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	<title>Selenian Boondocks &#187; MSS</title>
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	<link>http://selenianboondocks.com</link>
	<description>Random Musings from the Warped Minds of Jonathan Goff, Ken Murphy, John Hare, and Kirk Sorensen</description>
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		<title>Transitions</title>
		<link>http://selenianboondocks.com/2010/09/transitions/</link>
		<comments>http://selenianboondocks.com/2010/09/transitions/#comments</comments>
		<pubDate>Sat, 11 Sep 2010 07:15:34 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[Administrivia]]></category>
		<category><![CDATA[Altius Space Machines]]></category>
		<category><![CDATA[MSS]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=1676</guid>
		<description><![CDATA[While some of you may have known for a while, I think that Clark may have surprised a lot of readers when he pointed out the news that I was no longer a part of the Masten team. I am proud to have been one of the founding members of their team, and I still [...]]]></description>
			<content:encoded><![CDATA[<p>While some of you may have known for a while, I think that Clark may have surprised a lot of readers when he <a href="http://hobbyspace.com/nucleus/index.php?itemid=23449">pointed out the news</a> that I was no longer a part of the Masten team. I am proud to have been one of the founding members of their team, and I still think that their vision and approach for suborbital RLV development is an excellent one.  But I started realizing earlier this year that my interests and vision had diverged enough from theirs that I really needed to start-off on my own.  So, back in early July, I left Masten to start my own company, <a href="http://www.altius-space.com">Altius Space Machines</a>.</p>
<p>Before I leave the topic, and for what it&#8217;s worth, I recently got to spend two weeks training my replacement there at Masten, Alex Hreiz, and have to say that I think the Masten 3.0 team has a lot of potential.  I am also really excited about <a href="http://masten-space.com/blog/?p=549">the CRuSR award they won</a>, and hope they and Armadillo can both do the industry proud in executing on those contracts.</p>
<p>For those who are curious, I&#8217;ll give some more details in the future about what I&#8217;m trying to accomplish with Altius Space Machines.  But right now I&#8217;ve been incredibly busy trying to put together proposals for and carry out some initial contract work, pull together my core team, get all of the boring details of starting a company taken care of properly, and work out all the details of setting up shop in another state.  Add on top of that all the family challenges associated with the passing of Tiffany&#8217;s mother due to cancer last month, the marriage of her youngest brother yesterday, and packing up a house for the eventual move out to Colorado, and you get an idea of why blogging has and will continue to be light.</p>
<p>While all of this has been extremely exhausting, the last several months have also been very personally fulfilling.  I&#8217;m really excited about the coming months, both for Altius and Masten.  Altius has a long way to go, and a lot of hard work ahead of us, but I&#8217;m really excited for our vision, and by the challenge of making that vision a reality.</p>
<p>I&#8217;ll keep you guys posted as I get the opportunity.</p>
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		<title>Masten and XCOR NASA Lander Strategic Relationship</title>
		<link>http://selenianboondocks.com/2010/05/masten-and-xcor-nasa-lander-strategic-relationship/</link>
		<comments>http://selenianboondocks.com/2010/05/masten-and-xcor-nasa-lander-strategic-relationship/#comments</comments>
		<pubDate>Tue, 25 May 2010 17:03:48 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[Commercial Space]]></category>
		<category><![CDATA[Lunar Commerce]]></category>
		<category><![CDATA[Lunar Exploration and Development]]></category>
		<category><![CDATA[MSS]]></category>
		<category><![CDATA[NASA]]></category>
		<category><![CDATA[Space Transportation]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=1583</guid>
		<description><![CDATA[I had to keep this under wraps until this morning, but it&#8217;s now formal: May 25th, 2010, Mojave, CA, USA: XCOR Aerospace and Masten Space Systems, two of the leaders in the New Space sector, have announced a strategic business and technology relationship to pursue jointly the anticipated NASA sponsored unmanned lander projects. These automated [...]]]></description>
