Launch Abort System:

Historically, Launch Abort Systems (LAS) – or Launch Escape System (LES) – have appeared as towers, attached on top of the crew capsule, ready to “pull” the capsule – and its crew – away from a failing vehicle, be it at the launch pad, or during early ascent.

In the event of a nominal launch, the tower would be jettisoned midway through the ascent to orbit – at a point in time where a major issue would result in the capsule simply separating away for an abort – usually resulting in a splashdown.

These LAS towers can be seen on the early crewed launch vehicles, having first been tested in 1960 – when the “Beach Abort” practiced the abort technique on the first production Mercury capsule at NASA’s test facility at Wallops Island.

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 – playing Commander Jim Lovell in the movie Apollo 13 – reached forward to manually jettison the tower during second stage flight during the film’s launch scene.

The early flights of the Space Shuttle only employed the ejection seat capability, as much as it was hinted using such a system – only available for a limited time during first stage ascent – 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.

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.

Another abort – Soyuz 18A – aborted in flight, resulting in the crew landing safely near the Chinese border – however, it is believed this event came after LAS jettison, with the abort carried out by the Soyuz engines.

The clear use of the LAS during an abort event is a famous one – mainly due to the footage finding a large audience on youtube – as the crew of Soyuz T-10-1 underwent a pad abort, just seconds before their failing vehicle exploded on the launch pad.

The video shows a line of the Soviet top brass witnessing the dramatic abort, acknowledged only by one General calmly adjusting his collar.

It was reported that the crew landed safely, just four miles away.

LAS For Orion:

For the defunct Vision for Space Exploration (VSE) – a direct fallout of the Columbia disaster – crew safety for the next launch system was paramount, as NASA reverted back to a capsule design, with a full Launch Abort System.

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 – the latter of which was baselined into Ares I/Orion design.

The 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.

The winning concept – the Tandem Tractor (Tower) LAS design – 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).

The primary role of such a system is to save the crew during the ‘three stages’ of an abort, the first involving the firing of the spacecraft – in this case Orion – 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.

The second stage of an abort is noted as “mid altitude” – 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.

The final stage of abort, which would still require the LAS, is at an altitude of between 150,000 ft and 300,000 ft – 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.

During the evaluations, some engineers called for changes to the system. However, due to the mighty struggles of the time – involving Ares I’s mass to orbit ability, or lack thereof – 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’s ride uphill.

“LAS 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,” noted an extensive NASA presentation (acquired by L2 – Link to Document).

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.

‘An Alternate Option Using Nozzle Inserts: Reduces Abort Motor Thrust, Increases burn time. Relieves Command Module Compressive load – no tension loads. Increases the Payload Mass-to-Orbit by ~650 lb,’ added the presentation.

This option weakened as evaluations progressed, with the final note on such a use for the LAS pointing to only a 400lb mass increase.

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.

MLAS:

While abort motors on the Service Module lost out during the trade studies, a new concept came forward called the Max Abort Launch System – or MLAS (named after Maxime (Max) Faget).

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.

It 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.

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 – something desired by the Ares V HR advocates, who were worried about being able to stack and rollout the vehicle – with a LAS tower – under the height restrictions of the Vehicle Assembly Building (VAB) doors.

The MLAS utilized a ‘bullet’ boost protection cover over the capsule to house four Mk 70 Terrier solid motors separation motors – as opposed to locating them on a tower above the capsule.

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.

The design resulted in the aborting vehicle re-orienting immediately after abort motor cut off during a pad abort, but would fly with its nose “into the wind” on a mid-altitude abort. The orientation parachutes would then activate quickly before the fairing separation.

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.

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.

This  time the artist was former Constellation head Scott “Doc” Horowitz – as seen in the second of two MLAS presentations acquired by L2 (Link to Presentations) – over a year after Mr Griffin’s conceptual design.

The final version of the MLAS flight test vehicle weighed in at over 45,000 lbs and was over 33 feet tall – and this vehicle actually got to fly for real, after being shipped to Wallops for its one and only hop off the ground.

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.

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.

Other tests were planned for MLAS, including a high altitude abort – 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.

At this time, the Space Launch System (SLS) will launch Orion with the previously chosen Line Tandem Tractor (Tower) design as its LAS.

