Monthly Archives: July 2009

Really Taking Shape Now

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Yesterday, yet another portion of the Ares I-X rocket was stacked on the Mobile Launch Platform in Kennedy’s Vehicle Assembly Building. Now that super stack 1 is up and on, the 327-foot rocket is more than half way assembled and the team is getting excited as they watch it take shape in High Bay 3.  
 

Super stack 1 is composed of the fifth segment simulator, forward skirt, forward skirt extension, frustum and interstages 1 and 2. It also includes two internal elements – the roll control system and the first stage avionics module – as well as the parachute system housed in the forward skirt extension. The team used a massive overhead crane, specially adapted for I-X use, to place it on top of the forward motor segment.

Over the next month, four more super stacks with the final pieces of hardware (including the simulated crew module and launch abort system) will be mated, finishing off the stacking operations for the rocket. So, in about a month, NASA is going to be able to show off one of the biggest rockets the world has ever seen!

Ares I-X is scheduled to roll out to launch complex 39B just four days prior to its targeted liftoff of October 31.

Aft Center Section is Up…Over…and On

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With its telltale “Z” stripe showing, the aft center section of the Ares I-X first stage booster is hoisted into place. Using a 325-ton capacity crane, the aft center is being lifted so it can be joined to the aft section already in place on mobile launch platform 1. 

Last week the aft section was placed on MLP 1 and locked down by four huge bolts — each of which has 750,000 pounds of tension in them when torqued down. The 100 foot horizontal and 90 foot vertical journey from the center transfer aisle of the VAB into VAB high bay 3 takes many hours due to the methodical nature of handling and moving solid rocket motor segments loaded with hundreds of tons of explosive propellant. 

 

Once the aft center section is in place, the forward center section will soon be brought over and finally the forward section will be joined to the other three. Once we have all 4 sections stacked, we will be ready for the first non-rocket motor section called Super Stack 1.

 

Vibrations and Loads

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It may be pretty obvious, but it’s worth noting that one of the main purposes of a flight test is to do a little trailblazing. We can and should test processes and procedures as early in a program as possible so we can identify any areas for concern and target problem spots that need some improvement. The more we build and fly, the more we learn. As a flight test, Ares I-X is doing that exact thing for the Ares I rocket.

One aspect of rocket building that we are paying special attention to lately is vibration. Rockets vibrate a lot. In the case of Ares I-X, the vibrations come from several sources. Among them are the vibration and sound waves caused by the lift off of the rocket, the burning of rocket propellant and the act of plowing through the atmosphere at over four times the speed of sound.

The vibration that is produced by the burning of the solid rocket propellant in the first stage booster is called thrust oscillation. These vibrations — or oscillations — come in the form of waves, which travel up and down the length of the rocket like a musical note through an organ pipe. One of the biggest challenges in any rocket design is developing avionics (aviation electronics) that can function in this vibrating environment.

Vibration is not just a rocket issue, though. All electronic hardware is tested for its ability to handle shock and vibration. An MP3 player, for example, has to be tested for its ability to handle the vibrations from someone walking or jogging while holding it, placing it on a countertop, or accidentally dropping it on the floor. However, compared to the workout that Ares I-X’s avionics receive, your MP3 player has got it easy. Imagine shaking that MP3 player inside an automatic paint can shaker for two minutes while continuing to play your favorite tunes. That’s kind of what the electronics of the I-X are up against.

Two of the most important sets of electronics on Ares I-X are the thrust vector control (TVC) system, which steers the rocket, and the flight termination system (FTS), which is used to “self destruct” the rocket if it veers off its proper flight path.

Recently, NASA engineers at Langley Research Center upgraded to a new, higher-precision computer model, which allowed them to more closely examine the vibration environments on Ares I-X. With this more precise model, they observed that some areas of the rocket had vibration levels — called “G-loads” or just “loads” in engineer-speak — that were slightly higher than the levels the TVC and FTS were initially tested to handle.

How much is “slightly?” Well, Langley’s engineers are still examining the computer models to get the full answer, but right now the observed vibration levels are measured in hundredths of a gravity (or “G”). That would be like giving the automatic paint shaker one extra shake every minute — you wouldn’t notice the difference, but your MP3 player might.

The computer models have found that the biggest effects of the thrust oscillation on Ares I-X come between 70 and 90 seconds into the flight, when the rocket is about three fourths of the way through its ascent. Before 70 seconds and after 90 seconds the vibration levels are fine, but for those 20 seconds we haven’t fully verified that we can still steer the rocket with the TVC or send the signal to self-destruct the rocket and end the flight with the FTS if it veers away from its projected path.

So that’s the challenge the Ares I-X team is facing right now. Fortunately, we have several options for handling the situation, and the I-X team is looking at all of them to determine the best way forward:

  • First, the team is analyzing the new vibration models more closely to make sure that the components really do exceed their limits, and if so, by how much.
  • Next, if the team determines that the vibrations do exceed the design limits of the TVC or FTS, test engineers could re-test the components to operate at the higher vibration loads. If the components pass the re-testing, the stacking and assembly of the rocket will continue as planned.
  • However, if the test team finds that the avionics could still have problems at the higher vibration levels, they may need to make some modifications to the vehicle like adding additional support structures to dampen the vibrations or isolate the hardware from the vibrations’ effects.

