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The video shows the lower stage and upper stage of a Falcon 9 taking off, then landing. These two stages are shown launching a Dragon spacecraft. The Dragon s
by jlgreco 13y ago
The video shows the lower stage and upper stage of a Falcon 9 taking off, then landing. These two stages are shown launching a Dragon spacecraft. The Dragon spacecraft is shown docking with the ISS. The pressurized half of the Dragon spacecraft is then shown landing (the unpressurized trunk section, with the solar panels attached, burns up in the atmosphere (though this is not shown in the video)).
Staging is done because not doing it ("SSTO" or "single stage to orbit") is extremely hard. In fact, it has never been done before from earth. When that second stage burns, it is only accelerating the mass of itself and the Dragon spacecraft on top. Having it accelerate the mass of the lower stage as well would be massively inefficient, requiring much more fuel to be used. So much more fuel that there most likely would no be any mass left over for the Dragon spacecraft. Without staging we wouldn't be able to put things in orbit at all (today and in the past anyway), let alone reuse rockets.
- lobster_johnson 13y agoThanks. I assumed the section with the solar panels somehow retracted the panels before re-entering the atmosphere, but they skip that part, and I now see that the part re-entering is actually a bit smaller.
- jlgreco 13y agoYup, that part burns up. It's not a complete waste though. I believe at the ISS they usually pack those sorts of parts (parts that burn up that is. Other examples being the Russian "Progress" spacecraft or the ESA's ATV) full of garbage before sending them off. Intact reentry volume/mass is valuable (currently only the Soyuz and the Dragon can do that) so they just let all of their trash burn up. Here's a neat picture of the first ATV, carrying a bunch of ISS trash, burning up: http://en.wikipedia.org/wiki/File:Jules_Verne_Automated_Transfer_Vehicle_re-enters_Earth%27s_atmosphere.jpg http://en.wikipedia.org/wiki/File:Jules_Verne_Automated_Tran...