Rock-a-bye Rocket


Even though the rocket is now stacked and sitting on the mobile launch platform in Kennedy Space Center’s VAB, there is still a lot of testing and prep work to be done before it’s ready to roll out to the pad. Over the weekend (Aug. 29-30) the rocket underwent two days of modal testing to make sure it’s ready to stand up to the environments it’s about to find itself in.

The testing required a total of 44 accelerometers — a device that measures movement — to be installed on the flight test vehicle. And to put those on the vehicle it took more than 27,000 feet of cable.  That’s more than 5 miles!

During the testing, vibrations were mechanically introduced into the rocket by four hydraulic shakers simulating the same kind of vibrations expected during flight so the effects could be monitored.  A sway of the vehicle was then manually introduced (with a little help from Mission Manager, Bob Ess and Deputy Mission Manager Steve Davis) to create a lateral, back and forth motion so the team could measure how the rocket reacts.


Here’s a little fast-motion clip of Steve and Bob rocking the rocket (Flickr).

This part of the testing was important because it simulated the conditions the rocket could experience as it rolls out to Kennedy’s Launch Pad 39B, the wind conditions at the launch pad before it launches, and what it would experience during flight at first stage ignition. 

NASA did some similar testing years ago on the Saturn V at Kennedy Space Center in the 60s. For those tests a group of people sat up on a platform and rocked the vehicle back and forth with their sneakered feet from one side, while another group of people pulled on the rocket with ropes from the other side. The group appropriately named it the “Tennis Shoe Test.”

The completion of the Ares I-X modal testing is an important step for the mission because it clears the way for next week’s Integrated Vehicle Power Application or systems power up test, which will be the first time that all of the electrical systems, control boxes and sensors will be turned on together and powered up.

10 thoughts on “Rock-a-bye Rocket”

  1. That fast motion clip can be interpreted a lot of different ways. Wonder who enjoyed the test more, the humans or the rocket. How can anyone can fix anything on the upper stage if there are no platforms above the shuttle level?

  2. I was wondering if October 31st is still the planned test flight date. My class has been anxiously awaiting, so any news is better than 20 kids constantly asking, “Is it going to happen?”

    Eric McElroy
    Fourth Grade Teacher
    Swarthmore, PA

  3. What about the Augustine commission? As far as I understand they are leaning to abandoning Ares and choosing an alternative launcher.

  4. I am wondering how this Ares I-X can be stacked and ready for flight in October while the booster is still waiting testing in Utah. If the test goes bad then will this delay flight testing of the Ares I-X? It seems like this is being done out of sequence. Should not the solid booster be tested first and verified for flight before the booster is attached to a vehicle for flight?

  5. @ Guest #5:

    The motor they are testing in Utah is not the same motor as the one stacked on the Ares I-X rocket in Florida. NASA has lots of solid rocket motors (the 2 white boosters you see on either side of the shuttle orbiter and the orange tank are Solid Rocket Boosters) and tests them in Utah on a regular basis for the shuttle program and now we are going to be regularly testing them for the Ares program.

    @ Guest Svetlio:

    You can read more about the U.S. Human Space Flight Plans Committee here:

    https://www.nasa.gov/offices/hsf/home/index.html

    @Eric McElroy

    You’re right, October 31 is still the planned test flight launch date. We’re making great progress and things are looking good!

    @Guest #1

    There are access platforms built inside the upper stage that allow the team to get up there and do the work they need to.

  6. Where’s the video of what the pointy end of the rocket looked like during the rock-a-bye? Movement must have been measured in feet @ the 327′ level.

  7. I am at a loss to understand how a $360 million “test” flight of Ares 1-X in it’s planned configuration could have mustered approval.

    Although allegedly intended to “test” the rocket’s first stage flight control system, parachute recovery system, separation of first & second stages and establish vibration parameters, in reality it tests little more than how fast we can plow through cash.

    The Ares first stage is designed for five solid rocket motor segments. The 1-X “test” flight utilizes four actual motor segments and at enormous additional cost, a “simulated” motor segment.

    That means the fact finding “test” flight fly’s lower and slower which obviously translates too less vibration. Less speed & vibration means less data on actual flight dynamics and structural integrity. Less vibration on a simulated Orion capsule means less data on launch survivability for an eventual crew.

    Due to the simulated segment, separation will occur at a slower speed and much lower altitude, making first stage tumble and chute deployment much less representative of an actual flight.

    Testing first and second stage separation adds no value as all subsequently planned Ares flights separate on an all together different plane.

    The first stage flight control system being “tested” is essentially the same one in place for the last 128 Space Shuttle launches. You’d think we’d have a pretty good handle on how it might perform.

    There’s absolutely no testing of 1-X’s second stage flight dynamics as following separation it simply continues on a ballistic arc, crashing into the Atlantic. What can we learn from such a “test” flight?

    A very possible revelation is a vehicle with such a high slenderness ratio (14′ x 327′), twice that of a Saturn V and almost twice that of a Delta IV, may very well break apart prior to planned first stage separation (ever see high speed video of a javelin in flight?). That is if it doesn’t topple over on it’s roll-out to the pad.

    Someone really needs to re-think this.

  8. Looks like someone (the Augustine Commission)did re-think this…
    and it doesn’t bode well for Ares proponents. Have they started de-stacking activities?

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