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In the event of a nominal launch, the tower would be jettisoned midway through the ascent to orbit \u2013 at a point in time where a major issue would result in the capsule simply separating away for an abort \u2013 usually resulting in a splashdown.<\/p>\n
These LAS towers can be seen on the early crewed launch vehicles, having first been tested in 1960 \u2013 when the \u201cBeach Abort\u201d practiced the abort technique on the first production Mercury capsule at NASA\u2019s test facility at Wallops Island.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z42.jpg\" "\\"Z4\\"")
While Gemini used ejection seats, the towers became part of the Mercury and Apollo programs, even earning a place in Hollywood movies, such as when Tom Hanks \u2013 playing Commander Jim Lovell in the movie Apollo 13 \u2013 reached forward to manually jettison the tower during second stage flight during the film\u2019s launch scene.<\/p>\nThe early flights of the Space Shuttle only employed the ejection seat capability, as much as it was hinted using such a system \u2013 only available for a limited time during first stage ascent \u2013 would have provided the escaping astronauts very little chance of survival. The Shuttle mainly relied on abort scenarios involving the return of the crew with the orbiter.<\/p>\n
Thanks to the strict safety record of crewed launch vehicles, the use of the LAS has only been called for once during an actual emergency, with the Russians.<\/p>\n
Space Shuttle
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Another abort \u2013 Soyuz 18A \u2013 aborted in flight, resulting in the crew landing safely near the Chinese border \u2013 however, it is believed this event came after LAS jettison, with the abort carried out by the Soyuz engines.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z32.jpg\" "\\"Z3\\"")
The clear use of the LAS during an abort event is a famous one \u2013 mainly due to the footage finding a large audience on youtube \u2013 as the crew of Soyuz T-10-1 underwent a pad abort, just seconds before their failing vehicle exploded on the launch pad.<\/p>\nThe video shows a line of the Soviet top brass witnessing the dramatic abort, acknowledged only by one General calmly adjusting his collar.<\/p>\n
It was reported that the crew landed safely, just four miles away.<\/p>\n
LAS For Orion:<\/p>\n
For the defunct Vision for Space Exploration (VSE) \u2013 a direct fallout of the Columbia disaster \u2013 crew safety for the next launch system was paramount, as NASA reverted back to a capsule design, with a full Launch Abort System.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z61.jpg\" "\\"Z6\\"")
In 2007, a major trade of several LAS concepts were evaluated by NASA managers, namely the Multiple External (x4) Service Module (SM) Abort Motor concept, the Crew Module Strap On Motors (x4) concept, and the In-Line Tandem Tractor (Tower) concept \u2013 the latter of which was baselined into Ares I\/Orion design.<\/p>\nThe trades request the preferred design should ensure the risk of losing the crew in an abort scenario would be no greater than 1:10, noting such a system is no guarantee for crew survival during an emergency.<\/p>\n
The winning concept \u2013 the Tandem Tractor (Tower) LAS design \u2013 comprised of a Nose Cone, Attitude Control Motor (Eight Nozzles), Canard Section (Stowed Configuration), Jettison Motor (Four Aft, Scarfed Nozzles), Interstage, Abort Motor (Four Exposed, Reverse Flow Nozzles), Adapter Cone, and Boost Protective Cover (BPC).<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z7.jpg\" "\\"Z7\\"")
The primary role of such a system is to save the crew during the \u2018three stages\u2019 of an abort, the first involving the firing of the spacecraft \u2013 in this case Orion \u2013 away from a failing vehicle on the launch pad to a safe distance, before deploying the parachutes on the Orion, for a landing in the Atlantic ocean within a 3450 ft radius due east of the launch pad.<\/p>\nThe second stage of an abort is noted as \u201cmid altitude\u201d \u2013 which has a different characteristic when compared to pad abort. This stage of abort works for up to 150,000 ft, involving the LAS remaining on the vehicle after firing the Orion safely away from the failing vehicle until the point of drogue chute deployment, which becomes necessary at that altitude.<\/p>\n
The final stage of abort, which would still require the LAS, is at an altitude of between 150,000 ft and 300,000 ft \u2013 the latter being the point the LAS would be jettisoned on a nominal flight. After being pulled away from the launch vehicle, Orion would revert to a flight profile similar to that used during the end of a normal mission.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z9.jpg\" "\\"Z9\\"")
During the evaluations, some engineers called for changes to the system. However, due to the mighty struggles of the time \u2013 involving Ares I\u2019s mass to orbit ability, or lack thereof \u2013 the main focus turned to using the LAS, in the event of a successful launch, to still perform a firing, in order to assist Orion\u2019s ride uphill.<\/p>\n\u201cLAS Abort Impulse used for Ascent Assist: Theoretically can increase mass to orbit by 1000 lb. However, additional tension loading on the Command Module requires additional structure that leads to overall decrease in mass to orbit,\u201d noted an extensive NASA presentation (acquired by L2 \u2013 Link to Document).<\/p>\n
Managers also evaluated the use of nozzle inserts in the LAS motors, which would reduce the thrust and thus structural loadings on the vehicle. This option would mitigate any concerns of Command Module (CM) mass penalties.<\/p>\n