			<content:encoded><![CDATA[<p>I had to keep this under wraps until this morning, but it&#8217;s <a href="http://masten-space.com/blog/?p=529">now formal</a>:</p>
<blockquote><p>May 25th, 2010, Mojave, CA, USA: XCOR Aerospace and Masten Space Systems, two of the leaders in the New Space sector, have announced a strategic business and technology relationship to pursue jointly the anticipated NASA sponsored unmanned lander projects. These automated lander programs are expected to serve as robotic test beds on Earth, on the lunar surface, Mars, near Earth objects and other interplanetary locales, helping NASA push the boundaries of technology and opening the solar system for future human exploration.</p>
<p>Masten’s award winning automated vertical take off, vertical landing (VTVL) flight vehicles combined with XCOR’s strong experience in liquid oxygen (LOX) / methane powered propulsion systems and nonflammable cryogenically compatible composite tanks, brings to NASA a powerful and competitive combination of innovative talent with a proven record of producing exceptional results quickly and affordably.</p>
<p>Last October, Masten won the $1 million first prize for Level II of NASA’s Lunar Lander Challenge, beating out a host of New Space rivals, and demonstrating they are the leading VTVL development group in the country. In 2007 XCOR Aerospace’s LOX/methane engine, developed for NASA, was named by Time Magazine as one of the “Inventions of the Year”, recognizing XCOR’s successive advancement in the state of the art of both pump and pressure fed reusable, throttle-able rocket propulsion systems. XCOR and Masten have also demonstrated the ability to rapidly take from concept to live fire, new propulsion and control system designs using innovative rapid prototyping techniques that surpass client requirements in much shorter periods of time than traditional aerospace methods.</p>
<p>Dave Masten, founder and President of Masten Space Systems commented “Masten Space and XCOR are next door neighbors here in Mojave. We’ve worked together on many tactical problems over the years and our corporate cultures mesh well. Working together on something like this simply made too much sense. We can’t wait to start working with Jeff, Dan, and the XCOR team to help NASA build affordable and responsive landing platforms.”</p>
<p>“Our company work ethic and styles are very compatible, and with XCOR propulsion and Masten VTVL technology, we can solve problems of national interest, and I am excited about the possibilities,” said Jeff Greason, CEO and Founder of XCOR.<br />
Andrew Nelson, Chief Operating Officer of XCOR added, “It’s a no brainer, Dave’s team is the absolute best New Space company when it comes to VTVL and autopilot unmanned operations – they demonstrated that in October by winning NASA’s lander challenge. And we feel our LOX/methane engines are unsurpassed in the trade space today by anyone. We should bring this tandem set of best in class capabilities to NASA, it just makes sense for them and for us.”</p>
<p>XCOR and Masten will be jointly marketing their skill sets and services to the NASA community as prime contractors, and as joint teaming partners for larger systems integrators and prime contractors servicing the NASA community.</p>
<p># # # # #</p>
<p>Masten Space Systems is a Mojave, CA based aerospace company developing fully reusable vertical takeoff, vertical landing (VTVL) launch vehicles, rocket-related products, and engineering services. The company’s 6000 square foot production facility and 200,000 square foot testing facility is located on the Mojave Air and Space Port. The company designs and builds aerospace solutions that focus on durability, long operational lifetimes, and minimal per-flight maintenance. For more information on the company see http://masten-space.com</p>
<p>XCOR Aerospace is a California corporation located in Mojave, California. The company is in the business of developing and producing safe, reliable and reusable rocket powered vehicles, propulsion systems, advanced non-flammable composites and other enabling technologies for responsive private space flight, scientific missions, upper atmospheric research, and small satellite launch to low earth orbit. The Lynx is a piloted, two seat, fully reusable, liquid rocket powered vehicle that takes off and lands horizontally. The Lynx production models (designated Lynx Mark II) are designed to be robust, multi-commercial mission vehicles capable of flying to 100+ km in altitude up to four times per day. XCOR’s web address is: www.xcor.com.</p>