Since the beginning of the I-X mission, NASA has worked very closely with the Air Force’s 45th Space Wing’s Range Safety team, which controls the range at Kennedy Space Center to make sure that every precaution is taken to ensure a safe launch and a safe flight. The 45th Space Wing will continue to work alongside the I-X team to evaluate the situation and make sure that the best decision is made.

The bottom line is that we’re not launching anything until it’s deemed safe by NASA and the U.S. Air Force, even if it takes a little longer to get it right. We’re all excited about watching Ares I-X take flight later this year, but really, we might end up learning just as much from these steps along the way as we do on launch day.

Supersize Me!

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The Super Stack 1 assembly is now complete with the mating (stacking) of the forward assembly to the fifth segment simulator. Stack one is made up of eight individual pieces: interstages 1 and 2, the frustum, the forward skirt extension, the forward skirt and the aft, center and forward segments of the fifth segment simulator. It also includes two internal elements, the roll control system and the first stage avionics module.

All five super stack assemblies are now complete in High Bay 4 of the VAB and are ready for stacking on the mobile launcher platform in High Bay 3 later this month.

Just so you know, the reason the rocket is separated into these super stacks has to do with the height and weight of each piece for crane loads during lifting operations.

Super Stack 2: Upper Stage Simulator “Tuna Cans” segment 1

Super Stack 3: Upper Stage Simulator “Tuna Cans” segments 2, 3, 4, 5

Super Stack 4: Upper Stage Simulator “Tuna Cans” segments, 6, 7

Super Stack 5: Spacecraft Adapter, Service Module, Crew Module and Launch Abort System

Ares I-X: Let the Stacking Begin…

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Stacking is set to begin for the Ares I-X vehicle on Wednesday, July 8 in the Vehicle Assembly Building at Kennedy Space Center. It’s been a long time since the workers in the VAB have seen a new vehicle. In fact, it’s been 25 years since a new vehicle was stacked.
Following nearly three years of work by thousands of dedicated team members, the Ares I-X vehicle is ready for stacking on the Mobile Launch Platform, or MLP, in the Vehicle Assembly Building at Kennedy Space Center.

Over the last week, the management team has met for reviews. Today, a “go” was given for the stacking operations. All of the modification work has been completed in VAB High Bay 3, as well as the Mobile Launch Platform, in preparation for the new Ares I-X vehicle.

Tomorrow, the Ares I-X aft assembly, composed of the aft skirt and aft motor segment, will be rolled from the Rotation Processing and Surge Facility to the VAB and lifted by overhead crane and placed on the MLP. (Be sure to check out the KSC gallery for photo updates.)

Over the next month, the stacking operations will continue with the additional motor segments, simulated upper stage segments and the vehicle will be completed when the simulated crew module and launch abort system is added to the top. (There will be a time-lapse camera. NASA will be posting video and images.)

We will keep you posted on this blog, on our Facebook page and Twitter.

Let the stacking begin!

Update from the Mate Review

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Here’s a quick update from Ares I-X Mission Manager, Bob Ess

Earlier thisweek, the I-X and Constellation team completed a really significant milestone –aMate Review.  The purpose of this review is to assess our readiness tobegin stacking operations in the Vehicle Assembly Building at Kennedy SpaceCenter.

Right now theAres I-X rocket is put together in big pieces called “super-stacks”. Webegin our stacking operations when we put the first part of the first stagebooster on the Mobile Launch Platform. We’ll follow that with these five“super-stacks”.  

During the review, wediscussed the mission’s progress to date, key technical and operational itemsand, of course, the readiness of the procedures and facilities for the stackingoperations. This review was attended by members of the Constellation Programand directors of the involved NASA centers as well as independent (outsideNASA) reviewers.

The review went very welland the review board agreed on a set of procedural guidelines and next-stepactions.  The mating (stacking) of the aft skirt on the MLP is the firststep in assembling I-X. As this is the foundation of our rocket, wehave spent a lot of time assessing our aft skirt and making sure it canadequately handle the needs for I-X. Some of that analysis is not quitecomplete so as a group we decided to wait until the middle of next week when weknow more about our loads analysis before we started this particular matingoperation.

Also at the Mate Review, weagreed upon a set of “constraints” that are mini-review points for some key to-doitems.  This allows the team to get together and assure that sufficientprogress has been made on these items before we undertake some of the critical stackingevents.   The constraints are mostly centered on the completion ofseveral ongoing loads analyses and the completion of some planned testing in theVehicle Assembly Building.
 
Overall, it was a very good,interactive review by the team and we are very please to have completed such amajor milestone. Based on our plans and the work we have ahead of us, we planon stacking the booster section in a couple of weeks and plan to have theentire vehicle stacked in August. It will really be something to see.

More to come…

-Bob Ess