1. Cape Town
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    22 Dec '15 07:28
    YouTube

    SpaceX has successfully re-landed a Falcon 9 First Stage rocket booster potentially cutting millions off the cost of rocket launches.
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    22 Dec '15 08:364 edits
    Originally posted by twhitehead
    https://www.youtube.com/watch?v=1B6oiLNyKKI

    SpaceX has successfully re-landed a Falcon 9 First Stage rocket booster potentially cutting millions off the cost of rocket launches.
    even I am surprised by this! To be honest, for a moment there, I thought I was looking at a hoax for, in the video, it appears to me to land so fast with such velocity that it just looks physically unreal to me, just like in one of those stupid unrealistic scenes in one of those really stupid typical third-rate science fiction films which are not worth watching unless you want a good laugh of ridicule. I would have thought it should have crushed and blow up on landing. I think they were wise to make this an unmanned rocket and unmanned missions are the way to go for future space missions.

    Some basic info about it explained here:

    http://phys.org/news/2015-12-spacex-rocket-months-accident.html
    "...
    SpaceX sent a Falcon rocket soaring toward orbit Monday night with 11 small satellites, its first mission since an accident last summer. Then in an even more astounding feat, it landed the 15-story leftover booster back on Earth safely.

    It was the first time an unmanned rocket returned to land vertically at Cape Canaveral, Florida, and represented a tremendous success for SpaceX. The company led by billionaire Elon Musk is striving for reusability to drive launch costs down and open up space to more people..."
  3. Cape Town
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    22 Dec '15 09:562 edits
    Originally posted by humy
    I think they were wise to make this an unmanned rocket and unmanned missions are the way to go for future space missions.
    You may have misunderstood what is going on here. What landed is the main booster stage of the rocket. Even in manned missions, the booster stage would not be manned on return. Even if the landing failed it does not impact the overall mission as the part of the rocket going to space has already detached by that time. They did not choose to make this an unmanned mission. They were launching communications satellites on contract. They plan to attempt the same thing for all missions whatever the payload although I believe it may not be possible for very high altitude (geostationary orbit or beyond) missions.

    Normally the booster is allowed to burn up in the atmosphere or crash into the ocean and it generally rebuilt for each launch. It contains the main engines and constitutes a major part of the cost of each launch.
    SpaceX has been planning this for quite some time and has previously attempted to land it in the ocean (for safety as they were the first such attempts). Those failures did not result in failed launches ie the payload to be launched was launched as planned.
    YouTube


    If this strategy works well the booster would be ready to be used for another launch within days (or even hours) of its return.

    Another space company Blue Origin did something similar just one month ago, but at a much smaller scale:
    https://www.blueorigin.com/
  4. Cape Town
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    22 Dec '15 10:07
    YouTube
    Start at 20:10

    Cost of fuel and expendables: 0.3% of the cost of the mission.
    Re-usability could reduce launch costs by a factor of 100.

    I have seen a better breakdown of all the costs in another Elon Musk video but I don't recall which one.
  5. Cape Town
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    22 Dec '15 10:081 edit
    Early tests of the concept two years ago:
    YouTube
  6. Subscribersonhouse
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    22 Dec '15 12:57
    Originally posted by twhitehead
    Early tests of the concept two years ago:
    https://www.youtube.com/watch?v=9ZDkItO-0a4
    One thing you give up for this technology to work: Payload capacity. But recovery of the main booster rocket has to make everything cheaper.
  7. Cape Town
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    22 Dec '15 15:46
    Originally posted by sonhouse
    One thing you give up for this technology to work: Payload capacity.
    Why? My understanding is that the only limit is what orbit you are going to not what your payload capacity is. Certainly for many of the missions SpaceX has been running they didn't have to reduce the payload capacity to include this feature.
  8. Cape Town
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    22 Dec '15 15:55
    Sources vary regarding reduced payload:
    https://en.wikipedia.org/wiki/SpaceX_reusable_launch_system_development_program#Economic_issues
    Wikipedia says around a 30 percent reduction of the maximum payload

    This article:
    http://www.popularmechanics.com/space/rockets/a7446/elon-musk-on-spacexs-reusable-rocket-plans-6653023/
    says 40 percent reduction.

    But given the massive cost savings it is worth it.

