S-1D First Stage

One of the most promising developments of the Saturn V was the S-1D 1st stage.

Take the S-IC Saturn V first stage and modify the thrust structure, to turn it into a F-1 powered Super Atlas. The rocket would lift off under the power of all five F-1 engines and fly normally until 70% of the propellants were gone. Then the outer 4 engines would shut down and the engines, thrust structure, the outer skirt, fins and fairings would be jettisoned.  The center engine would continue thrusting and propel the entire S-ID stage with it's payload into orbit. The payload capacity would have been 50,000 lb.s (22,600 kg) with a 33 foot (10m) diameter payload envelope built in.  Just by itself, the S-ID could nearly match the shuttles payload at a lower cost.


For $150 million(1968) and 3 years of development, the payload capability of the entire Saturn family could have been enhanced by almost a third.  Boeing engineers had to change the thrust structure by mounting the center engine on a cylinder, attached to a new conical thrust structure on the back of the stage, to transfer the thrust to the stages skin.  The center engine would need to be able to gimbal to control the vehicle.  The outboard engine thrust structure would have been cross beams with a hollow cylinder in the center large enough to clear the center engine, by removing the cruciform where the center engine was originally mounted.  The outboard structure would made to separate from the new center structure.  The propellant lines would have needed shutdown and separation joints on the outer engines.  The IU (instrument unit) ring normally carried atop the third stage S-IVB would be reworked and mounted atop the S-ID.

The outer ring of booster engines could have been made recoverable. The payload would have been even greater had the stage's fuel tanks been enlarged as proposed for various Saturn V upgrades.  The F-1A engine with its higher thrust and efficiency would have also boosted the payload numbers.

Studies were done with various upper stages, showing about 30% improvement.  For example,the Int-20 Saturn, put a SIVB (third stage for the Saturn V) on top of the S-ID first stage. This could launch 180,000 lb (81,600 kg)  into orbit, an increase of 48,000 lb (21,800 kg) over the standard S-1C stage version.  The first version of the SLS is supposed to put 70 tons in orbit, this version of the Int-20 beats that.

The S-ID would have been operational in 1972, probably would have been used in the third order of Saturn Vs.  But in 1968, budgets were already being cut.  The second run of Saturn Vs was canceled before Apollo 11 landed on the moon.  Plans for enhanced Saturn Vs, space stations, and moonbases were not to be.  The saturn rockets were scrapped in favor of the space shuttle which promised cheaper flights and reuse.

The S-1D would have weighed 5,099,000 lb (2,300,000 kg) at takeoff.

The Reusable Station aka the Space Shuttle

   Every time the shuttle flew, NASA had a space station in orbit. 

   
   Space stations have been conceived since before human spaceflight.  Designs for outposts, research bases, work platforms, service bays,  and launch platforms were proposed.  The shuttle was able to perform all of these functions and more.  Its major shortcoming as a space station was its limited endurance on orbit.

   All manned spacecraft before the shuttle were capsules with limited volume and equipment for the crew. They were limited to crews of 3 or less that were smaller inside than most compact cars.  Capsules transported crews to space and back.  There was little room for anything else.

   On board the shuttle, things were different. The crew had a two deck cabin with a flight seats, work stations, a galley, sleeping quarters, storage, a hygiene station, and even a toilet. Up to 7 astronauts could spend up to 17 days in relative comfort.

  The shuttle was like a space station, it had an airlock, a remote manipulator arm, cargo bay lights, and other equipment needed for operations in orbit.  Each flight was outfitted for the mission objectives.

   Space lab and Space Hab modules could be carried increasing habitable volume and space for experiments.

   Power was provided by three fuel cells.  It was the fuel cells that limited the shuttles time in orbit. Large solar arrays were studied under a number of different projects.   NASA eventually used extra cryogenic tanks in the payload bay, and finally reversing the power flow while docked at the ISS to extend the time on orbit.
 