\u2018An Alternate Option Using Nozzle Inserts: Reduces Abort Motor Thrust, Increases burn time. Relieves Command Module Compressive load \u2013 no tension loads. Increases the Payload Mass-to-Orbit by ~650 lb,\u2019 added the presentation.<\/p>\n
This option weakened as evaluations progressed, with the final note on such a use for the LAS pointing to only a 400lb mass increase.<\/p>\n
This system has enjoyed one test launch, lofting a boilerplate Orion into the skies of White Sands, New Mexico, durng the successful PA-1 (Pad Abort 1) test in 2010.<\/p>\n
MLAS:<\/p>\n
While abort motors on the Service Module lost out during the trade studies, a new concept came forward called the Max Abort Launch System \u2013 or MLAS (named after Maxime (Max) Faget).<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z51.jpg\" "\\"Z5\\"")
Although it was never publicly admitted, this system was often mentioned by sources as a potential solution towards a growing movement associated with cancelling Ares I and human rating the Ares V, as the Constellation Program (CxP) began to falter.<\/p>\nIt also had the backing of then-NASA administrator Mike Griffin, which would not have come as a surprise, given MLAS was an evolution of two of the original three LAS concepts studied by Constellation, one of which made the LAS trade study in 2007 via a rather amusing hand-drawn sketch, created in 2006.<\/p>\n
The MLAS concept combined the boost protection cover of the service module mounted escape system with the command module mounted motors, in turn reducing the overall height of the vehicle \u2013 something desired by the Ares V HR advocates, who were worried about being able to stack and rollout the vehicle \u2013 with a LAS tower \u2013 under the height restrictions of the Vehicle Assembly Building (VAB) doors.<\/p>\n
The MLAS utilized a \u2018bullet\u2019 boost protection cover over the capsule to house four Mk 70 Terrier solid motors separation motors \u2013 as opposed to locating them on a tower above the capsule.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z11.jpg\" "\\"Z11\\"")
Two orientation parachutes are attached to the top of the fairing to re-orient the vehicle, with the blunt heat shield to aid in fairing separation.<\/p>\nThe design resulted in the aborting vehicle re-orienting immediately after abort motor cut off during a pad abort, but would fly with its nose \u201cinto the wind\u201d on a mid-altitude abort. The orientation parachutes would then activate quickly before the fairing separation.<\/p>\n
In the event of a high altitude abort, the fairing would come off immediately, in order to allow the Command Module Reaction Control System (RCS) to stabilize the vehicle for entry.<\/p>\n
The design of MLAS changed several times during its development, gaining fins for stability during later cycles, becoming more in line with another hand drawn sketch.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z10.jpg\" "\\"Z10\\"")
This time the artist was former Constellation head Scott \u201cDoc\u201d Horowitz \u2013 as seen in the second of two MLAS presentations acquired by L2 (Link to Presentations) \u2013 over a year after Mr Griffin\u2019s conceptual design.<\/p>\nThe final version of the MLAS flight test vehicle weighed in at over 45,000 lbs and was over 33 feet tall \u2013 and this vehicle actually got to fly for real, after being shipped to Wallops for its one and only hop off the ground.<\/p>\n
The pad abort test proper began seven seconds after burnout of some specially attached solid motors, as the vehicle rose into the Virginia morning sky at 6:25am local time on July 8, 2009.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z12.jpg\" "\\"Z12\\"")
Video of the launch showed a perfect test, as the vehicle rose on a stable flight path, before reorientation and further stabilization, followed by crew module simulator separation from the MLAS fairing, and parachute recovery of the crew module simulator.<\/p>\nOther tests were planned for MLAS, including a high altitude abort \u2013 which will involve the fairing being released immediately after abort is called, in order to allow the Command Module Reaction Control System (RCS) to stabilize the vehicle for entry. However, the program was put on the backburner, as the Constellation Program found itself cancelled.<\/p>\n
At this time, the Space Launch System (SLS) will launch Orion with the previously chosen Line Tandem Tractor (Tower) design as its LAS.<\/p>\n
SpaceX LAS:<\/p>\n
Despite being late to the game, when compared to the Constellation development path, SpaceX still came up with an arguably superior system for use with their Dragon spacecraft, a system not only fully integrated into the body of the spacecraft, but one that also holds future uses, through to those that aren\u2019t even related to launch abort.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z14.jpg\" "\\"Z14\\"")
The first major difference relates to the traditional use of solid propellant, mainly because of the speed it can ignite and reach full thrust \u2013 something highly desirable when moving human lives away from a failing rocket.<\/p>\nHowever, Dragon sports a series of eight liquid SuperDraco engines, built into the side walls of the Dragon spacecraft, capable of producing up to 120,000 pounds of axial thrust to drive the Dragon away from its failing launch vehicle.<\/p>\n
SpaceX are deep into developing the engines \u2013 just nine months after their Commercial Crew Development (CCDev) contract noted the LAS is required \u2013 with the latest test fire taking place at the company\u2019s Rocket Development Facility in McGregor, Texas.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z13.jpg\" "\\"Z13\\"")
