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SpaceX's Falcon 9 Crashes Into Droneship (cbsnews.com)
SpaceX failed to successfully land its Falcon 9 on a drone ship at sea on Wednesday. Prior to today's crash, the company was able to conduct three successful experimental landing of its used rocket in a row. SpaceX founder Elon Musk noted that the booster rocket had a RUD (rapid unscheduled disassembly, he explained) on droneship. From a CBS News report: It was the California rocket company's fifth unsuccessful drone-ship landing after three straight successes, one in April and two in May. Including a successful landing at the Cape Canaveral Air Force Station last December, SpaceX's recovery record now stands at four successes in nine attempts. But the landing attempt was a strictly secondary objective. The mission's primary goal, the launch of two powerful all-electric communications satellites, was a complete success and regardless of the loss of the first stage, company engineers expected to collect valuable data as they continue their push to make such landings routine.
I like that....
This is still lots better than what NASA is doing. Stressing the technology. Doing new things.
Going ka boom. Everybody needs an earth shattering kaboom now and again. I just wish they'd have audio on the drone ship.
Faster! Faster! Faster would be better!
Musk tweeted:
"Looks like thrust was low on 1 of 3 landing engines. High g landings v sensitive to all engines operating at max."
"Upgrades underway to enable rocket to compensate for a thrust shortfall on one of the three landing engines. Probably get there end of year."
Landing video froze at the last moment but it looked like a bulls-eye landing. There was flame climbing up the side of the stage. Telemetry should be helpful in making improvements.
The majority of satellites use chemical rockets for orbit changes and station keeping. When the relatively small amount of propellant is used up, so is the satellite (even if it is otherwise still functional). Using ion propulsion instead could increase the life of satellites, which reduces costs.
ion propulsion is NOT "all electric". Still need some particles to ionize.
Also, chemical propellant is "heavy", meaning it takes much more mass to get an equivalent kick. If you want real words, the Isp (specific impulse) is lower for chemical propellant engines than for ion engines. With all electric satellites, you can carry much less propellant, meaning you can have a satellite of comparable capability in much less mass. In the case of these two satellites, the Boeing BSS-702SP platform they're built on means you can fit two on a "normal" GTO launch. That basically halves your launch costs.
The tradeoffs are that while all electric propulsion is very "fuel efficient", the thrust of ion engines is a very small fraction of that of the more conventional chemical propellant engines, so instead of taking days to settle in to your final orbit, it can take weeks of slow orbit raising. This is a "cost" that may or may not be worth the trade. Also, since the 702SP satellites are launched in pairs, a launch failure could take out two birds with one... rocket. To give a bit of insurance against this, Eutelsat and ABS chose to split two rockets. They'd each fly one satellite per launch, meaning they only risked one of their two each flight in case of a Very Bad Day.
Technically earlier satellites do in fact use internal combustion engines, since a rocket motor (including the chemical thrusters used for satellite manoeuvring) is classed as an internal combustion engine. Coal, I'm not so sure about as far as satellites are concerned. However hybrid rocket motors using coal as the solid fuel have been tested in the past. A quick search reveals for example this article, if you scroll down to "Pioneers", we have
"In Germany from 1937-1939, I.G. Farben ran tests using coal and gaseous NOX, which developed 10,000N for 120 sec. Hans Oberth also tested a LOX and tar-wood-saltpetre mixture.
The first US tests were conducted from 1938 to 1941 by the Californian Rocket Society using coal and GOX. In 1947, the Pacific Rocket Society tested wood and LOX motors.".
So not only coal but wood-powered rocket motors have existed.
RUD = "Rapid Unplanned Disassembly" has been around a _lot_ longer than ksp.
See google books for one example from 1991, but it goes back much further than that.
"Also lithobreaking is used as a term for crashing."
No, that refers to a type of prison labor. You mean lithobraking.
Save the RTGs for the deep-space missions. There's plenty of solar energy in Earth orbit to power satellites (solar flux is nearly 2x what it is on the Earth's surface without an atmosphere to scatter and absorb sunlight, and the high launch costs mean you can afford the expensive high-efficiency panels). Batteries (to power the satellite during the 45 minutes it's in the Earth's shadow) can operate for a decade or more, which is about the time you start thinking of replacing the satellite anyway due to its technology being outdated.
SpaceX is doing many of these things under contract to NASA *using NASA funding*
SpaceX has had six launches in 2016 so far and only one of them had any relationship to NASA as far as I can tell (a supply mission to the ISS). The rest were private launch contracts. NASA is a customer of SpaceX and has helped them a lot but if you look at the launches SpaceX has scheduled, relatively few of them are NASA funded.
Ion propulsion is heavy too. While the ISP is very impressive - ISP isn't everything, except to armchair engineers. T/W matters too, and for electric T/W isn't all that impressive... and unlike chemical engines, there's very little benefit gained as fuel is exausted as the mass of the fuel is such a small fraction of total powerplant mass. There's a reason why electric propulsion has only found niche applications.
At the cost of requiring four to six months (as opposed to four to six days) for the satellite to reach it's station on orbit. (TANSTAAFL.) It's also worth noting that this is only possible because during orbital transfer, the communications systems that are the reason for the satellites existence are turned off - making their substantial power supply available for the electric engines.
But it is electrically powered rather than by chemical reactions.
So I think it's still a pretty good description.