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!

[Bill Harris]

Good cut-away image, Tesheiner. That puts the spacecraft size into perspective.

Still, it seems to me that the thrust vectors from two boosters would add up to be different than three boosters and the thrust would be uneven. But, heck, I'm just a geologist and they know what they're doing, so I won't fret about it.

I saw Alan Stern on NBC news this morning, in an interview about NH. Just before the nuclear protesters...

--Bill

[ugordan]

The thrust vectors do add up differently, but as long as they go through the center of mass, no torque is exerted.

Seems like the weather report is steadily becoming less and less favorable. Currently the conditions are "mostly cloudy" (degraded from "partly cloudy") and the wind is picking up, currently at 15 km/h.

What exactly are the launch constraints concerning the wind speed?

[Toma B]

What exactly are the launch constraints concerning the wind speed?

The Atlas 5's wind limit at launch is 33 knots...that's approx. 61 km/h.

1knot=1.852 kilometers per hour