<p>Contact:<br />
Michael Mealling<br />
Masten Space Systems<br />
Phone: +1-888-488-8455 x102<br />
Email: mmealling@masten-space.com</p>
<p>Mike Massee<br />
XCOR Aerospace<br />
Phone +1-661-824-4714 x127<br />
Email: press@xcor.com</p></blockquote>
<p>I can&#8217;t speak for the company, but personally I&#8217;m really glad we were able to find a way to make this partnership work.  I&#8217;ve got nothing but respect for the XCOR team, and have been trying to find a way to work with them for years.  As Jeff said at Space Access, it&#8217;s deals like this that show that the industry is starting to grow up.</p>
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		<title>Xoie in the Wind</title>
		<link>http://selenianboondocks.com/2010/01/xoie-in-the-wind/</link>
		<comments>http://selenianboondocks.com/2010/01/xoie-in-the-wind/#comments</comments>
		<pubDate>Tue, 19 Jan 2010 00:49:09 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[MSS]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=1359</guid>
		<description><![CDATA[Here&#8217;s an old video from our 195s tethered flight the day before our NGLLC Level 2 competition slot.  Winds gusting past 30 knots, and it&#8217;s still rock solid.  If you count tethered flights, I think it&#8217;s the longest duration VTVL flight ever (longer than DC-X or Armadillo): It just goes to show that while every [...]]]></description>
			<content:encoded><![CDATA[<p>Here&#8217;s an old video from our 195s tethered flight the day before our NGLLC Level 2 competition slot.  Winds gusting past 30 knots, and it&#8217;s still rock solid.  If you count tethered flights, I think it&#8217;s the longest duration VTVL flight ever (longer than DC-X or Armadillo):</p>
<p><center><object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" width="560" height="340" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0"><param name="allowFullScreen" value="true" /><param name="allowscriptaccess" value="always" /><param name="src" value="http://www.youtube.com/v/AIMY5Qx37oA&amp;hl=en_US&amp;fs=1&amp;" /><param name="allowfullscreen" value="true" /><embed type="application/x-shockwave-flash" width="480" height="291" src="http://www.youtube.com/v/AIMY5Qx37oA&amp;hl=en_US&amp;fs=1&amp;" allowscriptaccess="always" allowfullscreen="true"></embed></object></center></p>
<p>It just goes to show that while every landing for a VTVL vehicle is a crosswind landing, that&#8217;s not necessarily a showstopper.</p>
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		<slash:comments>9</slash:comments>
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		<item>
		<title>Latest Masten Update</title>
		<link>http://selenianboondocks.com/2009/12/latest-masten-update/</link>
		<comments>http://selenianboondocks.com/2009/12/latest-masten-update/#comments</comments>
		<pubDate>Thu, 31 Dec 2009 07:27:34 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[Administrivia]]></category>
		<category><![CDATA[MSS]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=1347</guid>
		<description><![CDATA[Dave just wrote the latest Masten Update over on our MSS Project Blog.  The update goes over some of our plans for the new year.  Hopefully I&#8217;ll have something more to talk about soon.]]></description>
			<content:encoded><![CDATA[<p>Dave just wrote the latest <a href="http://masten-space.com/blog/?p=502">Masten Update</a> over on our <a href="http://masten-space.com/blog/">MSS Project Blog</a>.  The update goes over some of our plans for the new year.  Hopefully I&#8217;ll have something more to talk about soon.</p>
]]></content:encoded>
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		<slash:comments>0</slash:comments>
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		<item>
		<title>Space 2009 Papers</title>
		<link>http://selenianboondocks.com/2009/09/space-2009-papers/</link>
		<comments>http://selenianboondocks.com/2009/09/space-2009-papers/#comments</comments>
		<pubDate>Sun, 20 Sep 2009 06:34:50 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[MSS]]></category>
		<category><![CDATA[Propellant Depots]]></category>
		<category><![CDATA[Technology]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=1187</guid>
		<description><![CDATA[I only have a few minutes tonight, but part of what&#8217;s been keeping me busy lately has been two Space 2009 papers I&#8217;ve been involved with (one as the primary author, and another as a very minor coauthor). First, the propellant depot paper I keep talking about: AIAA 2009-6756 Near-Term Propellant Depots: Implementation of a [...]]]></description>