Referencing back to the benefit of solid motor abort systems, SpaceX\u2019s SuperDraco produced full thrust within approximately 100 milliseconds of the ignition command. It also fired for five seconds, which is the same amount of time the engines would burn during an emergency abort.<\/p>\nAdvantages of the SuperDraco liquid thruster include how the engine can be put through a series of throttling ranges, in turn allowing for redundancy, with SpaceX claiming they could lose one of the eight abort engines and still recover the vehicle and crew successfully. The engines can also be restarted multiple times.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z15.jpg\" "\\"Z15\\"")
Another advantage is the fact it\u2019s not a tower. As noted previously, the LAS tower normally requires jettison shortly after first stage flight. Any failure of this key sequence of ascent would end the mission, given the flight profile wouldn\u2019t be designed for carrying the LAS along for the ride.<\/p>\nBecause the system is integrated into the Dragon itself \u2013 as opposed to departing the spacecraft during jettison \u2013 the spacecraft can technically abort within much longer periods than the tower version. With Dragon returning with the engines on board, they can also be reused on future launches.<\/p>\n
There is also a large amount of commonality between the 18 maneuvering engines built into Dragon and the SuperDraco LAS engines \u2013 bar the fact the SuperDraco engines would burn through propellant 200 times faster.<\/p>\n
The biggest long-term advantage of this system is related to the potential use of the engines to land Dragon back on land propulsively, as seen via SpaceX\u2019s Reusable Falcon 9 concept, which returns all of the launch vehicle and spacecraft hardware to the ground for reuse.<\/p>\n
Parachutes would still be onboard the Dragon, for a contingency event resulting in problems with the SuperDracos, allowing the spacecraft to land on water, as it is currently designed to do.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z17.jpg\" "\\"Z17\\"")
However, Earth isn\u2019t the only landing destination for Dragon, with SpaceX holding ambitions of landing on the Moon and more notably Mars. Nicknamed \u201cRed Dragon\u201d \u2013 SpaceX have made no secret about heading to Mars, even publishing a graphic of their spacecraft touching down on the Red Planet.<\/p>\nSuch a mission is deep into the future, although Elon Musk, SpaceX CEO and Chief Technology Officer, included the full range of use for the SuperDraco\u2019s when announcing his pleasure with the recent test firings.<\/p>\n
\u201cSuperDraco engines represent the best of cutting edge technology,\u201d Mr Musk noted. \u201cThese engines will power a revolutionary launch escape system that will make Dragon the safest spacecraft in history and enable it to land propulsively on Earth or another planet with pinpoint accuracy.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/02\/Z18.jpg\" "\\"Z18\\"")
NASA\u2019s own Mars plans are a mix of old mission outlines and revamped videos, but do show they also have propulsive landing ambitions \u2013 in tandem with large parachutes \u2013 with the latest conceptual Mars mission videos showing massive cargo landers and crew habitats, with the crew riding down to the surface on board the hab lander, touching down under large amounts of propulsive power.<\/p>\nSuch missions are likely to be in the 2030s at the earliest, with the main focus for the entire US space program being the urgency to regain their own domestic crew launch capability, following the retirement of the Space Shuttle.<\/p>\n
The successful development path of the SuperDraco engine has literally pushed SpaceX one step further down the road for NASA and the United States to achieve independence from purchasing seats on the Russian Soyuz \u2013 a vehicle which still uses the same tower LAS that caused one Soviet General to check if his collar was straight.<\/p>\n
(Images via NASA, SpaceX, and L2 content)<\/p>\n
(With the shuttle fleet retired, NSF and L2 are providing full transition level coverage, available no where else on the internet, from Orion and SLS to ISS and COTS\/CRS\/CCDEV, to European and Russian vehicles. <\/p>\n
(Click here: http:\/\/www.nasaspaceflight.com\/l2\/ \u2013 to view how you can access the best space flight content on the entire internet)<\/p>\n","protected":false},"excerpt":{"rendered":"
SpaceX are continuing to make progress with their NASA commercial crew contract, with the latest milestone involving the firing of their SuperDraco thruster engine, an integrated element of the Dragon which will be used as its Launch Abort System (LAS). However, these engines are hoping to gain additional roles, including the ability to land Dragon […]<\/p>\n","protected":false},"author":1,"featured_media":30336,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[8996,1395,8473,367,316],"class_list":["post-40213","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-ccdev","tag-dragon","tag-las","tag-mars","tag-spacex"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40213"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=40213"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40213\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/30336"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=40213"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=40213"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=40213"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}