Mercury-Redstone 2 

Ham – the first hominid in space

A three-year-old chimpanzee, named Ham, in the biopack couch for the MR-2 suborbital test flight. Credit: NASA

Mercury-Redstone 2 (MR-2) was launched on a suborbital flight at 16:55 UTC on January 31, 1961, from LC-5 at Cape Canaveral, Florida. The mission was to test the Mercury capsule and the launch vehicle before launching the first American astronaut. The capsule carried a chimpanzee named Ham, the first hominid in space. The capsule and Ham landed safely in the Atlantic Ocean 16 minutes and 39 seconds after launch.

   Officially, Ham was known as “Number 65” before his flight, and only renamed "Ham", after the Holoman Aerospace Medical Center, upon his successful return to Earth. He was taught to pull levers in response to the flashing light. Ham was born in July 1957 and was 3 years 8 months old at launch.

 The objectives of MR-2 were to: (1) obtain physiological and performance data on a primate in ballistic space flight; (2) qualify the Environmental Control System (ECS) and aeromedical instrumentation; (3) qualify the landing bag system; (4) partially qualify the voice communication system; (5) qualify the mechanically actuated side hatch; and, (6) obtain a closed-loop evaluation of the booster automatic abort system.

Chimpanzee Ham is fitted into his special capsule prior to flight on January 31, 1961. He did not wear the helmet on the flight. Credit: NASA/Smithsonian National Air and Space Museum, Herbert Stephen Desind Collection, NASM 9A08100

   During the flight, the thrust controller ran above nominal performance, depleting the propellant 0.5 s before deactivation of the abort pressure sensor. The abort system detected the early shutdown and aborted the spacecraft. The higher-than-normal cut-off velocity coupled with the thrust of the escape engine resulted in the capsule landing well beyond the recovery area. The abort properly signalled the requisite Mayday message to the recovery forces, putting them in motion for a computed rendezvous point further downrange.

   Because of the overperformance of the launch vehicle and the added velocity of the escape engine, MR-2 achieved a velocity of about 9,400 km/hour (as opposed to the intended 7,000 km/hour) and an altitude of 250 km (rather than 185 km). Ham's trip took 2 minutes and 24 seconds longer than intended (16 minutes and 39 seconds total flight time) and went 670 km downrange (205 km further than planned). His peak g-load during reentry was 14.7, almost 3g more than planned.

Mercury-Redstone 2 launch with chimpanzee Ham aboard. Credit: NASA

   Problems also occurred with regard to the cabin pressure when, just prior to the abort, at 2 minutes and 18 seconds into the flight, it dropped from 5.5 psi to 1 psi. The problem was ultimately traced to the air inlet snorkel valve. Vibrations had loosened the pin which held the valve closed, thus allowing the valve to open, an event which was normal only after the main parachute was deployed. Ham, inside his space suit, did not suffer from this sudden depressurization of the cabin. However, the open valve contributed to problems after splashdown. Ham's performance during the flight went well, with reaction times for his required tasks of lever pulling comparable to his pre-flight testing despite his vehicle's performance problems.

   When MR-2 splashed down no ships had yet reached the vicinity, having landed some 100 km from the nearest recovery ship, the destroyer USS Ellison. A P2V search plane located the capsule about 27 minutes after splashdown. Helicopters were dispatched from the USS Donner as at least two additional hours were still required for the Ellison to arrive. Although when the search plane had located the capsule it was floating upright, by the time the helicopters arrived they found MR-2 on its side and taking on water. It was determined that the beryllium heatshield had skipped on the water on impact, bouncing against the capsule bottom and puncturing two holes in the titanium pressure bulkhead. In addition, the plastic landing bag had worn badly, resulting in the heat shield being torn free. Water entering the cabin became worse when the capsule capsized, allowing more water to enter via the open cabin pressure valve. When the helicopter latched onto the capsule, the pilot estimated an extra load of nearly 800 pounds due to the sea water. Ham was returned safely to the USS Donner, apparently no worse for the wear.

The famous "handshake" welcome. After his flight, the seemingly unfazed chimpanzee Ham is greeted by the commander of the recovery ship, USS Donner. Credit: NASA, color correction by Andrzej Mirecki

© 2026, Andrew Mirecki