LiveScience: ULA edging towards commercial space travel

[docm]

LiveScience: ULA edging towards commercial space travel....<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p><b>Atlas Boost for Space Tourism, Space Colonization</b><br /><br />If it was good enough for Mercury astronaut John Glenn back in 1962, it must be good to go to hurl tourists into Earth orbit and beyond.<br /><br />That was the one-two punch delivered at the recent Space Technology & Applications International Forum (STAIF) held February 11-15 in Albuquerque, New Mexico.<br /><br />Jeff Patton of the Business Development & Advanced Programs of the newly formed United Launch Alliance (ULA) spotlighted that a “potential new market for construction, crew and cargo delivery to low Earth orbit” can be serviced by the Atlas V 401 booster.<br /><br />ULA’s Patton detailed a capsule-based passenger transfer vehicle that sits nicely atop the Atlas - a craft based on the design work and reentry technology used in the Genesis, Stardust and several Mars missions.<br /><br />NASA has identified a term that is used for human flight called “Black Zones” Patton said, a phrase that defines any period of flight when an abort would be unsafe for the passengers.<br /><br /><font color="yellow"><b>A great deal of effort was spent during work on the Orbital Space Plane - a precursor design to the current Orion Crew Exploration Vehicle - an exercise that identified potential Black Zones and eliminating them by modifying the Atlas Evolved Expendable Launch Vehicle (EELV).<br /><br />Patton’s bottom line: Atlas V 401/402 boosters are well suited for low Earth orbit human spaceflight and taking on a roster of commerical human spaceflight needs.<br /><br />Also at STAIF, Michael Holguin of Lockheed Martin Space Systems Corporation pointed to using the Atlas and the Centaur upper stage to propel people, habitats and hardware to the Moon and Mars, calling it a reliable, robust, and safe approach to</b></font></p></blockquote> <div class="Discussion_UserSignature"> </div>

 

[comga]

In an AIAA article published a year or so ago two engineers from Lockheed Martin showed how the trajectory could be optimized to eliminate all "black zones". That is, an abort would be survivable at all points in the trajectory. Furthermore, the cost in payload when compared to a mission optimized for mass-to-orbit, was not great. <br /><br />The Atlas V 401 is not modified. The trajectory is.<br /><br />PS One clever element of the design is that the "escape tower" is replaced with thrusters below the heat shield. If they are not used for an abort on the way up, they are used for orbital insertion, circularization, and deorbit.

 

[gunsandrockets]

"PS One clever element of the design is that the "escape tower" is replaced with thrusters below the heat shield. If they are not used for an abort on the way up, they are used for orbital insertion, circularization, and deorbit."<br /><br /><br /> I believe the VA capsule of the Soviet TKS spacecraft project used a similar design. The escape tower of the capsule doubled as the deorbit propulsion system.<br /><br />I'm not sure but I think that just as a pure launch escape system, placement of the rocket behind the capsule provides mass advantages. Supposedly a smaller rocket suffices compared to a traditional escape tower position. I could certainly see why that could be the case, especially during the launch phase of maximum dynamic pressure.<br /><br />"In an AIAA article published a year or so ago two engineers from Lockheed Martin showed how the trajectory could be optimized to eliminate all "black zones". That is, an abort would be survivable at all points in the trajectory. Furthermore, the cost in payload when compared to a mission optimized for mass-to-orbit, was not great. The Atlas V 401 is not modified. The trajectory is."<br /><br />I believe the heart of the NASA 'black zone' criticism of the Atlas did not have to do with the Atlas V 401, but of use of a three core Atlas launch vehicle for the purpose of launching the Orion CEV. The three core Atlas didn't have enough payload margin to change trajectory to exclude black zones and still deliver the CEV to orbit.<br /><br />Of course the real problem wasn't that the Atlas was too incapable, the problem was NASA insisting on a CEV that was too massive! Easy design changes could have been made to fit the CEV within the existing Atlas/Delta capability. The capsule could have been downsized to a more reasonable 4 to 4.5 meter diameter, or the TEI propellant stage could have been carried up by the Ares V instead of having the Crew Launch Vehicle haul it up. <br /><br /><br />

 

[josh_simonson]

If the launch abort rockets are solid fueled then it doesn't make sense to bring them all the way to orbit for use as a de-orbit thruster. This is because to get the solid rocket to space you require ~6 times it's weight in very high ISP second stage fuel - trading 460 ISP fuel for 250 ISP fuel is a very, very bad trade. To make matters worse, LAS systems have a very poor mass fraction due to the high thrust needed for a short duration. The grain is thin with a large surface area, which makes the area/volume of the casing low, and the casing needs to contain the pressure so it's also heavy.<br /><br />Especially with a centaur second stage it makes much more sense to simply drop the LAS motors un-used or fire and drop them after S1-sep as in the russian design if you like to live dangerously. Rather the way to go for de-orbit is to add RCS/OMS fuel because this fuel has a much higher ISP (~300), and enlarging the existing tanks on this system has a incremental fuel fraction of ~98% compared to the ~40% for a LAS motor. <br /><br />In order to beef up the OMS to a sufficient thrust level for abort, the engine would need to be huge, which is a huge hit to the fuel fraction of the spacecraft. <br /><br />Without some mythical high-isp, high-thrust but lightweight engine, carrying the LAS to orbit will not make sense until the payload opportunity cost plus refurbishment cost of the LAS is less than the cost of expending the LAS after the boost phase. <br /><br />Perhaps some launch schemes, such as liquid fueled air-launch, will not require an LAS due to relatively benign failure modes and the initial altitude being high enough for a parachute alone to save the crew.

