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Two Big Rockets Launched Early Wednesday -- Then One Landed In High Seas (arstechnica.com)
Arianespace and SpaceX both launched rockets this morning between 7:25am ET (11:25 UTC) and 7:39am ET (11:39 UTC). The Ariane 5 ES rocket sent four Galileo satellites into medium Earth orbit (at an altitude of 22,922km) for the European Commission. "These satellites will form part of Europe's own global navigation system constellation," reports Ars Technica. As for SpaceX's Falcon 9 rocket, it launched from the West Cost to deliver 10 Iridium NEXT satellites into a polar orbit 625km above the Earth. Ars reports on how the launches went: Both rockets hit their instantaneous launch windows on Wednesday morning, with the Ariane 5 booster lifting off from Kourou, French Guiana under mostly sunny skies and the Falcon 9 rocket ascending from California through a thick fog layer. The upper stages of both rockets are now in their coast phases before deployment of their satellite payloads.
After the launches, attention turned toward SpaceX's attempt to recover its first stage and payload fairing. The atmosphere offshore, where the Just Read the Instructions droneship was stationed 235km away from the launch pad, had high wind shear. This means wind speeds and directions varied at different altitudes, making it a challenge to come back to the ground in a more or less straight path. This, combined with high seas, made for the "worst" conditions SpaceX has ever tried to land a rocket in, said launch commentator John Insprucker. The cameras on board didn't capture the landing clearly, but afterward SpaceX said the rocket did, in fact, make a safe landing on the droneship. Less certain was the fate of the payload fairing amid the poor weather conditions. "This is an experimental attempt; we're still learning how to catch a fairing out of the air," Insprucker said.
After the launches, attention turned toward SpaceX's attempt to recover its first stage and payload fairing. The atmosphere offshore, where the Just Read the Instructions droneship was stationed 235km away from the launch pad, had high wind shear. This means wind speeds and directions varied at different altitudes, making it a challenge to come back to the ground in a more or less straight path. This, combined with high seas, made for the "worst" conditions SpaceX has ever tried to land a rocket in, said launch commentator John Insprucker. The cameras on board didn't capture the landing clearly, but afterward SpaceX said the rocket did, in fact, make a safe landing on the droneship. Less certain was the fate of the payload fairing amid the poor weather conditions. "This is an experimental attempt; we're still learning how to catch a fairing out of the air," Insprucker said.
It sounds like SpaceX's rocket successfully launched and they managed to recover the first stage. The Fairing is suppose to be a bonus recovery but it sounds like it was too windy to do successfully. Keep in mind the first stage actually has rocket power so it has some sort of control over where it is suppose to end up. The Fairing sounds like a huge piece of metal with a parachute. Good Luck catching that in random winds.
Both the Arianne 5 first stage and the Falcon 9 first stage landed in high seas. The Arianne sank to the bottom of the ocean to become an interesting reef for fish, as is their usual procedure. The Falcon 9 landed on a barge and will probably be reused. Yesterday's Falcon 9 recovery was pretty "hot" due to its lifting the heaviest satellite (other than space stations) there is to a substationary orbit, and it's not clear there is a 10-flight life in that booster without refurbishment. I've not yeard about the expected life of the booster in today's mission, but I'd assume 10 without refurbishment.
Bruce Perens.
Ariane cost: $165-220M per launch, 16,000 kg to LEO.
Falcon 9 cost: $50M per launch (2018), 22,800 to LEO.
Taking the middle of the Ariane cost, it is $12,000 per KG to LEO. The F9 is $2200 per KG to LEO.
Actually a very good question...
LEO satellites are usually orbited low enough that they will naturally re-enter with in a few years of "unpowered" flight, such as after it's run out of fuel or is no longer controllable. So LEO orbits are generally self cleaning over time.
For orbits that are higher, the natural decay times can be quite long (as in practically not going to happen) and in such cases the usual thing is to either plan to deorbit the satellite by putting it into a highly elliptical orbit where it drags in the atmosphere at the low point and letting gravity take it's course, OR you plan a parking orbit out of the way. Such things usually take fuel and active control of the satellite so they are not always successful. Also, some orbits have natural collection points due to the gravity between say the moon and earth. These points are often the final destination of space junk as it's a low energy way to get it out of the way into a place where it will naturally stay without help, which is a good thing.
