Nh - The Launch Thread, Godspeed little one Options

[djellison]

I thought it was time, with the Atlas V about to roll out - for a new thread for NH for the launch etc.

Someone asked over at the HZ just how NH can go so fast, this was my reply....

How do you get a spacecraft to Jupiter in under a year? Easy. Make it very very light, and put it on a very very big rocket. The config of Atlas V rocket being used to launch NH (551 - 5m fairing, 5 solids, and one engine on the Centaur stage ) would typically put 8,670kg into GTO or 20,520 into LEO.
New Horizons is 478kg, and it's Star 48B 3rd stage is 2,137kg - so instead of hauling 20 tons, this vehicle is hauling about 2.5 tons thus you get a HUGE velocity out of it. AND, once it's done that, you have the final kick of the 48B, 591 thousand kgs-s (thus accelerating is all a further 3.5 - 4km/s ball park speed, if my maths is right)
At launch - the vehicle is 573,160kg. NH is 0.083% of it.
Imagine the Apollo entry capsule on top of a Saturn V...tiny tiny tiny... that was 5,800 kg on a 3,038,500kg rocket - 0.191% - more than double that percentage of NH. The cutaway's are almost comical, with this tiny gold-clad box on an enormous vehicle.
Basically - it's a LOT of rocket, and not a lot of payload.
For comparison, look how much fuss was made of Stardust that entered so quickly. It took >16 hrs to get from the distance of the moon to Utah. NH makes that journey in 9 hours
One thing the NH mission is not short of, is superlatives.

I'm not one for good luck charms (although I'll eat peanuts during a Martian EDL with the best of them), but this mission has been so long in coming, that it deserves every ounce of luck it can have - the best, most accurate launch possible, the cleanest checkout, and incident free cruise to Jupiter.

Goodluck and Godspeed little one, we're with you every step of the way.

Doug
PS - Alan, you're a credit to your field, spending so much time answering questions and writing the PI Perspectives, it's been a hell of a journey!

[edstrick]

Uh....

Would somebody explain to me how they have 3 solid rocket strapons on one side of the booster and 2 on the other side.. and not have the launch vehicle go "TILT" during flight?.. I think they're firing all 5 at the same time... I'd assumed a evenly spaced "star" pattern for the strapons, but they don't have'm that way.

[ugordan]

Would somebody explain to me how they have 3 solid rocket strapons on one side of the booster and 2 on the other side.. and not have the launch vehicle go "TILT" during flight?.. I think they're firing all 5 at the same time...  I'd assumed a evenly spaced "star" pattern for the strapons, but they don't have'm that way.

It's because every booster's thrust vector is aligned to go through the center of mass of the vehicle. That way no rolling torque is induced, only sideways translation at worst (if one of the boosters under/overperforms or something, inducing translation, which can probably be perfectly well compensated for by the main engine gibals). A similar situation is present with the space shuttle, once the SRBs jettison, the 3 SSMEs need to gimbal to adjust the thrust through the new center of mass.