SpaceX LAS:

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’t even related to launch abort.

The first major difference relates to the traditional use of solid propellant, mainly because of the speed it can ignite and reach full thrust – something highly desirable when moving human lives away from a failing rocket.

However, 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.

SpaceX are deep into developing the engines – just nine months after their Commercial Crew Development (CCDev) contract noted the LAS is required – with the latest test fire taking place at the company’s Rocket Development Facility in McGregor, Texas.

Referencing back to the benefit of solid motor abort systems, SpaceX’s 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.

Advantages 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.

Another advantage is the fact it’s 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’t be designed for carrying the LAS along for the ride.

Because the system is integrated into the Dragon itself – as opposed to departing the spacecraft during jettison – 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.

There is also a large amount of commonality between the 18 maneuvering engines built into Dragon and the SuperDraco LAS engines – bar the fact the SuperDraco engines would burn through propellant 200 times faster.

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’s Reusable Falcon 9 concept, which returns all of the launch vehicle and spacecraft hardware to the ground for reuse.

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.

However, Earth isn’t the only landing destination for Dragon, with SpaceX holding ambitions of landing on the Moon and more notably Mars. Nicknamed “Red Dragon” – SpaceX have made no secret about heading to Mars, even publishing a graphic of their spacecraft touching down on the Red Planet.

Such 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’s when announcing his pleasure with the recent test firings.

“SuperDraco engines represent the best of cutting edge technology,” Mr Musk noted. “These 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.”

NASA’s own Mars plans are a mix of old mission outlines and revamped videos, but do show they also have propulsive landing ambitions – in tandem with large parachutes – 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.

Such 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.

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 – a vehicle which still uses the same tower LAS that caused one Soviet General to check if his collar was straight.

(Images via NASA, SpaceX, and L2 content)

(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. 

(Click here: http://www.nasaspaceflight.com/l2/ - to view how you can access the best space flight content on the entire internet)

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Orion Testing Latest:

Following an uncertain period in its early life, Orion has been refocused towards a Beyond Earth Orbit (BEO) exploration role, refined from its previous dual role in Low Earth Orbit and beyond, as previous prescribed by the now defunct Constellation Program (CxP).

An array of commercial vehicles are currently competing for NASA’s long-term affections via the CCDev (Commercial Crew Development) contracts, as they prepare to take over the crew transportation needs in Low Earth Orbit (LEO).

This still leaves Orion with a distinct lack of defined missions, with only pre-planned – as opposed to confirmed mission outlines – to Near Earth Objects (NEO), ahead of an eventual role in the first human mission to Mars.

Most of the problems with the long term manifest relate to the ongoing “political” delays in pushing forward with the Space Launch System (SLS), which is supposed to be the launch vehicle of choice for Orion’s BEO missions.

The only preliminary SLS manifest in recent months shows Orion will opening two BEO missions, starting with an unmanned trip around the Moon in 2017, prior to a four year gap to SLS-2, which would be an identical mission, only this time the 2021 lunar flight would be crewed.

Sources claim it is likely – as much as no hard evidence has yet been produced – that this timeline will move significantly to the left, especially in light of the “threat” a commercial carrier would likely propose being such missions far cheaper and sooner.

Should NASA eventually announce SLS, in line with the aforementioned preliminary schedule, it is highly questionable the vehicle would survive the resulting political fallout.

As it stands, the first real BEO mission of substance for Orion involves a long duration flight to a NEO in around 2025.

Ironically, it will be a commercial launch vehicle which will provide Orion with its first trip into space, via the Orion Flight Test (OFT-1) in 2013, when a Delta IV will send an unmanned MPCV on a short orbital test flight from Cape Canaveral.

With Orion work now picking up a good pace in its development stage, several milestones are being reached in Denver, with the black GTA Crew Module – which was constructed at the Michoud Assembly Facility (MAF) in New Orleans – mated with the LAS for the first time at the Lockheed Martin Reverberant Acoustics Lab (RAL) in Denver during the week of August 8-12.

“The completed Launch Abort Vehicle (LAV) assembly has been translated into the acoustic test cell for the start of the integrated acoustic testing,” noted Orion processing notes (L2).