			<content:encoded><![CDATA[<p>I only have a few minutes tonight, but part of what&#8217;s been keeping me busy lately has been two Space 2009 papers I&#8217;ve been involved with (one as the primary author, and another as a very minor coauthor).</p>
<p>First, the propellant depot paper I keep talking about: <a href="http://selenianboondocks.com/wp-content/uploads/2009/09/NearTermPropellantDepots.pdf">AIAA 2009-6756 Near-Term Propellant Depots: Implementation of a Critical Spacefaring Technology</a> (also available on the <a href="http://www.ulalaunch.com/index_published.html">ULA publications page</a>), and the presentation that went along with it: <a href="http://selenianboondocks.com/wp-content/uploads/2009/09/SPACE2009PropDepotPaper.ppt">SPACE 2009 Prop Depot Paper Presentation</a>.</p>
<p>For those who&#8217;ve read most of the rest of my posts on propellant depots, there&#8217;s only a few key new concepts:</p>
<ul>
<li> The Single-Launch Dual-Fluid Depot concept that Frank Zegler and myself both independently came up with this year (which I&#8217;ll go into more in a later blog post).   This idea holds a lot of promise because it shows how a single EELV launch with existing fairing sizes can put up a depot capable of storing 75-114mT of LOX/LH2.</li>
<li>The realization that unless you have some sort of high-Isp or propellantless propulsion system (like an ED tether) for stationkeeping purposes, that Zero-Boiloff storage might not be very useful for an LEO depot.  The amount of propellant you lose to boiloff is less than the amount you would&#8217;ve spent for stationkeeping anyway, so it&#8217;s effectively free.</li>
<li>The realization that LEO depots really ought to be treated as &#8220;use-it-or-lose-it&#8221;, high-throughput depots, and that its L1/L2 depots that should be used for longer-term storage.</li>
</ul>
<p>I had been avoiding discussion of the dual-fluid depot concept for a while, mostly so I wouldn&#8217;t be stealing my own thunder.  Now that the paper is presented and out in the public, I hope to have the time soon to discuss the concept a bit.  I also have some space transportation architecture ideas using that depot concept that I may flesh out a bit either here on the blog or in some white papers (which I&#8217;ll post on the blog).</p>
<p>The second paper, which was mostly written by Robert Frampton of Boeing talks about a project to use our XA-0.2 vehicle as a testbed for demonstrating autonomous landing systems for planetary landers: <a href="http://selenianboondocks.com/wp-content/uploads/2009/09/Boeing_AIAA-2009-6571.pdf">AIAA-2009-6571 Planetary Lander Dynamic Model for GN&amp;C</a></p>
<p>I&#8217;m not really sure what I&#8217;m allowed to say about the project that isn&#8217;t spelled-out in the paper, but I figured I&#8217;d bring it to people&#8217;s attention, and hopefully at some point in the future I can discuss things more on the <a href="http://masten-space.com/blog">MSS blog</a>.</p>
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		<title>Light Blogging: The Continuing Excuses Continue&#8230;</title>
		<link>http://selenianboondocks.com/2009/08/light-blogging-the-continuing-excuses-continue/</link>
		<comments>http://selenianboondocks.com/2009/08/light-blogging-the-continuing-excuses-continue/#comments</comments>
		<pubDate>Tue, 25 Aug 2009 19:04:47 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[Administrivia]]></category>
		<category><![CDATA[MSS]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/2009/08/light-blogging-the-continuing-excuses-continue/</guid>
		<description><![CDATA[So, I got my big propellant depot paper done in time, but now I have some other stuff that will probably keep me from posting much for a while: http://thelaunchpad.xprize.org/2009/08/2009-ngllc-first-attempts.html]]></description>
			<content:encoded><![CDATA[<p>So, I got my big propellant depot paper done in time, but now I have some other stuff that will probably keep me from posting much for a while:</p>
<p><a href="http://thelaunchpad.xprize.org/2009/08/2009-ngllc-first-attempts.html">http://thelaunchpad.xprize.org/2009/08/2009-ngllc-first-attempts.html</a></p>
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		<slash:comments>4</slash:comments>
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		<item>
		<title>Random Thoughts: Pre-Depot 2-Launch Manned Missions Using L2 Swingby</title>
		<link>http://selenianboondocks.com/2009/06/random-thoughts-pre-depot-2-launch-manned-missions-using-l2-swingby/</link>
		<comments>http://selenianboondocks.com/2009/06/random-thoughts-pre-depot-2-launch-manned-missions-using-l2-swingby/#comments</comments>
