Launcher Option 2: Space Shuttle and Titan

Using one Space Shuttle launch and a Titan IV cuts the cost of launch, and still uses solely American launchers. It saves $100 M from one of the launches, as the Titan IV is (only) $300 M. The Titan IV also has a slightly larger payload shroud than the Space Shuttle, which is very useful when handling low-density cryogenic hydrogen. Also, the Titan is able to carry cryogenics, which is a hole in the all-Shuttle plan.

At a total cost of at least $700 M, this is still a very expensive launch setup. Having one of the launchers not man-rated (the Titan has mediocre reliability) reduces the flexibility of launching the crew. The lack of a second mission with a Remote Manipulator System, and the flexibility of a flight crew present adds to mission risk and detracts more from flexibility.

The Titan IV has a lower payload capacity than the Space Shuttle, and we will in all likelihood need another small launch, or sacrifice significant mission objectives. A Titan III is another $100 M, and has a capacity of 26,000 lbs (12,000 kg).

The Titan IV has a payload of about 48,000 lbs (22,000 kg), and the Space Shuttle, 55,000 lbs (25,000 kg) [which may be upgraded to about 62,000 lbs (28,000 kg)]. This gives a total capacity of 103,000 - 110,000 lbs (47,000 - 50,000 kg). This is just borderline feasible for the manned mission in terms of payload capacity, and it is likely another small launch would have to be booked. For another $100 M, a Titan III could be bought, which would bring total payload capacity up to a nice 129,000 - 136,000 lbs (59,000 - 62,000 kg), but for a whopping $800 M.

Launcher	Payload	Cost
Shuttle + Titan IV	103,000 lbs (47,000 kg)	$700 M
Shuttle (upgrade) + Titan IV	110,000 lbs (50,000 kg)	$700 M
Shuttle + Titan IV + Titan III	129,000 lbs (59,000 kg)	$800 M
Shuttle (upgrade) + Titan IV + Titan III	136,000 lbs (62,000 kg)	$800 M

Although it has a higher payload than the two Shuttles option, it lacks a second man-rated launch and adds the complexity of a second rendezvous, and it is no cheaper, so this is an unlikely scenario.