So for LEO the issue of debris is naturally correcting, though still a bit of a risk to the satellites that operate there because of the relative speed differences which can be very high for objects in different but crossing orbits. However for LEO, there are all sorts of possible orbits and directions so you can usually stay out of each other's way. Form geosynchronous orbits the relative speed differences is quite low, given that the whole point is to make the satellites all stay in one place in the sky. This stacks up a lot of hardware in a very small space though so collisions would be more slow motion train wrecks that won't create a lot of debris than quick obliteration events that generate a lot of fast moving objects.
Of course there are all sorts of highly elliptical orbits used for various types of satellites and these are usually designed to be decaying over time, with their low points being at or near LEO levels. As in most of this stuff, they have a planned way to get the used up hardware out of the way somehow.
So no, we certainly don't convert them to debris, usually, though some have been used for target practice to prove anti-satellite weapons actually can work. Such weapons have been demonstrated by multiple countries, including the USA, China and Russia/Soviet Union.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Form geosynchronous orbits the relative speed differences is quite low, given that the whole point is to make the satellites all stay in one place in the sky. This stacks up a lot of hardware in a very small space though so collisions would be more slow motion train wrecks that won't create a lot of debris than quick obliteration events that generate a lot of fast moving objects.
Only until an evil scientist sends a box of nails going in the opposite direction.
It definitely floats. It is really light and rides astonishingly high in the water for something its size. It just gets damaged.
A fairing is 5 Million dollars of mainly carbon composite. If it's a pound heavier, that's a pound you can't have for payload. This gets really important with geosynchronous transfer orbit or (worst) direct geosynchronous, where the capability is much lower than LEO. Adding weight means there will be some missions you can't carry. I guess they could have heavier fairings for when they can afford the weight, but SpaceX likes to have only one assembly line for something if at all possible. There is a complexity cost.
While the ship can be as heavy as you want.
In the end, the net recovery just might not work. We'll see.
Bruce Perens.
The extra fuel is dirt cheap compared to the cost of the booster. Estimates vary for the cost of a booster core, maybe $20-30M, but the price of that will come down anyway now that they're finalising their F9 design with Block 5. Musk has said that the cost of refurbishing Block 4 for reflight was less than half the new cost, so still definitely worth it - and Block 5 is designed to fly with minimal refurb (as little as 24 hour turnaround) so will certainly cost a lot less than that to refly. And the added capital cost of development, reuse systems like control surfaces, and recovery ships is amortised out over dozens of launches so should be minor in the long run.
Why would anyone engrave "Elbereth"?
Hmmm.... don't know enough orbital mechanics to argue but getting heavier sattelites 8 times further away seems like it might take a much larger rocket than the space-X one. So is there much to compare here?
The two rockets are very comparable. In expendable mode, the Falcon-9 has a greater payload capacity (to the same orbit) than the Ariane 5, 8.3 tons vs 7, but with reuse it is less, only 5.5 tons to GTO.
In rocketry, is is not about power, distance or energy, rather it is thrust and delta-V (change in velocity). Higher orbit means higher velocity.
You need around 10km/s to get to low-orbit, and another 2-3 for the higher Galileo orbit, similar to geosync transfer orbit. So the "8 times further" is misleading.
the cost of carrying extra fuel isn't the purchase price of the material - which is usually low compared to the per kg cost of the rest of the vehicle - but the opportunity cost of the extra weight carried, the extra structure needed to carry that weight, the large control surfaces needed to manage the higher weight, and so on all the way down to the last turtle.
This is largely meaningless. Most rocket failures happen in the early stages of a program, while the bugs are being worked out. And the Ariane 4 was a derivative of earlier rockets in the same family. So, all in all, being able to have a streak of 40 success isn't at all unexpected.
The overall success rate for the Ariane 4 has been 97.4%. The Soyuz-U has a very similar 97.3% success rate, while the Falcon 9 has a success rate of 96.6% thusfar. Now, the Falcon 9 has not have had enough launches for that rate to be particularly meaningful; it's quite possible that, after 500 launches, it will be significantly different. However, given that the majority of failures tend to occur early on, it seems likely that their rate will only get better in the future.
Either way, the reliability of the Ariane compared to the Falcon is not a significant factor at this point given that there's less than a 1% difference between them.