		<pubDate>Sun, 28 Jun 2009 08:45:53 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[Bigelow Aerospace]]></category>
		<category><![CDATA[Commercial Space]]></category>
		<category><![CDATA[ESAS]]></category>
		<category><![CDATA[Launch Vehicles]]></category>
		<category><![CDATA[Lunar Commerce]]></category>
		<category><![CDATA[Lunar Exploration and Development]]></category>
		<category><![CDATA[MSS]]></category>
		<category><![CDATA[NASA]]></category>
		<category><![CDATA[Propellant Depots]]></category>
		<category><![CDATA[Space Transportation]]></category>
		<category><![CDATA[SpaceX]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=1076</guid>
		<description><![CDATA[Ok, two weeks ago, I mentioned that the &#8220;pre-depot&#8221; dual EELV launch concept my friend had passed to me could be adapted to do manned lunar missions.  Lunar missions are a lot easier to close if you assume a depot in LEO (and even easier if there&#8217;s also a small depot at L2).  But it [...]]]></description>
			<content:encoded><![CDATA[<p>Ok, two weeks ago, I mentioned that the &#8220;pre-depot&#8221; dual EELV launch concept my friend had passed to me could be adapted to do manned lunar missions.  Lunar missions are a lot easier to close if you assume a depot in LEO (and even easier if there&#8217;s also a small depot at L2).  But it turns out that if you use a couple of tricks, you can actually make a pre-depot concept close as well.  This wouldn&#8217;t be my optimal approach, but it at least illustrates the point.</p>
<p>The mission uses the following tricks to make things work:</p>
<ul>
<li>Dual Engine Centaur for this mission is stretched by 50% and includes an &#8220;Extended Mission Kit&#8221; to allow for it to function for the ~5 days necessary for the mission (normal DEC dry mass is ~5400lb, and the EMK is ~1750lb and includes stuff like extra hydrazine bottles, more batteries, deep space navigation upgrades to avionics, sunshields, etc)</li>
<li>Command module does a powered lunar swingby to go to L2, thus cutting down on overall dV requirements (~750m/s total required, 335m/s per leg), thus allowing for a much smaller CSM (possibly with the service module integrated into the command module).</li>
<li>The Stretched Centaur and the Lander break into lunar orbit and descend to the surface instead of continuing to L2.  I&#8217;m not positive if this allows you to land anywhere on the lunar surface or not (this is one of the few big questions for this mission mode).  This avoids the extra dV requirements you normally get for stopping everything at L2 first.</li>
<li>Upper stage performs part of the landing burn (between LOI and the descent burn it provides about 1950m/s out of the total 3050m/s needed for LOI and landing).</li>
<li>RS-68A Upgraded Delta-IVH. This upgrade is already in engine testing and is badly needed by the DoD, so there&#8217;s a good chance this will work out.  Expected payload capacity I&#8217;ve heard is 27mT for the system.</li>
<li>Instead of carrying a second stretched Centaur as a payload on one of the flights, the Atlas V 552 uses the stretched Centaur as its upper stage.  In order to tank up the LH2, it carries an LH2 drop tank between the lander and the command module.  It gets transfered right after reaching orbit, and gets dumped shortly before TLI.</li>
</ul>
<p>Here are the major components of the system:</p>
<ul>
<li>Command Module: This module is based on the Apollo outer mold line, but only carries two people, and enough life support consumables for the mission.  I budgetted 11,000lb dry and 3250lb of propellant for the capsule (not including RCS propellants).  I assumed hypergols for the stage, with a crappy 314s Isp.  The Apollo CM wet mass was 12.8klb, and the SM weighed 54klb wet, 13.5klb dry.  However, most of the SM mass was due to the CSM performing the LOI burn for the Apollo Stack.  About half of the dry mass of the CSM was the huge main engine, and a good chunk of the remaining mass was electrical equipment and the huge tanks for the 40klb of propellant.  With modern materials, electronics, a smaller crew, solar panels instead of fuel cells, and the much lower propulsive requirements for the Command Module in this architecture, I think 11klb is actually pretty conservative for such a system.  For another comparison the latest CEV numbers I&#8217;ve heard (which are pretty far out of date) were ~18klb for a four person capsule.</li>
