially a simple boosted ascent and almost immediate re-entry and landing. This profile was first proposed in both the Russian and American programmes, but the Russians abandoned the idea in favour of securing orbital flight prior to the Americans. The Americans went through with their sub-orbital test, but reduced the number of flights from seven to three, and finally two when they proved so successful. Though the two astronauts (Alan Shepard and Gus Grissom) surpassed 185 km (well over the FAI or USAF criteria), they did not enter orbit, both making only 15-minute “space flights” with about 5 minutes in weightlessness. All the record books accredit these two flights as “official space flights” as do we, but we have categorised them in this chapter as part of the “quest for space”.

MERCURY REDSTONE 3

None – sub-orbital flight 5 May 1961

Pad 5, Cape Canaveral, Florida 5 May 1961 Atlantic Ocean

Redstone No. 7; capsule no. 7 15 min 28 sec Freedom 7

First sub-orbital test of Mercury spacecraft with a human occupant; first US manned ballistic space flight

Flight Crew

SHEPARD, Alan Bartlett Jr., 38, USN, pilot