Space Station Options 1993

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Space Station Options 1993

Space Station C4 - Space Station Option C4.

Credit: NASA via Marcus Lindroos. 15,790 bytes. 187 x 480 pixels.

Nation: USA. Agency: NASA.

Following the collapse of Space Station Fred, NASA quickly formed a Space Station redesign team which identified three major redesign options in April 1993....

These were:

Option B, the most expensive design, was very similar to the 1991 'Fred' design. Option B would have omitted one truss segment while simplifying some subsystems to save money. The Station assembly schedule would also have been delayed, and the project management structure would have been overhauled as well.. The total cost over five years could not be kept to under $9 billion, however, and this effectively killed the concept, although Space Station Freedom supporters in Congress preferred this option. Compared with Space Station Freedom, Option B would have saved some money by starting with half of the original design and grow to full size as the budget allowed. Like Option A, Option B would initially have relied on a docked Shuttle to provide housing for the crew. However, 'just going up for [less than 20] days and coming back...is nothing but Shuttle plus. It wouldn't be worth the money to do that' according to the Advisory Panel's Daniel Hastings. The completed Option B station would have offered better on-board data storage and lab space than Option A, but would also have required an additional 10 assembly flights and 60 hours of external assembly and maintenance work by astronauts. The technical risk was regarded as lower than for the other two Options, but the design still wasn't detailed enough for an accurate assessment of its user capabilities to be made.

Option C was the most controversial alternative since it represented a radical departure from all previous Space Station plans. It featured a single large 28m long, 7m diameter pressurised 'can' that would be launched fully outfitted on a new Shuttle derived heavy-lift booster. The cost of the core module was estimated to be $3.19 billion; a total cost of $6.502 billion over five years excluding reserves, operations and the $1 billion Freedom termination cost. The Shuttle, ESA Columbus and Japanese Experiment Modules would all be docked to the Option C Space Station. This design would have given researchers more lab space and power than Freedom, and it could support a permanent crew from the start while requiring less external maintenance by astronauts.

It would have included no fewer than 136 experiment racks - nearly three time as many as 'Fred' and far more than the Option C solar arrays could support. But its microgravity environment was comparatively poor since the Station would have to rotate to keep its solar panels facing the Sun or else the power would vary. The design made adding more solar panels very difficult. The Europeans, Japanese and Canadians disliked this option since would have to change the electrical, thermal control and data management systems of their modules - if they could be accommodated at all. The international contributions would also be rendered largely useless (e.g. Canada's robotic arm would also be of little value since little on-orbit assembly would required).

The Option C Space Station would have been launched in one piece on a new unmanned Shuttle-derived heavy-lift rocket. The design was regarded as a very high-risk venture since the Station would have to be developed essentially from scratch and tested in a very short time, and it would rely on a new launch vehicle that would have to work on its maiden voyage (NASA was going to use cannibalised parts from the Shuttle Orbiter 'Columbia' to save money). Nonetheless, the 'blue ribbon' selection panel endorsed Option C along with Option A. NASA proposed to farm out the construction of the 'can' to Russia in order to save money. The Russians declined, however, since they felt the bid wasn't detailed enough.

Station Option A '93

Credit: NASA via Marcus Lindroos. 18,152 bytes. 542 x 480 pixels.

Option A was the 'compromise option' eventually chosen by Clinton. Like Option B, this configuration was based on the abandoned Space Station Freedom design from 1991, so it was more acceptable to the international partners than Option C. Option A would start with a 'power station' to which an extended duration Shuttle could dock for initial research lasting 20 days at most. Lockheed's 'Bus-1' (a previously classified US Air Force spacecraft) would provide propulsion and attitude control. The US laboratory and node would also be integrated into a single module.

Station Option A '93

Credit: NASA via Marcus Lindroos. 14,258 bytes. 636 x 430 pixels.

Later, additional laboratories and a habitation module could be added to create the complete Option A Space Station shown here. A major drawback was the limited capability for scientific research, particularly for sensitive microgravity experiments since the Station periodically (every 2-3 months) would have to reorient itself 90 degrees to keep solar panels pointing toward the Sun. This would interrupt materials science regularly. Consequently, the Clinton Administration promised to use the same 'alpha' solar panel joints as Option B. The total estimated cost in 1994-98 was $13.3 billion, considerably higher than the $9-billion Space Station requested by the President in March 1993. NASA was asked to report back in September 1993 since the current Option A design was not detailed enough for an accurate assessment of its user capabilities to be made.



