tag:blogger.com,1999:blog-2675974463524895416.post6662696679614365279..comments2024-03-28T10:26:00.255-05:00Comments on An Ex Rocket Man's Take On It: Access to Space: Commercial vs Government RocketsGary Johnsonhttp://www.blogger.com/profile/06723964751681093047noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-2675974463524895416.post-44506346452592274912015-08-08T20:07:08.606-05:002015-08-08T20:07:08.606-05:00Appreciate your comment Gary!
I wasn't attemp...Appreciate your comment Gary!<br /><br />I wasn't attempting to imply that the SLS was the only game in town. I just said that the SLS will be able to do some things that smaller rocket vehicles with much smaller fairing sizes simply could not do. <br /><br />8.4 meter in diameter habitat modules makes it a lot easier to internally mass shield inhabited sections with water for interplanetary journeys. This would be much more mass efficient than attempting to externally shield an entire habitat module. <br /><br /> And for long multi-month interplanetary journeys, I think 8.4 meter in diameter habitat modules should make it much more physically and psychologically comfortable for astronauts. <br /><br />Similar 8.4 meter in diameter habitats deployed to the surface of the Moon and Mars could be externally mass shielded with regolith, allowing astronauts to live in habitats as spacious as multilevel homes on Earth. <br /><br />Marcel <br /><br /><br />Marcel F. Williamshttps://www.blogger.com/profile/16245086958213100840noreply@blogger.comtag:blogger.com,1999:blog-2675974463524895416.post-63793261831906379542015-08-08T13:48:49.250-05:002015-08-08T13:48:49.250-05:00Hi Marcel:
You're right for the near term abo...Hi Marcel:<br /><br />You're right for the near term about SLS being the only game in town for big stuff. Longer term (a few to several years from now), I think Musk's MCT might do an even better job a lot cheaper. <br /><br />I also think that we won't need as many 8 to 10 m diameter payloads as a lot of folks contend. Not if we get off dead center and start doing real assembly and construction work in LEO. <br /><br />Which requires a supple spacesuit, among other things. And MCP is the way to achieve it. <br /><br />-- GWGary Johnsonhttps://www.blogger.com/profile/06723964751681093047noreply@blogger.comtag:blogger.com,1999:blog-2675974463524895416.post-37502163126782798202015-08-07T19:48:18.709-05:002015-08-07T19:48:18.709-05:00The SLS will provide two things that no other laun...The SLS will provide two things that no other launch vehicles will be capable of.<br /><br />When fully operational, it should be able to deploy at least 95 tonnes to LEO with an upper stage (essential for beyond LEO missions). No other vehicle, not even the Falcon Heavy, will come close to this. <br /><br />Secondly, the SLS will be able to accommodate large payloads within a fairing diameter that could range from 8.4 meters to 10 meters in diameter. No private launch vehicle will have a payload fairing larger than 6 meters in diameter. <br /><br />So the SLS will be the only vehicle capable of deploying Bigelow's largest payload concept, the BA-2100. Bigelow Aerospace has already asked NASA about launching its largest space habitat concept. <br /><br /> The SLS will also be the only vehicle capable of deploying uber-lite 8.4 meter in diameter Deep Space Habitats directly derived from repurposed SLS propellant tanks that could have internal volumes exceeding that of the ISS (the Skylab II concept). <br /><br />A large payload fairing may also be essential for deploying large ADEPT decelerators for deploying crewed vehicles and large cargoes (20 tonnes plus) to the Martian surface. <br /><br />The annual cost of being able to launch Space Shuttle has been estimated at nearly $1.875 billion a year (in 1994 dollars)-- without launching a single Shuttle flight. The additional cost per Shuttle launch has been estimated at approximately $125 million (19994). In today's dollars that would be approximately $3 billion with $200 million added for each launch. <br /><br />So one Shuttle launch per year, in today's dollars, would have cost NASA $3.2 billion. Five launches would have cost them $4 billion, $800 million per launch. <br /><br />NASA estimated that the Sidemount Shuttle cost for five launches would be about $500 million (much lower than the Space Shuttle) and estimated that an SLS type of vehicle would cost about 10% more than the Sidemount Shuttle ($550 million) per launch. <br /><br />Even though these launch cost don't include the cost of payloads, spending less than $3 or $ 4 billion a year for five heavy lift launches doesn't seem to be excessively costly within NASA's ~$8 billion a year human spaceflight related budget-- to do things that no other vehicles can!<br /><br /><br />Marcel <br /><br /><br /><br />Marcel F. Williamshttps://www.blogger.com/profile/16245086958213100840noreply@blogger.com