  Many ideas that were conceived for use on a space station were tried and used on the shuttle. Thirty years of experiments in life sciences, materials, astronomy, space construction techniques, space walks, earth observations, physics, and microgravity research would have been an astounding success for 5 space stations. With the science and work they accomplished, they compare well to the Soviet Salyut and Mir stations.
  One of my favorite memories is of the first flights of the manned maneuvering unit (MMU).  It was like Buck Rodgers, astronauts could fly in space untethered.  Many space station concepts had thought of something like the MMU, but it flew on the shuttle.  At the time it seemed that the shuttle was living up to expectations.  The future of space flight looked bright, the sky was the limit.  But that's another blog post.

   The large 15' x 60' cargo bay could serve as a work platform, service and repair bay, experiment platform, and launch platform.  During its career, the shuttle deployed 99 spacecraft.  Three of NASA's great observatories, the Hubble Space Telescope(1990), the Compton Gamma Ray Observatory(1990), and the Chandra X-ray Observatory(1999) were deployed  from the payload bay.  On 5 occasions, the Hubble Space Telescope was serviced, replacing gyroscopes, solar panels, instruments, and returned to continue deepening our view of the cosmos.  Intelsat VI, Solar Max, Leasat-F3, were repaired on orbit and  put back in operation.  Several deep space probes including Galileo, Magellan, Ulysses, started their journeys aboard the shuttle.
 

   Special payloads using the shuttles unique capabilities were flown.  The Wake Shield facility conducted experiments in ultra vacuum on three flights.  The space tether experiment flew twice.  The Long Duration Exposure Facility (LDEF) was deployed in 1984 by Challenger, and retrieved by Columbia in 1990 several years later than planned, testing many materials in the space environment.  The 13' x 102' OAST1 solar array was deployed several times  by Discovery in 1984 testing several different kinds of light weight solar cells.  The Experimental Assembly of Structures in EVA and the Assembly Concept for Construction of Erectable Space Structures, or EASE/ACCESS, were a pair of experiments that tested space construction techniques on Atlantis in 1985.  The European Retrievable Carrier (EURECA) was deployed by Atlantis in 1992, and retrieved by Endeavor in 1993.  Japans Space Flyer Unit launched in 1995 by a H2 rocket was returned to Earth by Endeavor in 1996.

  Department of Defense and National Reconnaissance Office requirements were the reason for the large payload bay.  Otherwise the shuttle would have been much smaller.  11 dedicated DOD missions were flown deploying classified payloads.  Speculations about these missions include the Lacrosse Radar Imaging Satelite, various DOD sats, Magnum elint sats, as well as Misty, a supposed stealthy spy sat.  Other payloads were tested in orbit by the military.  The air forces X-37 was also designed to fit in the payload bay.   Eventually all astronauts who flew on DOD missions were awarded National Intelligence Achievment medals.  In many ways, the shuttle surpassed the air forces aborted Manned Orbiting Laboratory space station.

   Even before Columbia first flew, construction of a station was seen as one of its purposes and destinations. Construction of the ISS was probably the shuttle programs greatest achievement and legacy.  During the early phases of construction of the ISS, power was drawn from the docked shuttle.  Serving as a construction  platform, components were launched, delivered, and installed.  Sadly the shuttle fleet was retired when the station was completed but their time had come.

  The shuttle almost became the ISS, during the redesign in the early 90's.  Option C proposed to develop the Shuttle-C as a space station.  I would have preferred this one over the Option A ISS  that was built.  It would have provided more habitable volume like skylab.  The station would have been operational after launch and fewer flights would have been needed to finish outfitting the station.  And NASA would have acquired a heavy lift launch vehicle, something they have been trying to do since retiring the Saturn V.  

Now the shuttle has been retired, gone the way of the saturns before.   In twenty years, I wonder if we will remorse the loss of the shuttles the same as the loss of the saturn rockets.

  

The Saturn Rockets, what was and what might have been

Almost everyone has heard of the Saturn V, the Rocket that sent men to the moon.  It was and still is the largest, most powerful booster ever flown.  Over forty years ago, the american space program was able to design, build, and fly this monster in less than a decade.   The Saturn V development, done at a time when much still needed to be learned about launch systems, took only 4 years to complete (Contract awarded in 1962, first flight in 1966.)