ZANL188 From United States of America, joined Oct 2006, 3248 posts, RR: 0 Posted (4 months 4 weeks 5 hours ago) and read 4648 times:
Another space commercialization idea that may or may not work out is SpaceX's Grasshopper. The idea is to fly a Falcon 9 first stage back to its launch site & reuse it, thereby lowering the cost of getting to orbit.
Recently SpaceX had another successful test of the Grasshopper, flying the 12 story tall vehicle to a height of approximately 12 stories and then landing. Amazing thing to me here, vs other similiar vehicles, is the sheer size of the thing... It's BIG, note the vehicles around the launch pad...
nomadd22 From United States of America, joined Feb 2008, 1561 posts, RR: 0 Reply 2, posted (4 months 3 weeks 6 days 14 hours ago) and read 4463 times:
I'd been wondering how they'd get the 2nd stage on the ground since an M1D would be way too powerful. It looks like 4 small thrusters. Super Dracos don't seem likely since you'd have to add hypergolic tanks.
GST From United Kingdom, joined Jun 2008, 927 posts, RR: 0 Reply 4, posted (4 months 3 weeks 6 days 9 hours ago) and read 4388 times:
Quoting zanl188 (Reply 3): 2nd stage is the difficult bit.
Whilst that is probably true on the propulsion end, I'm not sure it is on the navigational side. The second stage is inserted into orbit and can be directed to de-orbit at any time with little fuel requirement and with the considerable aerobreaking meaning relatively little fuel will be needed to steer and retard the module for the final pad landing. The first stage does not get into an orbit, therefore to get it back to the initial launch pad requires you to burn not only to decelerate but indeed to reverse direction onto a ballistic trajectory back to the pad. This needs far more fuel, even for a relatively light stage. Much better IMO to land somewhere like the Azores (or possibly even further afield) and ship the rocket back home from there, which would still offer a saving over building a new one.
Of course the remote landing pad would somewhat complicate the weather requirements for go/no go decisions if the economics of the launch operation actually require the launcher to be reusable in every instance.
zanl188 From United States of America, joined Oct 2006, 3248 posts, RR: 0 Reply 5, posted (4 months 3 weeks 6 days 9 hours ago) and read 4380 times:
Quoting GST (Reply 4): Much better IMO to land somewhere like the Azores (or possibly even further afield) and ship the rocket back home from there, which would still offer a saving over building a new one.
Quite a bit of fuel would be needed to get as far down range as the Azores. Seems to me the thing to do would be to land on a large barge, maybe an old oil tanker, or a spit of land somewhere.
The other problem with going back to the launch site is range safety. Titusville is just on the other side of the river from the launch site... would be bad to drop a first stage on the neighbors.
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GST From United Kingdom, joined Jun 2008, 927 posts, RR: 0 Reply 6, posted (4 months 3 weeks 6 days 8 hours ago) and read 4357 times:
Quoting zanl188 (Reply 5): Quite a bit of fuel would be needed to get as far down range as the Azores. Seems to me the thing to do would be to land on a large barge, maybe an old oil tanker, or a spit of land somewhere.
More fuel than reversing direction? I'm not so sure. But I agree a floating pad would seem to be the most practical first stage recovery site as you can put it wherever is most convenient. Of course if it is convenient for first stage recovery it would almost certainly be in a location that you can easily bring the second stage down onto after payload insertion too which simplifies things massively.
Quoting zanl188 (Reply 5):
The other problem with going back to the launch site is range safety. Titusville is just on the other side of the river from the launch site... would be bad to drop a first stage on the neighbors.
True, but is it any worse than a first stage going boom shortly after liftoff and raining rocket fuel on the vicinity? I'd love to see the relative risk assessments of those!
zanl188 From United States of America, joined Oct 2006, 3248 posts, RR: 0 Reply 7, posted (4 months 3 weeks 6 days 7 hours ago) and read 4350 times:
Quoting GST (Reply 6): True, but is it any worse than a first stage going boom shortly after liftoff and raining rocket fuel on the vicinity? I'd love to see the relative risk assessments of those!
Generally on liftoff the boosters are heading away from populated areas... In this case the booster is headed towards a populated area, big difference.
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nomadd22 From United States of America, joined Feb 2008, 1561 posts, RR: 0 Reply 9, posted (4 months 3 weeks 6 days 2 hours ago) and read 4249 times:
Spacex seems to be getting pretty serious about the Texas site. That would change the 1st stage recovery equation some. Texas to Florida is a whole lot more practical than Florida to the Azores. That would only be about 20% further than the 1st stage impacts now. Just a little lower trajectory could put the 1st stage right where they want it.
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