    The sources also say that recovering the second stage is also planned.
  9. Subscribersonhouse
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    22 Dec '15 18:22
    Originally posted by twhitehead
    Sources vary regarding reduced payload:
    https://en.wikipedia.org/wiki/SpaceX_reusable_launch_system_development_program#Economic_issues
    Wikipedia says around a 30 percent reduction of the maximum payload

    This article:
    http://www.popularmechanics.com/space/rockets/a7446/elon-musk-on-spacexs-reusable-rocket-plans-6653023/
    says 40 percent reduction. ...[text shortened]... avings it is worth it.

    The sources also say that recovering the second stage is also planned.
    Here is one real possibility for propulsion: Microwave from ground level to provide power for launch:

    http://blogs.discovermagazine.com/d-brief/2015/07/22/microwaves-could-power-tomorrows-space-shuttles/#.VnmV5vkrKUk

    Don't know if you can get a beam to be concentrated to the size of a spacecraft but if they can, and get microwaves powerful enough it is usable.
  10. Cape Town
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    22 Dec '15 20:22
    Originally posted by sonhouse
    Here is one real possibility for propulsion: Microwave from ground level to provide power for launch:

    http://blogs.discovermagazine.com/d-brief/2015/07/22/microwaves-could-power-tomorrows-space-shuttles/#.VnmV5vkrKUk

    Don't know if you can get a beam to be concentrated to the size of a spacecraft but if they can, and get microwaves powerful enough it is usable.
    Nice idea although I foresee the military stealing it for taking out satellites.
  11. Subscribersonhouse
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    23 Dec '15 14:011 edit
    Originally posted by twhitehead
    Nice idea although I foresee the military stealing it for taking out satellites.
    Technology is ALWAYS a two edged sword. You could also use those megawatts of energy to crash fighter jets in combat too. But I wonder if enough power can be concentrated on a craft to actually lift it off the ground. My guess is the first generation would be a hybrid, smaller rocket than usual adding some lift but not enough to get off the ground augmented by megawatts of RF and between the two, the craft launches.

    Later generations would probably have enough RF energy to launch with no augmentation rocket.

    Also, the higher frequency you use the smaller the dish you need to get the proper focus at X distance.

    But the higher frequency you use, the harder it is to generate high RF power, technologically speaking.

    I bet they would love to use 100 ghz but try getting 100 megawatts at that frequency.

    1 ghz, it would obviously be a lot easier, but the wavelength of 1 Ghz is 330 mm so you would need a really large dish to concentrate 100 megawatts at say, 100 miles up.

    100 Ghz has a wavelength of about 3 mm or an area of about 7 mm^2 so you can see a dish of 70 mm^2 would concentrate 10 complete wavelengths at that frequency but at 1 ghz, the wave would occupy about 85,000 mm^2 so to concentrate 10 wavelengths would require 850,000 mm^2 or a dish of 500 odd mm diameter verses 10 wavelengths at 100 Ghz needing a dish of only 5 mm diameter.

    Of course the real dishes would be many times bigger but you see the ratio involved.
  12. Cape Town
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    18 Jan '16 07:22
    Another attempt at landing first stage coming up in the next 20 mins:
    YouTube
  13. Cape Town
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    18 Jan '16 08:01
    I got the timing wrong. It took place yesterday. The first stage did land on the ship but fell over and exploded.

    The actual launch was successful ie the satellite is in orbit.
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    18 Jan '16 08:293 edits
    Originally posted by twhitehead
    I got the timing wrong. It took place yesterday. The first stage did land on the ship but fell over and exploded.

    The actual launch was successful ie the satellite is in orbit.
    as I understand it, it fell over only because one of its legs broke on landing.
    I think they should analyze exactly how that happened (to the best of their ability) and then see if they can make just a relatively small alteration (try to make it 'small' if possible to keep research costs down) to the leg design so that it wont happen again to their next rocket landing; -although I guess they must have already thought of doing all that next else they wouldn't be too smart!
  15. Cape Town
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    18 Jan '16 11:13
    Originally posted by humy
    -although I guess they must have already thought of doing all that next else they wouldn't be too smart!
    Yeah and its not the first failed landing either and they do learn as they go along. I certainly expect we will see a first stage successfully landed and re-used in the next couple of years saving 30 million dollars or so.
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