1993 SPACE STATION OPTIONS SUMMARY
-------------------------------------------------------------------
COSTS
($ billions)         Freedom  A/Bus-1  Option-B  Option-C  R-Alpha
-------------------------------------------------------------------
-FY 1994-98          $15.8    $13.3    $13.3     $11.9     $10.5
-FY'94 to
 assembly complete   $22.1    $17.0    $19.3     $15.2     $19.4
-Ops. & payloads     $25.0    $13.5    $15.1     $10.2        ?
-Total lifetime cost 
 incl.marginal STS   $65      $47      $50       $41
 flight cost
-Total lifetime cost $101     $80      $87       $65
 incl.average STS
 flight cost

-------------------------------------------------------------------
MILESTONES           Freedom  A/Bus-1  Option-B  Option-C  R-Alpha
-------------------------------------------------------------------
-1st element launch     3/96    10/97     10/97      9/99     6/97
-Man-tended capacity    6/97     4/98     12/98       -       8/97
-International modules 12/99    12/99      3/01      7/00     4/00
-Permanent crew         6/00     9/00     12/01     11/99     9/97
-Assembly complete      9/00     9/00     12/01      1/01    10/01


-------------------------------------------------------------------
PERFORMANCE          Freedom  A/Bus-1  Option-B  Option-C  R-Alpha
-------------------------------------------------------------------
Orbit inclination       28.5     28.5      28.5      28.5     51.6
Crew research hr/yr     6866h    6724h     6566h     6866h
Total power (kW)        68.3       57      68.3      61.5      105
User power (kW)         34.2       31      40.3      40.9     < 45     
Habitable volume (m3)    878      760       878      1117     1200
Equipment racks
  system racks            65       59        65      50.5       51* 
  user racks              45.5     39        45.5      72       33*
  user racks @ <1uG       29        8        29        40        ?
Assembly EVA, h.         340h     224h      311h       24h    224h
Annual maintenance EVA   240h     187h      253h       80h    197h
Total assembly flights    20       16        20        10   14+12 Russian.
Logistics fligths/yr.      4        6         6         6        7


* = does not include Russian equipment racks.

Station Option A-Rus

Credit: NASA via Marcus Lindroos. 17,675 bytes. 634 x 432 pixels.

Article by Marcus Lindroos

Specification

Electrical System: Solar panels.

Station Option A-Rus

Credit: NASA via Marcus Lindroos. 16,382 bytes. 801 x 600 pixels.

Station Option B '93 - Compared with Space Station Freedom, Option B would have saved some money by starting with half of the original design and grow to full size as the budget permits.

Credit: NASA via Marcus Lindroos. 20,624 bytes. 629 x 471 pixels.

Space Station C3 - Space Station Option C3. Option C was the most controversial alternative since it represented a radical departure from all previous Space Station plans. It featured a single large 28m long, 7m diameter pressurized "can" that would be launched fully outfitted on a new Shuttle derived heavy-lift booster.

Credit: NASA via Marcus Lindroos. 46,650 bytes. 640 x 457 pixels.

Station Option C '93 - The Option C Space Station would have been launched in one piece on a new unmanned Shuttle-derived heavy-lift rocket.

Credit: NASA via Marcus Lindroos. 7,998 bytes. 638 x 314 pixels.

Station Option C '93

Credit: NASA via Marcus Lindroos. 12,496 bytes. 636 x 451 pixels.

Station Option C '93

Credit: NASA via Marcus Lindroos. 9,992 bytes. 636 x 326 pixels.

Space Station C5 - Space Station Option C5

Credit: NASA via Marcus Lindroos. 18,905 bytes. 186 x 480 pixels.

Space Station C6 - Space Station Option C6. This illustration show the Shuttle, ESA Columbus and Japanese Experiment Modules docked to the Option C Space Station.

Credit: NASA via Marcus Lindroos. 43,863 bytes. 612 x 480 pixels.

Space Station Fred - The most expensive "Option B" design was very similar to the 1991 "Fred" design shown here. Option B would have omitted one truss segment while simplifying some subsystems to save money.

Credit: NASA via Marcus Lindroos. 58,223 bytes. 640 x 432 pixels.

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Last update 12 March 2001.
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