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Overall, I'm very impressed by SpaceX's efforts. However, I'm wondering why they haven't tested the Grasshopper out on a water barge? It may be no different tha

Overall, I'm very impressed by SpaceX's efforts. However, I'm wondering why they haven't tested the Grasshopper out on a water barge? It may be no different than on land, but that seems like a large assumption to make and a crucial variable to ignore.

maxerickson 12y ago
Would that save them much development effort? I would think they would have to do a lot of refit each time they dumped it in the ocean.
- whoisthemachine 12y ago
  Very good point. It may not in terms of pure time or money. But in terms of eliminating "unknowns", it will certainly save them many headaches. Generally the unknowns are what cost you in development efforts. In this case, was it the variability of a water platform (however minute) that caused the over correction, or was it a fault of a piece (i.e. valve or something similar) in the rocket? When doing something new it's much easier if you eliminate all unknown variables except for one. So first, develop a controlled rocket that can hover and land on land (grasshopper). Next develop one that can hover and land on water. Now all major unknowns are eliminated except for the big one, landing a rocket from space, on either a water platform or a land platform. However, you will now be able to discern whether the issue is related to the water platform or just the general difficulties of landing a rocket hurtling down from space.
  - maxerickson 12y ago
    Wouldn't saving either time or money (or both) be the entire point of using a specialized test vehicle? They are anyway working their way through the unknowns by trying to recover the boosters. I think they are also pricing the launches so that at least all the direct costs are covered, so these tests are 'free'.
mrfusion 12y ago
Or put a barge in a wave pool or lake to test the grasshopper. That would save on transport costs.

maxerickson 12y ago

Would that save them much development effort? I would think they would have to do a lot of refit each time they dumped it in the ocean.

whoisthemachine 12y ago
Very good point. It may not in terms of pure time or money. But in terms of eliminating "unknowns", it will certainly save them many headaches. Generally the unknowns are what cost you in development efforts. In this case, was it the variability of a water platform (however minute) that caused the over correction, or was it a fault of a piece (i.e. valve or something similar) in the rocket? When doing something new it's much easier if you eliminate all unknown variables except for one. So first, develop a controlled rocket that can hover and land on land (grasshopper). Next develop one that can hover and land on water. Now all major unknowns are eliminated except for the big one, landing a rocket from space, on either a water platform or a land platform. However, you will now be able to discern whether the issue is related to the water platform or just the general difficulties of landing a rocket hurtling down from space.
- maxerickson 12y ago
  Wouldn't saving either time or money (or both) be the entire point of using a specialized test vehicle? They are anyway working their way through the unknowns by trying to recover the boosters. I think they are also pricing the launches so that at least all the direct costs are covered, so these tests are 'free'.

mrfusion 12y ago

Or put a barge in a wave pool or lake to test the grasshopper. That would save on transport costs.