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US Celebrates 50 Years of Human Space Flight

04/30/2011 10:02AM

US Celebrates 50 Years of Human Space Flight
Fifty years ago, astronaut Alan B. Shepard, Jr. became the first American in space. At exactly 9:34 a.m. EST on May 5, 1961, about 45 million Americans sat tensely in front of their black and white television sets and watched a slim Redstone booster rocket with a small and cramped Mercury spacecraft manned by Alan Shepard, lift off its pad at Cape Canaveral and go roaring upward through the clear blue sky. Shepard's capsule, named Freedom 7, made an historic 15-minute suborbital flight, officially kicking off manned Project Mercury flights. With six manned flights from 1961 to 1963, Project Mercury's objectives were very specific: 1) to orbit a manned spacecraft around Earth, 2) to investigate man's ability to function in space, and 3) to recover both man and spacecraft safely -- a set of objectives it achieved with flying colors, thus opening the door for Projects Gemini and Apollo later in the decade.

The formal countdown and preparation for launching MR-3 started on the previous day. The countdown was actually split into two parts because previous experience had shown that it was preferable to run the countdown in two shorter segments and allow the launch crew of both the spacecraft and the launch vehicle to obtain some rest before starting the final preparation. The countdown started at 8:30am EST on May 4, 1961. All operations proceeded normally and were completed ahead of schedule. A build-in hold of approximately 15 hours was called at T minus 6 hours 30 minutes. During this time the spacecraft and the hydrogen peroxide propellant system was serviced.

The countdown was resumed at T minus 6 hours 30 minutes at 11:30pm EST on May 4, 1961. A built-in hold of 1 hour had been previously agreed upon at T minus 2 hours 20 minutes. This hold was to assure that spacecraft preparations had been completed before the astronaut was transported to the pad. The countdown proceeded with only minor delays until T minus 2 hours 20 minutes. At that time, final preparation of the spacecraft was conducted and the astronaut was apprised of the continuance of the countdown and transported to the Pad.

The countdown was continued after the hold at T minus 2 hours 20 minutes and, except for some minor holds, the countdown continued until T minus 15 minutes. At this time it was determined that photographic coverage of the launch and flight could not be obtained because of low clouds near the launch area. Weather forcasters predicted that visibility would improve rapidly within 20 to 45 min. During this time, one of the 400hz power inverters to the launch vehicle had regulation problems. The count was recycled to the T minus 35 minute and holding. The count picked up 86 minutes later after the replacement of the inverter.

Again at T minus 15 minutes it was necessary to hold the count again to make a final check of the real-time trajectory computer. The countdown then picked up and proceeded until liftoff at 9:34am EST on May 5, 1961.

In this historic 15 minute, 28 second flight, Alan Shepard reached an altitude of 116.5 statute miles and a velocity of 5,134 mph.

After the flight of Freedon 7, there remained no doubt that man could function intelligently aboard the Mercury spacecraft and with relative safety in a true space environment for 15 minutes.

What of the primitive spacecraft that he had inhabited? How well did it perform? The answer seemed to be very well indeed. But could its systems be trusted to work under even more demanding conditions in orbital flights? These were only a few of the questions that remained to be answered in subsequent Project Mercury flights.


For more information:

http://www.astromart.com/news/news.asp?news_id=1167

http://www.astromart.com/news/news.asp?news_id=875

http://www-pao.ksc.nasa.gov/history/mercury/mr-3/mr-3.htm

http://www.nasa.gov/externalflash/alan_shepard_gallery/index_noaccess.html

http://science.ksc.nasa.gov/history/mercury/mr-3/mr-3.html

http://www.hq.nasa.gov/office/pao/History/SP-4201/toc.htm

http://www.hq.nasa.gov/office/pao/History/SP-4201/ch11-4.htm


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