Hacker News Reader

Comment by jgmmo | Hacker News Reader

"They've kept it small. The payload weighs only about 15kg. "

Whoa... So basically that whole mission was for 30ish pounds of actual 'useful equipment' in orbit?

NASA's MAVEN payload was just 4.3 times heavier (65kg vs. 15kg) but cost 9.1 times more ($671M vs. 74M).

So NASA is still 2.1 times more expensive per kg of useful payload. And costs scale less than linearly with the payload mass, so a bigger Indian mission would have likely been even more than 2.1 times more efficient than NASA...

What makes you think there's a linear relation between payload weight and cost?

>What makes you think there's a linear relation between payload weight and cost?

...or that payload weight is correlated with scientific value.

Fuel cost increases at a square of the delta of force required. So the NASA project was actually more efficient.

No. Most of the costs are people costs as the article rightly explains, not fuel. Fuel is an extremely tiny fraction of the overall mission costs.

These are two very different missions. The ISRO mission is primarily a tech demo, and as such can tolerate greater risk. The NASA mission is focused on a specific science question, and carries several very complex instruments sufficient to answer the question.

Yes. Remember that cost per kg for a launch- just in fuel costs- is still something like five figures USD.

Weight is a tremendous source of cost savings. Compare to the Mars Science Laboratory, at 3,893 kg. They might have spent $150k in fuel costs, while we might have spent $38M.

> just in fuel costs

I think you mean 'just in rocket costs' as the fuel cost is negligible and the cost of the launch is 5 figures (dollars/kg).

For example the falcon 9 costs $12,618/kg to GTO and $4,653/kg to LEO. I don't recall the exact figure but fuel cost is a low single digit percentage of that cost.

Sorry, my mistake. I appreciate you pointing it out.

Reply on news.ycombinator.com