‘Sitting On A Controlled Explosion’: 25 Years Since the Space Shuttle’s Half-Century Mission


Endeavour roars aloft, 25 years ago, this week, for the Space Shuttle’s 50th flight. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

Twenty-five years ago, this week, Space Shuttle Endeavour—the youngest member of NASA’s fleet of orbiter vehicles, built to replace the ill-fated Challenger—rocketed away from the Kennedy Space Center (KSC) in Florida, on a mission of many firsts. Her crew included the first Japanese citizen to fly aboard a U.S. spacecraft, the first married couple to fly together on the same space mission and the first African-American female astronaut. And despite its numerical designation of “STS-47”, Endeavour’s second flight was actually the 50th mission of the 30-year Space Shuttle Program (SSP).

At this point, a little over a decade since the first shuttle flight and six years since the untimely loss of Challenger, the program had accomplished a number of spectacular successes in scientific research, satellite deployment and retrieval and spacewalking. International astronauts had flown shoulder-to-shoulder with their U.S. counterparts and, for the first time, women and ethnic minorities had flown routinely into orbit. The presence of Mae Jemison on STS-47 as the first African-American female astronaut was not lost on U.S. Vice President Dan Quayle, who was watching the launch on 12 September 1992 from the Firing Room in Florida. After chatting for a few moments with STS-47 Commander Robert “Hoot” Gibson, Quayle offered greetings to Jemison. A few months earlier, he had visited the newly-opened Mae C. Jemison Academy in Detroit, Mi.

The multi-faceted crew of STS-47. Photo Credit: NASA

The payload for the planned seven-day mission was Spacelab-J, a joint venture between the U.S. and Japanese space agencies, with a research emphasis on the life and microgravity sciences. Like several previous Spacelab missions, the seven-member crew was divided into two 12-hour shifts, in order that they could run the experiments around-the-clock. The “red” team of Gibson, Pilot Curt Brown, Payload Commander Mark Lee and Japan’s Mamoru Mohri were awakened at 4:58 a.m. EDT on launch morning, with the “blue” team of Mission Specialists Jemison, Jay Apt and Jan Davis rose about a half-hour later.

After breakfasting in the Operations & Checkout Building, the seven spacefarers donned their bright-orange pressure suits and headed out to the launch pad, where Endeavour waited for them. Liftoff at 10:23 a.m. was picture-perfect and within nine minutes the shuttle had settled smoothly into a 57-degree-inclined orbit at an altitude of 160 miles (260 km). For three members of the crew, the launch was not a new experience, but for Brown, Davis, Mohri and Jemison, it was their first flight into space.

“You are aware that you are sitting on a controlled explosion,” Jemison recounted, years later. “But you also realize that you’ve taken all the precautions. You trust the people you have been working with and you know they have worked to try to keep things safe. After that, you have to leave it alone. If you keep worrying about it, then you’re not going to be able to do your job.”



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  1. As time goes by the more obvious the flaws in the space shuttle become and the more perplexed contemporary space enthusiasts are at it being built in the first place.

    I remember the 1st flight quite well because I was in Korea on the DMZ as a young soldier. Some things don’t change. We all watched it in the NCO club. Mostly because of one soldier who was so excited about it he infected the rest of us. He thought it was the beginning of a new space age. I was not even interested in space at the time. Not until 2003 when I was helping my wife research a college paper did I become fascinated with space travel.

    Sadly, it was not the second space age. I have since come to the conclusion that LEO stopped being “space exploration” in 1968 when Apollo 8 left Earth orbit far behind. The space age actually ended in 1972 with the last Apollo mission. So what to call Skylab and the shuttle program and everything since Apollo 17 splashdown?

    I guess “interregnum” would be the best term. This interregnum will end when that first SLS crew achieves escape velocity and heads for the Moon.

    • “This interregnum will end when that first SLS crew achieves escape velocity and heads for the Moon.” – MichaelatNASA


      Sailing a small boat in a harbor or being docked or anchored in a harbor certainly isn’t an ocean voyage. However, many useful and needed things are done in the safety of a harbor.

      I’ve done both harbor and beyond the harbor sailing and have been on some deep sea voyages and seen more than enough seasick folks puking over the side of a ship.

      Most ships have their crews changed or given a rest, get resupplied, and are loaded with money making cargo in the safe shelter of a harbor.

      Our LEO and low orbit harbors around the Moon and Ceres are useful and so are our robotic and human voyages across deep space.


      Jeff Bezos and Blue Origin want the Moon and a whole lot more.

      “Moreover, New Glenn is also, as Bezos repeated Tuesday, ‘the smallest orbital rocket Blue Origin will ever build.’ In the future, even larger boosters are coming, such as the previously teased New Armstrong rocket. The tech mogul has recently said that lunar exploration is the next logical step for human activity in space.”

