SpaceX is building a ocean-landing pad to recover rockets. Interesting…I suspect that’s the short term plan until they’re confident that they can land a rocket safely.

Also in the article:

- They expect that reusable rockets will reduce launch costs by 10x, down to below $500/pound
- Elon Musk estimates that launch costs to Mars will need to come down 10,000 times to make a colony viable.
- SpaceX has 12 missions scheduled for next year that are eligible for rocket return (i.e. doesn’t use all its fuel to launch its payload into orbit), and Musk estimates an 80% chance that at least one of them has a successful rocket return demonstration.

That last point in interesting…that means that SpaceX only predicts about a 7% to 10% chance of successful return for each mission.

## 2 comments

## Barbara Krupp

October 30, 2014 at 14:31 (UTC -7) Link to this comment

The last point “that means that SpaceX only predicts about a 7% to 10% chance of successful return for each mission” is a bit simple minded and just plain wrong. A few points to consider. First, Elon stated the 80% to 90% probability was to land AND RE-FLY the Falcon 9. Second, this is a TEST never done before in history. In fact, some bright folks thought it may be impossible. Third, this is a landing of a 14 story building with a 60 foot square base (the landing legs) coming down from near space on a platform who’s size is only 300 feet by 170 feet in an ocean with currents and waves that is NOT anchored. Elon stated the probability of landing successfully on the platform is something around 50% on the very first try which I think is amazing and perhaps optimistic given all the risk points in the testing phase. And, if you know math, to calculate the probability that multiple events occur in succession you multiply the probabilities of each event. So the probability of a successful landing on a floating platform times the probability that the Falcon 9 is successfully transported (after all this is a 14 story tall rocket on a floating platform in the Atlantic ocean) times the probability that the structure and engines are in a condition to re-fly after launching a spacecraft into orbit. So 80% to 90% probability of success with all these points of failure (multiplied times others I likely missed) is just amazing!!!

## dcmckay3

October 30, 2014 at 15:45 (UTC -7) Link to this comment

Well, it’s not “simple minded and just plain wrong” since you acknowledge that “if you know math, to calculate the probability that multiple events occur in succession you multiply the probabilities of each event”. To have the probability of 1 success in 12 tries, the fact of the matter is that there is only a 7-10% chance of any one mission landing on that landing path upright (depending slightly on the assumptions you make).

If you’d have spent any time reading this blog, you’d know that there’s no bigger fan of SpaceX and Elon Musk than I. In fact, by showing how low the probability of success is (taking Mr. Musk’s own words), I give the readers an idea of how incredibly difficult this is. I myself would not be surprised at all if it takes SpaceX less than 6 tries before they can consistently land reusable rockets.

I frankly don’t understand how in the world you thought this was an attack on SpaceX, but whatever.