<li>Stretched Centaur Lunar Transfer/Crasher Stage:  As mentioned above, this is a dual engine centaur using two RL10A-4-2 engines, but with a 50% barrel stretch to the tanks.  The tanks are actually less than 40% of the dry mass of a centaur stage, but you also need more helium for pressurization of the larger stage&#8230;assuming that the 50% greater propellant load requires a 50% higher dry mass should be a conservative estimate.  The idea of a stretched Centaur shouldn&#8217;t be too crazy when you realize how many iterations General Dynamics, Martin Marietta, and Lockheed Martin have done on the Centaur just in the past 20 years (including 5m diameter Centaurs for use on Titan IV among other things).  The 1750lb for the extended mission kit is also based on numbers from previous papers LM/ULA has published about converting their stages over for longer-duration missions.  Total dry mass I assumed was 9850lb.  Note that the Atlas V 552 performance numbers also include 5400lb worth of Centaur burnout weight, so you only have to provide ~4450lb worth of &#8220;payload&#8221; for the Stretched Centaur.  Also note, that if you tank the stretched Centaur up all the way for launch, it should probably increase the payload capacity of the Atlas V 552 a little compared to a normal Centaur, but for purposes of this analysis we&#8217;re assuming only the nominal payload of a normal Atlas V 552, to be conservative.</li>
<li>Single Stage Lunar Lander/Ascender: This stage takes the crew the rest of the way to the lunar surface after the Centaur has provided the first part of the descent burn, and then provides the ascent burn, and the burn to take the crew to the L2 staging point to rendezvous with the Command Module.  I budgetted 1100m/s for its portion of the descent burn, 100m/s to allow for a 90s hover to find the best landing spot, 2650m/s for the lunar surface to L2 burn, and about 50m/s more for contingencies.  This is probably the most aggressive part of the mission.  For this vehicle, I&#8217;m assuming a piston-pump-fed LOX/CH4 stage, based off of the <a href="http://xcor.com/products/pumps/">piston pump</a> and LOX/Methane <a href="http://xcor.com/products/engines/5M15_LOX-Methane_rocket_engine.html">engine</a> <a href="http://xcor.com/products/engines/3M9_LOX-methane_rocket_engine.html">work</a> XCOR has done  (possibly combined with stuff that we at Masten have done that they haven&#8217;t like gimbals, throttling, etc).  The piston pump requires very low net peak suction head, which allows for very low pressure tanks, that can be made of  the LOX/Cryo-compatible <a href="http://xcor.com/products/cryo_compatable_composites.html">Nonburnite composites</a> that XCOR has been devleoping.  XCOR developed the piston pump and Nonburnite composites explicity for making propellant tanks out of shapes that aren&#8217;t typical for propellant tanks (in their cases to make the CG numbers work, they wanted to do LOX-filled &#8220;wet wings&#8221;).  Using this technology, instead of heavy pressure fed tanks and heavy helium tanks, you have lightweight composite tanks that can actually form part of the load-bearing structure of the vehicle.  As I understand it, based on my recollection of their public statements, the piston pumps they&#8217;re looking at using scale to about enough flow for a 2500lbf engine in a single pump.  By combining them with the 7500lbf engine XCOR developed (with a nozzle extension of course), you have significantly more thrust than you need for landing.  More importantly, you can possibly make the three pumps operate in a redundant fashion, so the loss of one pump can be tolerated at any point in the mission, and the loss of a second pump can be tolerated through most of the mission.  If done right, the pumps could be &#8220;armored&#8221; as XCOR calls it, but placed in such a way that they have removable manways between them and the main compartment that would allow for shirtsleeve troubleshooting/repair (the pump compartments would need to be done in a manner that if something went horribly wrong, that any debris/blast would be directed away from the crew cabin&#8230;but I can imagine a few ways that could be done).  All told, I&#8217;m assuming a 4350lb dry weight, a 9000lb propellant weight, 500lb worth of hardware to be left on the moon, and a 360s Isp.  The LM ascent stage was 4200lb, but held only 65% of the propellant mass, and only about half the propellant volume of this lander, and didn&#8217;t have to do landings, and didn&#8217;t have to support the crew for as long (about 3 days vs. the target 9 days to give you a week on the surface and 2 days in transity to L2).  But as mentioned above, it used pressure fed tanks, with the mass of a helium blowdown system, had to provide significant RCS capabilities since the stage did not have a gimballed main engine, was using crappy 60s era electronics and electrical systems, and had tanks that were entirely non structural, and also didn&#8217;t have access to modern materials like lithium-aluminum or modern composites.  However, the 13,850lb total mass for the lander actually compares pretty well with the 13,510lb currently assumed for the pressure-fed, hypergol-fueld Altair Ascent stage (from this <a href="http://www.nasa.gov/pdf/289914main_fs_altair_lunar_lander.pdf">document</a>), which carries 4 crew for the same mission duration.</li>