 

[bpfeifer]

"I do not think there is a performance increase by having the abort rockets in the aft. That placement would not give better performace at max Q. "<br /><br />I'm no expert, but I've seen other posts discussing the value of placing abort rockets at the capsule base vs on a tower. I think it might have even been mrmorris...<br /><br />There are two benefits to placing the rockets at the base of the capsule. First , you save the weight of the tower, which can be considerable. The second, is that abort rockets at the base are directly in-line with the direction of thrust while those on a tower must be angled away from the capsule. This angling results in significant wasted thrust. <div class="Discussion_UserSignature"> Brian J. Pfeifer http://sabletower.wordpress.com<br /> The Dogsoldier Codex http://www.lulu.com/sabletower<br /> </div>

 

[gunsandrockets]

"The Russian system design that I think you are referring to used the abort rockets to add velocity to the vehicle during ascent when the abort rockets were no longer required. There were multiple rockets which fired all at once for an abort and in pairs for the case when they were used to add velocity during the ascent. These rockets were on the rear end of the spacecraft."<br /><br />No confusion on my part. I was not talking about the Kliper spacecraft, one proposed arrangement of the Kliper's launch escape system fits what you describe...<br /><br />http://www.russianspaceweb.com/kliper_sas_3.jpg<br /><br />http://www.russianspaceweb.com/kliper.html<br /><br />...excerpt about Kliper follows...<br /><br />"Emergency escape profiles"<br /><br />"In the original concept, the Kliper would be topped with the emergency escape rocket, which would pull the glider away from the failing booster during the launch, as it was done onboard the Soyuz spacecraft. However in the effort to save weight and simplify aerodynamic flow around the nose of the orbiter, engineers decided to move the escape rockets to the launch vehicle adapter on the tail of the spacecraft, where they could double as the orbital maneuvering system."<br /><br />No, the Kliper is quite different from the TKS spacecraft that I was originally talking about...<br /><br />http://www.russianspaceweb.com/tks.html<br /><br />http://www.svengrahn.pp.se/histind/Almprog/tksalm.htm<br /><br />...the VA capsule of the TKS spacecraft uses a very interesting design for it's tower launch escape system...<br /><br />http://www.svengrahn.pp.se/histind/Almprog/almcap2x3.gi

 

[gunsandrockets]

"I do not think there is a performance increase by having the abort rockets in the aft. That placement would not give better performace at max Q. "<br /><br />The Atlas V manned capsule launch escape rocket is in the tail, behind the capsule and within a launch fairing. The reasoning that I read claimed that the gas pressure generated between the capsule and the booster by the firing of the escape system helps to overcome a low pressure zone in the tail of the capsule that is troublesome during max Q. Sounds plausible.

 

[gunsandrockets]

"Is their concept to use the abort rockets for extra delta V when they are no longer required?"<br /><br />Don't know. Could be I suppose. The Atlas V 401 has plenty of payload all by itself to place a large enough manned spacecraft into orbit, so I wouldn't see the need.<br /><br /> I wish Lockheed-Martin would go public with more details of their manned spacecraft concept for the Atlas V 401!

 

[gunsandrockets]

"In an AIAA article published a year or so ago two engineers from Lockheed Martin showed...PS One clever element of the design is that the "escape tower" is replaced with thrusters below the heat shield. If they are not used for an abort on the way up, they are used for orbital insertion, circularization, and deorbit."<br /><br />Could you post a link to that paper?

 

[comga]

josh_simonson: "If the launch abort rockets are solid fueled then it doesn't make sense to bring them all the way to orbit"<br /><br />Your clear explanation is a good example of why I ask questions in these forums. That makes good sense, although it probably isn't as simple as a direct trade of 200 sec ISP solid fuel for 350 sec ISP second stage fuel. (The trade also "costs" the launch escape tower, and the fact that the solid fuel is carried to several miles altitude before being "traded" for fuel on the ground, in addition to the aerodynamic benefit at Max-Q as cited by gunsandrockets and the angling as cited by bpfeifer.)<br /><br />As for gunsandrockets discussing "the NASA 'black zone' criticism of the Atlas", that wasn't what I was referring to. All I said was that the LM engineers had closed out all the black zones. That said, his comments on NASA's drive to the CLV by requiring it to carry too many things and too much mass are right on target. I could not agree more.<br />

 

[cuddlyrocket]

NASA is looking at a number of configurations for the launch abort system - I remember a hand-drawn diagram from Mike Griffin for the rockets to be mounted around the side of the sevice module.<br /><br />As for using the LAS to supplement the launch, this has also been looked at by NASA. Apparently using the Tower LAS you get about 1,000 lb extra payload into orbit. However Scott Horowitz is unhappy about using the LAS in this mode. Partly because you effectively make it a 3-stage vehicle, thereby decreasing reliability. But mostly because an escape system should not be given any other task as this detracts from its ability to carry out its prime task.

 

[solarspot]

Another point; doesen't the launch escape system exert several G's (6-10?) when fired? I thought that was too high for anything other than an emergency, just reffering to the crew. I wouldn't want to weigh 1000-1500 pounds in my seat just for the de-orbit burn! haha

 

[docm]

Given the choice of a massive 10G kick in the buns and sticking around for a booster failure, or even the edge of one, I'll take the former & worry about the consequences later <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

 

[holoman]

Post deleted by holoman

 

[rocketman5000]

stop trolling