Click here for recent Orion articles: http://www.nasaspaceflight.com/tag/orion/

“All of the handling Mechanical Ground Support Equipment (MGSE) and procedures performed as anticipated and no significant issues were noted during the mate operation.”

This testing – also known as the “shake and bake” test – took place at Lockheed Martin’s Waterton facility in Denver, as the Orion stack was exposed to a series of tests which simulate the sound pressure levels that the vehicle will encounter during launch, which can exceed 160 decibels.

“Acoustic Testing Conducted on Integrated Ground Test Article: Acoustic testing was conducted on the Ground Test Article (GTA) Launch Abort Vehicle (Comprised of the launch abort system and the crew module). Preliminary data from the test looks positive,” added the processing notes.

“Next, the team will remove the launch abort system from the crew module and outfit the launch abort system with the fillet and ogive panels for the next test configuration. The next round of acoustic testing will occur in mid-September.”

In other testing, Orion’s Closed Loop Entry Test of flight software on flight computer was deemed a success, following work at Lockheed Martin’s Integrated Test Lab.

“The Orion MPCV Program recently executed a set of tests on the initial configuration. The tests demonstrated the successful integration of avionics hardware, flight software, simulation, ground support equipment and lab infrastructure,” noted notes continued.

“These tests are part of a series of Integrated Sync Points (ISP) that demonstrate integrated avionics and software vehicle functionality. The three ISPs are significant milestones in the development of the Orion Avionics and Software system, demonstrating the Entry Guidance, Navigation, and Control (GN&C) system running closed loop on the Orion flight computers with an integrated simulation.

“It brings together five major threads of the onboard and ground systems: Onboard Avionics, Onboard Flight Software, Electrical Ground Support Equipment, Data and Simulation systems.”

Orion testing is also taking place outside of Denver, with high level Computational Fluid Dynamics (CFD) modeling of re-entry heating environments now completed at the CUBRC test facility in Buffalo, New York.

“The Crew Exploration Vehicle Aeroscience Panel (CAP) aerothermodynamics team concluded the 91-CH high thermodynamic crew module heating test,” notes added.

“This test measured the impact of shock layer gas chemistry on heating to the Crew Module aft bay heatshield, and provided validation data for high fidelity CFD modeling of re-entry heating environments.

“This data, along with data from the planned follow-on 113-CH test, will provide improved accuracy nominal environments, lower heating rate uncertainties, and critical physics data to improve coupling aerothermal surface environments to the in-depth Thermal Protection System (TPS) thermal response modeling.”

Orion’s on orbit steering hardware – otherwise known as its Reaction Control System (RCS) – has also been put through a series of aeroheating tests at NASA’s Langley Research Facility (LaRC), which is also the center that has carried out the recent water impact drop tests.

“The aerothermodynamics team concluded the 95-CH crew module RCS aeroheating test at the NASA LaRC’s Mach 10 Facility. The primary focus of the test was to use Temperature Sensitive Paint (TSP) to show backshell regions of augmented heat flux due to RCS firings.

“Unlike discrete thermocouple temperature measurements, TSP provides a global heating map which identifies the maximum heating locations and the complete spatial distribution of augmented heating due to RCS jet interactions. The data will be used to verify and validate RCS heating models from previous CAP testing with discrete gauges.

“This test was the first CAP aerothermodynamics test to include the current launch abort system well design and the updated backshell angle.”

(Images: Via L2 content and NASA. This article was collated from L2′s new Orion and Future Spacecraft specific L2 section, which includes, presentations, videos, graphics and internal updates on Orion and other future spacecraft.

(L2 is – as it has been for the past several years – providing full exclusive future vehicle coverage, available no where else on the internet. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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JDTV:

The first test of the giant parachutes that will be tasked with easing Ares I’s five segment Solid Rocket Motor First Stage’s return to earth for splashdown in the Atlantic didn’t go fully to plan, with damage sustained to the JDTV – which mimics the Ares I First Stage, if not by appearance – during its debut drop test last summer.

An Integrated Product Team (IPT) conducted a design and analysis review of modifications to the JDTV, which resulted an increase to the strength of the buckled components, following its hard landing, and the inclusion of break-away fins – which were re-manufactured prior to the upcoming test.