<li>Pre-Depot LOX Tank: This ~2.2klb Tank holds ~57.1klb of LOX for the Stretched Centaur.  It includes a docking port (possibly using LIDS technology?), a sunshield, and a Centuar-derived LOX tank.  It gets launched as the sole payload for the Delta-IVH, using up all but about 200lb of its capacity.  But since it is so dense, it might be able to get away with using a shorter (and lighter weight) fairing than is typical for Delta-IVH if that wouldn&#8217;t require lots of expensive aero analysis.  This tank, if launched with the LOX pre-chilled can hang out for over a month waiting for the Atlas V 552 launch.</li>
<li>LH2 Drop Tank: This ~62.5 m^3 tank weighs about 2000lb (with another 2000lb budgetted for connecting structures between the various parts of the launch stack).  It would be housed between the Lander and the Command Module on the Atlas V 552 launch.  It would possibly use 5m tankage derived from the Delta-IV US.  After reaching orbit, the LH2 from this tank would be transfered (using propulsive settling) into the Stretched Centaur.  After the Command Module docks with the Pre-Depot LOX tank, and has transferred all the propellants from that (and discarded the pre-depot LOX tank), the CM and empty LH2 drop tank would separate from the stack, the drop tank would be discarded, and the CM would reattach to the lander much like was done on the Apollo Missions.</li>
</ul>
<p>Now, this mission model isn&#8217;t perfect.  It uses most of the capabilities of the two launchers without a huge amount of margin (except in the fact that the Atlas V 552 with stretched Centaur probably has some margin built in that isn&#8217;t being explicitly called out).  And I&#8217;m not a fan of launching the crew on an EELV with 5 solid strapons.  It would be a lot easier if you assumed the development of something like the Common Upper Stage that ULA has been talking about recently.  With that, you would have tons more margin (since a CUS would add nearly 7mT of capacity to the DIVH, and probably at least 5mT to the Atlas V 552&#8211;possibly enough to go with less or no strapons on the crew launcher).  But it demonstrates that a 2-launch EELV mission using almost no modifications to existing launch vehicles (beyond the Centaur mods) is within feasibility.</p>
<p>The system also has several good things going for it.  First off, it can deliver lunar crew to the surface without a depot.  It doesn&#8217;t need Autonomous Rendezvous and Docking (since the rendezvous and docking can be piloted), or tankers to be developed.  It doesn&#8217;t need HLVs or 10m fairings (everything can fit within a stock Atlas V fairing).  It doesn&#8217;t need really long term LH2 storage in orbit.  It only requires two launches for the mission, and doesn&#8217;t put anywhere near as much launch timing constraints as the ESAS architecture does.  It can provide for cargo missions (~19klb delivered mass to the surface assuming that 2klb of the lander stage is in the form of a removable crew cabin, which just happens to be enough to land a Bigelow Module).</p>
<p>And most importantly, if depots do come into existence, it can immediately take advantage of them.  With just an LEO depot, you can both cut down on the number of EELV launches to just one (and use lower-cost systems like Falcon 9&#8242;s, Zenits, Ariane-Vs, Soyuzes, future commercial RLVs, etc to launch the remaining propellant).  Also by getting rid of the huge LH2 drop tank, you simplify the stack, remove about 15klb worth of hardware from the Atlas stack , dropping it to the point where it can possibly be launched by a 502 launch instead of a 552 launch (since the stretched Centaur provides almost as much propellant as a Phase 1 Atlas, which was supposed to boost the LEO capacity of the single-stick Atlas to almost 30klb).  Or you could use that saved mass to beef up the lander and/or command module for more capable missions.</p>