      From: ‘Blue Origin releases details of its monster orbital rocket’ By Eric Berger 3/7/2017
      At: https://arstechnica.com/science/2017/03/blue-origin-releases-details-of-its-monster-orbital-rocket/

      Our politicians want the Moon and a whole lot more.

      “(e) Pioneering doctrine.—Congress declares that the general welfare of the United States requires that the unique competence in scientific and engineering systems of the Administration also be directed toward the pioneering of space. The objectives of such pioneering shall be to increase access to destinations in space, explore the possible options for development at these destinations, demonstrate the engineering feasibility of such development, and transition those activities to Federal agencies outside of the Administration or persons or entities outside of the Federal Government.”

      From: ‘H.R.4945 – American Space Renaissance Act’
      At: https://www.congress.gov/bill/114th-congress/house-bill/4945/text#toc-H60AB63261FD244228E2BDDFC4D6A10F4

      Lots of folks will soon be leaving the safe harbor of LEO.

    • “Now in his third term in the U.S. House of Representatives, Bridenstine has demonstrated an extraordinary interest in American space programs, both military and civilian. He is the author and sponsor of a bill called the American Space Renaissance Act, an ambitious re-imagining of America’s space program and a re-writing of the agency’s charter around the ‘Pioneering Doctrine.'”

      And, “An administrator with a clear vision oriented toward the creation of new capabilities is a good first step toward fixing NASA’s problems. Jim Bridenstine needs to be rapidly confirmed by the Senate. The sooner he gets on the job, the better for America’s future in space.”

      From: ‘A Pioneering NASA Administrator’ By Paul D. Spudis September 13, 2017
      At: http://www.airspacemag.com/daily-planet/pioneering-nasa-administrator-180964885/

      “But Seattle billionaire Jeff Bezos has a different kind of off-Earth home in mind when he talks about having millions of people living and working in space. His long-range vision focuses on a decades-old concept for huge artificial habitats that are best known today as O’Neill cylinders.”

      And, “The idea is to create cylinder-shaped structures in outer space, and give them enough of a spin that residents on the inner surface of the cylinder could live their lives in Earth-style gravity. The habitat’s interior would be illuminated either by reflected sunlight or sunlike artificial light.”

      From: ‘Where does Jeff Bezos foresee putting space colonists? Inside O’Neill cylinders’
      By Alan Boyle on October 29, 2016
      At: https://www.geekwire.com/2016/jeff-bezos-space-colonies-oneill/

      Great things usually require lots of time, a huge pile of money, and many tons of persistence.

  2. “‘You are aware that you are sitting on a controlled explosion,’ Jemison recounted, years later.” – Ben Evans

    Perhaps it is worth noting that the future evolved SRBs for the SLS could eventually be a bit different forms of controlled explosions from the SRBs that mainly powered a Space Shuttle at launch.

    “The Naval Air Weapons Station at China Lake, California, developed a new compound, C6H6N6(NO2)6, called simply CL-20 (China Lake compound #20). Compared to HMX, CL-20 has 14% more energy per mass, 20% more energy per volume, and a higher oxygen-to-fuel ratio.”

    And, “CL-20 propellant compliant with Congress’ 2004 insensitive munitions (IM) law has been demonstrated and may, as its cost comes down, be suitable for use in commercial launch vehicles, with a very significant increase in performance compared with the currently favored APCP solid propellants. With a specific impulse of 309 s already demonstrated by Peacekeeper’s second stage using HMX propellant, the higher energy of CL-20 propellant can be expected to increase specific impulse to around 320 s in similar ICBM or launch vehicle upper stage applications, without the explosive hazard of HMX.”

    And, “An attractive attribute for military use is the ability for solid rocket propellant to remain loaded in the rocket for long durations and then be reliably launched at a moment’s notice.”

    From: ‘Solid-propellant rocket’ Wikipedia
    At: https://en.wikipedia.org/wiki/Solid-propellant_rocket

    Eventually, two Dark Knight SRBs added to the tri-core version of the Vulcan launcher or to a possible tri-core version of the Antares launcher might be interesting and useful.

    For that matter, two Dark Knight SRBs, with over 4,500,000 lbf of thrust from each SRB, added to the SLS and New Glenn launchers could also be useful.


    “In May 2015, the ULA CEO released a chart showing a potential future Vulcan Heavy three-core launch vehicle concept with 23,000 kg (50,000 lb)-payload capacity to geostationary transfer orbit, while a one-core Vulcan 561 with the ACES upper stage would have 15,100 kg (33,200 lb) capacity to the same orbit.”

    From: ‘Vulcan (rocket)’ Wikipedia
    At: https://en.wikipedia.org/wiki/Vulcan_(rocket)

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