posted 03-31-2008 01:05 PM               

NASA to Brief Media About Ares I Rocket Vibration Report

NASA will host a media teleconference on Thursday, April 3, at 2:30 p.m. EDT to discuss findings from the Ares I thrust oscillation focus team. The team has been studying possible vibration concerns in the early designs of the new crew launch vehicle NASA is designing as part of the Constellation Program, which is building a spacecraft that will return humans to the moon by 2020.

The briefing participants are:

• Rick Gilbrech, associate administrator, Exploration Systems Mission Directorate, NASA Headquarters, Washington
  
• Doug Cooke, deputy associate administrator, Exploration Systems Mission Directorate, NASA Headquarters
  
• Steve Cook, manager, Ares Projects, NASA's Marshall Space Flight Center, Huntsville, Ala.
  
• Garry Lyles, associate director for technical management, NASA's Marshall Space Flight Center

The teleconference also will be audiocast live on NASA's website.

posted 04-01-2008 10:00 AM            

quote:

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Originally posted by SpaceAholic:
I think the underlying strategy at play from the deckplate level is to drag this out until Griffin is gone at which point rudder correction will be issued to reassess use of a liquid first stage alternative...

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posted 04-01-2008 08:34 PM               

quote:

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Originally posted by SpaceAholic:
This is personal for Griffin...

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posted 04-02-2008 09:59 PM               

Program to replace shuttle is in trouble

NASA's Constellation program - the successor to the aging space shuttle - faces critical problems and may never work as intended, according to a congressional report set for release Thursday.

The report by the Government Accountability Office, the investigative arm of Congress, ticks off a list of difficult issues, especially with the Ares I rocket, which it said is prone to violent shaking on liftoff and might not have enough power to reach orbit with a capsule full of astronauts.

posted 04-03-2008 01:57 AM               

• Flight Global: NASA cancels Ares I crew launch vehicle test study

• NASASpaceflight: Ares I Thrust Oscillation mitigation - the current state of play

• Wired: House Democrats Plan Attack on NASA's Mars Mission

  I like the first sentence: "Tomorrow morning, the House Committee on Science and Technology will challenge NASA's vision for space exploration."

  I thought it was the President's Vision... okay, NASA is in charge of implementing it but with the coming of a new president and an obvious lack of bipartisan support (unless the Vision is labeled as a jobs program), and after reading Thor Hogan's "Mars Wars: The Rise and Fall of the Space Exploration Initiative" (NASA SP-4410), I'm more and more skeptical about all this...

posted 04-04-2008 12:58 AM               

Well, build the rocket and test it. Apparently that's the only way to find out if there's an issue and if the proposed fixes work.

posted 04-04-2008 06:46 AM               

Ares 1 vibration worries eased

Concerns that the new Ares 1 rocket could suffer from severe vibrations have eased after new analyses have found the problem is not as severe as once thought. NASA officials said Thursday the thrust oscillation problem with the Ares 1 was not strong enough to pose a risk to crews on the Orion spacecraft that would be launched by the Ares 1. Engineers are also looking into solutions to mitigate the vibrations, including shock absorbers on the rocket or dampers under the seats inside Orion. The Ares 1 lower stage is a five-segment version of the solid rocket boosters used on the space shuttle; many solid-fuel boosters suffer from thrust oscillation problems.

Related links:

• NASA studies shock absorbers to fix moon rocket (Houston Chronicle)
  
• NASA works to end Ares' shake threat (Huntsville Times)
  
• NASA says it's close to fixing new Ares craft's flaw (Orlando Sentinel
  
• Worry on Vibration in New Rocket Has Eased, NASA Says (New York Times)

posted 04-18-2008 12:50 AM               

The Constellation Program is continuing to push through technical and monetary challenges in an attempt to protect the long term schedule.

The latest internal workings are currently being implemented into the Initial Operational Capacity (IOC) schedule, which shows the threat of delays range through the entire schedule - from the Ares I-X test flight, all the way through to NASA's return to the moon.

posted 08-11-2008 05:23 PM               

"It's a really rather elegant concept of using electromagnetic mass absorbers," he said. "Basically, what they are are big springs at the base of the rocket, either arrayed inside or outside the aft skirt of the first stage. The team has identified a concept, a system that has an active element to it to sense what's going on with the vehicle, the way it's behaving, and actually manipulate those mass absorbers to tune up with the offending oscillations. That looks to be very effective."

posted 08-19-2008 04:00 PM               

NASA Unveils Ares I Thrust Oscillation Plans

To mitigate the thrust oscillation potential on the Ares 1 rocket, engineers are looking to use a combination approach. They have proposed an active tuned mass absorber that would detect the frequency and amplitude of the thrust oscillation with accelerometers and internal pressure sensors, and use battery-powered motors to move spring mounted weights up and down to damp the vibration out. Engineers are also looking to use a passive "compliance structure" -- essentially a spring-loaded ring that would detune the stack by softening the interface between the first and upper stages while preserving lateral stability -- in the Ares 1 design concept.

posted 08-19-2008 04:03 PM               

Without any mitigation, loads as high as five or six times the force of Earth's gravity - Gs - could be experienced. With a strictly passive system, engineers believe the loads would drop to around one G. While that would not pose a health concern, it still could impair performance, causing blurry vision.