<p>If you have both a LEO and an L1 or L2 depot, the Centaur can top itself up again that depot, and provide a much larger chunk of the descent burn to the lander stack.  With enough propellant left over to return to LLO then to L1/L2 after separating from the lander, allowing the Stretched Centaur to be reused multiple times.  With such a system you could actually soft-land bigger payloads than the Altair cargo lander&#8230;and you&#8217;d have the capability of making the lander and transfer stage fully reusable.  The transfer stage, since it wouldn&#8217;t see atmospheric flight, reentry, lunar dust, or even particularly bad thermal environments should actually be reusable for several flights&#8211;the RL10 is after all rated for 200 relights.  The lander may be tougher, but by the time you have an L1/L2 depot, you&#8217;ve probably had enough time (and enough surface infrastructure built up) that you can work that out to.</p>
<p>Ok, so maybe it&#8217;s not so bad of an idea after all.</p>
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			<wfw:commentRss>http://selenianboondocks.com/2009/06/random-thoughts-pre-depot-2-launch-manned-missions-using-l2-swingby/feed/</wfw:commentRss>
		<slash:comments>13</slash:comments>
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		<item>
		<title>It&#8217;s Alive!</title>
		<link>http://selenianboondocks.com/2009/05/its-alive/</link>
		<comments>http://selenianboondocks.com/2009/05/its-alive/#comments</comments>
		<pubDate>Fri, 08 May 2009 19:57:38 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[MSS]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=985</guid>
		<description><![CDATA[]]></description>
			<content:encoded><![CDATA[<p><object width="560" height="340"><param name="movie" value="http://www.youtube.com/v/19OJwYdFiiE&#038;hl=en&#038;fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/19OJwYdFiiE&#038;hl=en&#038;fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="291"></embed></object></p>
]]></content:encoded>
			<wfw:commentRss>http://selenianboondocks.com/2009/05/its-alive/feed/</wfw:commentRss>
		<slash:comments>14</slash:comments>
		</item>
		<item>
		<title>More Excuses, Excuses</title>
		<link>http://selenianboondocks.com/2009/01/more-excuses-excuses/</link>
		<comments>http://selenianboondocks.com/2009/01/more-excuses-excuses/#comments</comments>
		<pubDate>Wed, 28 Jan 2009 03:48:08 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[MSS]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=888</guid>
		<description><![CDATA[Two more reasons I haven&#8217;t been blogging much lately: Methinks I may be past-due for an MSS update&#8230;]]></description>
			<content:encoded><![CDATA[<p>Two more reasons I haven&#8217;t been blogging much lately:</p>
<p><object width="480" height="295"><param name="movie" value="http://www.youtube.com/v/DUgCAzIYeUs&#038;hl=en&#038;fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/DUgCAzIYeUs&#038;hl=en&#038;fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="295"></embed></object></p>
<p><object width="480" height="295"><param name="movie" value="http://www.youtube.com/v/eyZgnO7iAVk&#038;hl=en&#038;fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/eyZgnO7iAVk&#038;hl=en&#038;fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="295"></embed></object></p>
<p>Methinks I may be past-due for an MSS update&#8230;</p>
]]></content:encoded>
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		<slash:comments>12</slash:comments>
		</item>
		<item>
		<title>Light Blogging: Excuses, Excuses</title>
		<link>http://selenianboondocks.com/2008/11/light-blogging-excuses-excuse/</link>
		<comments>http://selenianboondocks.com/2008/11/light-blogging-excuses-excuse/#comments</comments>
		<pubDate>Fri, 14 Nov 2008 06:47:04 +0000</pubDate>
		<dc:creator>Jonathan Goff</dc:creator>
				<category><![CDATA[MSS]]></category>

		<guid isPermaLink="false">http://selenianboondocks.com/?p=800</guid>
		<description><![CDATA[Did I mention we&#8217;ve been busy lately?]]></description>
			<content:encoded><![CDATA[<p style="text-align: center;"><a href="http://farm4.static.flickr.com/3028/3025815062_93baa05d39_b.jpg"><img class="aligncenter" title="XA-0.1B First Firing" src="http://farm4.static.flickr.com/3028/3025815062_93baa05d39_b.jpg" alt="First hot firing on XA-0.1B, 11 Nov 2008" width="458" height="302" /></a></p>
<p>Did I mention we&#8217;ve been busy lately?</p>
]]></content:encoded>
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		<slash:comments>7</slash:comments>
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