DM-2 Test – The Big Day


Live blog of the DM-2 Test

The DM-2 test was successful with early word of no anomalies. There will be a press conference shortly.

Primary bunker safety jumper is in. The bunker is 1/2 mile away. This is the last jumper to install.

Senator Hatch, the senior Senator from Utah, has shown-up for the DM-2 test. He’s taking questions from the press. In his answers regarding the Obama Administration’s original space plan that ended NASA’s leadership role in human space flight, he feels that the President has set this nation on a course to cede leadership in human space flight.. While he’s not against private firms who can compete, he regards those firms a long way from where ATK is today. He added that he considered the the private firms’ work “primitive” compared to what NASA and ATK are doing on Ares I. Says Senator Hatch, “We ought to do what is best for the country.” It was interesting that the Utah senior Senator chose to attend today’s test and indicates his interest in seeing the ATK Ares solid motor technology play a key role in the nation’s human space program.



Everything is proceeding well.

T-40 minutes

The motor, which has 1.4 million lbs. of propellant, has been chilled to 40°F temp. The motor is expected to generate 3.6 million lbs. of thrust, with a reduction of 76,000 lbs. of thrust due to colder temperature. While the thrust will be reduced a small amount, the burn-time of the motor will increase. In the end, the total impulse of the motor will remain the same.

Just to make things challenging, the joints of this test motor, which is built from legacy Shuttle hardware, have been chilled. And flow-paths have been created to test how well the seals hold-up.

A Shuttle 4-segment SRB has 24,000 lbs of insulation. As part of trying to increase the payload mass of Ares I, ATK is trying to get the weight of the 5-segment motor to to 18,600 lbs. The DM-2 motor has 20,000 lbs. to evaluate how well the reduced and reformulated insulation works.

PBAN is being used as the motor propellant rather than HTPB, for several reasons. First, it’s the propellant used in the Shuttle SRB’s, so it’s behavior and characteristics are well understood. Additionally, using PBAN means that current motor casing hardware can be used. HTPB would require additional testing and a stronger casing.

Currently, PMBT (propellant mean bulk temperature) is 42°. In first hour of the shed being pulled-back, it’s rose 4/10 of degree and will rise 1° by time of firing.

Stan Buxton – Security Mgr at ATK Utah gave us a warning not to play with the rattle snakes.

Update: Corrected PMBT as Propellant Mean Bulk Temperature, not Propellant Main Bulk Temperature. Thanks for catching our typo.


  1. Correction-PMBT is Propellant MEAN Bulk temperature (not main)-I know, I’m being picky.
    DM-2 looked awesome! I hope all the data channels worked the way they were intended. I think this will be a good thing for ATK and America’s space program.

NASA Images Now Available On Flickr

DM-2 Press Conference