During a teleconference today, program managers said they are recommending a system that uses a combination of passive and active vibration control to ensure Orion astronauts do not experience more than about a quarter of a G in unwanted longitudinal vibration.

The system would use battery-powered motors to move the 16 100- to 150-pound weights as required. With a fully redundant control system, Lyles said, "we can lose multiple actuators and still effectively cancel the vibrations on the crew."

"In fact, it turns out we can design this system so that if we lose all active control, that is, our redundant controller goes out and we have no active control in the system, the whole system fails as a passive tuned-mass absorber and we'd still be well under the health limits on the crew," Lyles said.

The system will add weight and thus reduce the mass that can be delivered to the moon or low-Earth orbit by 1,200 to 1,400 pounds. It is not a one-to-one loss, however, because mass added to the first stage reduces the mass delivered to orbit by about one tenth.

In any case, managers already were holding about 8,000 pounds of performance margin in reserve to handle unexpected problems like the vibration issue.

posted 11-22-2008 03:39 PM               

I told him that I thought it was a bad idea -- SRBs are demonstrably difficult to control. But he said that after so many years of working with SRB, he's pretty confident that we've got a handle on it.

posted 02-09-2009 12:28 PM               

quote:

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Originally posted by hlbjr:
How do you fix this one?

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posted 02-09-2009 07:44 PM               

quote:

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Originally posted by fabfivefreddy:
Will this give us a fireworks display as big as the Saturn V?

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Saturn V = 7,6 million lbs thrust
Ares V = 11.4 million lbs thrust

I can't remember if this was an engineer's posting, or that of a wishful thinking fan of Ares.

posted 03-11-2009 12:47 PM               

NASA's Ares I Rocket First Stage Igniter Successfully Tested

NASA has completed a successful test firing of the igniter that will be used to start the Ares I rocket first stage motor.

The March 10 test paves the way for the initial ground test of the Ares I first stage later this year. Ares I is the first launch vehicle in NASA's Constellation Program family of space vehicles that will transport astronauts and cargo to the International Space Station, the moon and beyond in coming decades.

"This successful test represents a milestone in our continuing development of the Ares I first stage," said Alex Priskos, first stage manager for the Ares Projects at NASA's Marshall Space Flight Center in Huntsville, Ala. "We continue to design a robust propulsion system that will provide a safe and reliable means of transportation for NASA's future missions of exploration."

The test, conducted at ATK Launch Systems test facilities near Promontory, Utah, generated a flame almost 200 feet in length. Initial data showed the igniter performed as expected. ATK Launch Systems, a division of Alliant Techsystems of Brigham City, Utah, is the prime contractor for the Ares I first stage.

The Ares I igniter is an enhanced version of the flight-proven igniter used in the space shuttle's solid rocket boosters. The igniter takes advantage of upgraded liner and insulation materials that have improved thermal properties which protect the igniter's case from the burning solid propellant.

The new igniter is approximately 18 inches in diameter and 36 inches long. It is a small, high-burn-rate solid rocket motor that is secured in the forward segment of a five-segment booster. Once the command is sent to the igniter, a sequence begins that sends a flame down the core of the 142-foot solid rocket motor. In less than a second, the booster generates more than 3.5 million pounds of thrust, triggering liftoff of the rocket.

The Ares I rocket is an in-line, two-stage rocket topped by the Orion crew capsule; its service module and a launch abort system. The first Ares I test flight, called Ares I-X, is scheduled for later this year. The first crewed flight of Orion is planned for 2015, with the first lunar excursion scheduled for 2020.

NASA's Constellation Program, which is building the spacecraft that will return us to the moon, includes the Ares I rocket, the Ares V heavy cargo launch vehicle, the Orion crew capsule and the Altair lunar lander. Marshall manages the Ares Projects.

posted 07-24-2009 01:11 PM               

NASA Unveils Ares I Thrust Oscillation Plans

Orlando Sentinel: Ares I thrust oscillation problems continue  

And there's word from Marshall Space Flight Center, where Ares I is being designed, that engineers there are continuing to wrestle with the issue of "thrust oscillation." A blog post by Dan Kanigan, a public information officer at Marshall, explains the problem this way:  

"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."

posted 07-24-2009 01:14 PM               

Orlando Sentinel: Report: No escape system could save astronauts if Ares I rocket exploded during first minute

The crew of NASA's newest spacecraft "will not survive" an explosion of the Ares I rocket within the first minute of launch because blazing chunks of solid-rocket fuel would melt the parachutes on the crew-escape system, according to a new Air Force report.

The report by the 45th Space Wing at Patrick Air Force Base -- which has safety responsibility for the Cape Canaveral rocket range -- used data from an unmanned Titan IV that was blown up by safety officers when its guidance system malfunctioned soon after leaving the pad at Cape Canaveral in 1998. Like Ares I, the Titan used solid-fuel motors.