This should avoid future damage to the reusable test vehicle, which is deployed out of the back of a US Air Force C-17 transport on an extraction pallet.

Teams successfully completed the tow tests of the new C-17 air drop extraction (pallet) system to be used on the upcoming JDTV parachute drop tests. A new extraction system was required since the standard extraction system utilized by the Air Force has a 60,000-lb extraction limit.

“The new extraction system uses Vectran rope, along with modified standard Army 15-ft drogue, and 28-ft extraction parachutes that have been structurally reinforced with Kevlar radials,” noted Ares Program information.

“The test consisted of towing the modified drogue and extraction chutes with the Vectran rope behind a C-17. The test objectives were to measure and record the tow forces of the parachutes at various air speeds and parachute reefing positions and visually record their proper deployment.”

The drop will take place at 10am on February 26 – weather permitting – at the US Army Yuma Proving Ground, located close to the Arizona-California border, which has been the site for most of the drop tests for the Constellation program.

Last summer, the Orion Parachute Test Vehicle (PTV) – a truncated looking Orion – suffered a failure, ripping off its parachutes and crashing to the ground, after it became inverted following extraction from a C-17 aircraft.

The vehicle is now scrapped, located in the “boneyard” of the Army base.

In 2007, the third Parachute Drop Test (PDT) – which was testing a pilot parachute for the Constellation program – resulted in the Drop Test Vehicle (DTV) being destroyed.

The test vehicle hit the ground with such velocity, special excavation equipment was required to recover the nose of the DTV – which was buried 30 feet below the surface. All other tests have been deemed a success.

MLAS (Max Launch Abort System):

Specially funded outside of the Constellation program, under the leadership of former Constellation head Scott Horowitz and NASA Engineering and Safety Center (NESC), the MLAS is confirmed to be just a month away from an opening salvo of tests.

First revealed by NASASpaceflight.com last year, several presentations on L2 outline the concept that appears to have grown out of the LAS trade studies in 2007.

During that trade study, three candidates were evaluated, 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 – with the latter then baselined into Ares I/Orion design.

The trade study presentation – also on L2 – shows a ‘hand drawn sketch’ by former NASA administrator Mike Griffin, dated March 22, 2006, that is believed to be the origin of MLAS.

The “alternative” Launch Abort System was originally set to carry out a pad abort test in September, 2008. However, concerns the system is far too heavy for Ares I, and the continued push to baseline the traditional “tower’ LAS, initially led to rumors the project had been cancelled.

Although never specifically noted as anything other than an alternative “fall back position” system, it is possible MLAS is part of a backup plan for a Human Rated Ares V, given initial studies into man-rating the huge vehicle note it would be impossible to stack with the current LAS tower, due to height restrictions regarding vehicle integration inside the Vehicle Assembly Building (VAB).

With MLAS on top of Ares V, the vehicle could be stacked within current restrictions. A Human Rated Ares V would only become a reality if Ares I development was ceased, and the alternative options of EELV and Direct’s Jupiter vehicles failed to win approval under such a scenario.

For now, the Constellation program are only classing MLAS as an “alternative” to the LAS tower, even though it would be near unthinkable to make such a large change to Ares I at this stage of development.

“Like the leading NASA launch abort concept, MLAS offers a safe, reliable method of pulling the spacecraft capsule and crew out of danger in the event of an emergency on the launch pad or during the climb to Earth orbit,” noted NASA in releasing the date of the pad abort test.

“A NASA team is preparing to demonstrate an alternate escape system design to explore different technological approaches. Named after Maxime (Max) Faget, a Mercury-era pioneer, the Max Launch Abort System (MLAS) concept will be validated by conducting an unmanned pad-abort test in March at NASA’s Wallops Flight Facility, Wallops Island, Va.”

The dates listed involve a parachute drop test of the MLAS on March 5, followed by the pad abort test on March 27.

Representatives from the Sounding Rockets Program Office and NASA Sounding Rocket Operations Contract, (NSROC), have provided technical support associated with the solid rocket motor systems used by MLAS. NSROC also play a major role in vehicle hardware and mechanical GSE (Ground Support Equipment) fabrication.

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