Monster motor breathes fire in Mississippi NASA has successfully tested the first RS-25 flight engine, destined to power the core stage of the Space Launch System (SLS). Last year, the space agency and motor contractor Aerojet Rocketdyne rattled windows around Stennis Space Center in Mississippi with a 535-second burn of a developmental RS-25, destined purely for …
They've come up with designs for an expendable version of the RS-25 - re-designed to be cheaper than the extremely reliable re-usable version proven on 135 Space Shuttle flights. But I think this latest test is using one of the mothballed original RS-25 engines combined with some new kit, as noted here:
https://en.wikipedia.org/wiki/Space_Shuttle_main_engine#2015_tests
As for these things being "workhorse engines that are among the most proven in the world" - well, maybe: certainly the original RS-25 as used on the Space Shuttle is proven in decades of service. But the USSR and now Russia have been flying the RD-107 rocket engine (in various versions) since 1957 when they were used on the R-7 ICBM, which was developed into the venerable Soyuz launcher family - still in service.
https://en.wikipedia.org/wiki/RD-107
(By the by, NASA makes one not entirely accurate claim for the RS-25 here:
http://www.nasa.gov/exploration/systems/sls/rs25-engine-powers-sls.html
"The RS-25 [...] is the first reusable rocket engine in history."
Yes it's the first re-usable rocket engine for a space launcher as far as I know; but the Me 163 interceptor aeroplane had a rocket engine which was re-usable, just so long as it didn't explode on landing.
https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet
- and there were a few planes operated right into the 1960s which also had (somewhat safer) re-usable rocket engines, including North American Aviation's mighty X-15.)
I find it interesting that the RS-25 engine No. 2059 shown here was apparently shoved onto the back of truck for the ride out to the test stand, exposed to environmental whatnot. Perhaps any protective wrapping was removed just for the lovely picture.
This is based on that typically I'd expect there'd be some QA guy running around screaming about 'Space Hardware Transportation Procedures', and threatening to red-tag it and issue a CAR. Not there's necessarily any actual requirement (as distinct from a 'Requirement') for such covering.
Disclaimer: This is more observation than criticism. I'm not criticising anyone involved in this. I think that they're doing wonderful work. They're all lovely people.. I certainly hope we can skip having everyone leaping to their defense and trying to explain to me why tarps are impossible. But I fear that it'll happen anyway... 3... 2... 1...
Other than that, a rocket engine is pretty robust.
Yep. The RS-25s in particular had to survive months of cumulative exposure to a Floridian coastal environment, which not coincidentally hosts a corrosion test center.
This is more observation than criticism.
Your disclaimer has been duly noted. However, you unwisely decided to criticize the Glorious Government of the United States of Americana, and as required by federal law, a crack cleanup team has been assembled and dispatched to take care of the matter. Please do not offer any undue and evidently pointless resistance. Have a nice day.
Yes, I'd think a "family-sized" swimming pool would be very roughly about the size of two bathtubs (assuming we shoved two family members from a 4-member family into each bathtub). Although there would likely still be extra space left in the bathtub with the kids in it, but no space left in the tub with me and the Missus in it.
Does make me wonder - what's the average volume of a family in Olympic-sized swimming pools?
Yes, I'd think a "family-sized" swimming pool would be very roughly about the size of two bathtubs (assuming we shoved two family members from a 4-member family into each bathtub). Although there would likely still be extra space left in the bathtub with the kids in it, but no space left in the tub with me and the Missus in it.
Last time I dropped the kids off at the local pool there was suddenly a lot of extra space in it
1500 gal/sec x 500 sec = 750,000 gallons pumped, then 750,000 gal / 660,000 gal/pool = 1.136 pools emptied.
Note: 1500 gal/sec x 4 engines = 6,000 gal/sec, then 660,000 gal / 6,000 gal/sec = 110 seconds to empty an Olympic-sized pool, not 60 as noted in the article.
For reference, it takes about two minutes to pump ten gallons of fresh, clean gasoline into my xB. As it's Friday, I need to pop off and see how long it takes to draw a pint...
Lots of tra-la-la about the shuttle, but how does this compare to the Saturn V boosters, and its larger brethren which were planned but never build (I'm thinking of Nova, but there were others).
Still see solid fuel as a liability, tho'...
Paris, because she's wondering what's happened to her pool...
Yes, the upgoer 5 was a REAL rocket. None of these wimpy solid rocket boosters that you light off and hope they work properly (o-rings and all that). See: http://xkcd.com/1133/
Put an assembled Saturn 5 in space, fuel it up, and you would be at Mars "real quick", you might need pretty good brakes though as you would likely keep going. The other problem is getting full Saturn 5 up in space. It would take a few launches.
Last I heard "real quick" was a couple of days, but I don't have the exact numbers here.
The real quick is still a Honman D orbit so 120 to 140 days.
Getting into low earth orbit is about half the energy requirement. Getting there in only a couple of days will require a constant acceleration on the order of 3 to 6 gees of acceleration. Face it folks this is HARD!
If you accelerate at one constant G, flip at midcourse, and decelerate at 1G, you get to Mars in a bit over 40 days.
Supposedly (have not seen the math) but 80 tons of water and the 2 grams of antimatter to turn it to hot disassociated steam would supply the necessary energy for an Apollo command module.
Edit: 2 grams of antimatter is a LOT and illustrates how much energy you need...
>Edit: 2 grams of antimatter is a LOT and illustrates how much energy you need...
Indeed. E=mc^2 where E is energy, m is mass (in this example, 0.004 Kg since the 2 grams of antimatter would react with 2 grams of normal matter) and c, the speed of light in a vacuum, is a really, really big number. All multiplied by the same really, really big number.
So, E = shitloads.
Just did a quick and dirty simplistic calculation, assuming Earth-Mars distance at 4.85x10^7 miles (apparently that's the minimum) and zero velocity at arrival and departure (I got the distance from http://www.ces.clemson.edu/ge/staff/park/Class/ENGR120/Problems/Motion/ConstantBoostSpacecraft.html).
Turns out that 10 m/s^2 will cover that distance in about two days - 6 g takes it down to about 20 hours.
However, constant acceleration for that long at that sort of rate - 6g or 1g - is definitely beyond current engineering techniques; i.e., "HARD!".
http://www.universetoday.com/14841/how-long-does-it-take-to-get-to-mars/ says a constant boost craft driven by a VASIMIR engine might reduce the Earth-Mars travel time down to 5 months (not sure exactly what that's about: Mariner 7 got to Mars in 131 days, and 5 months is about 150 days).
a constant boost craft driven by a VASIMIR engine might reduce the Earth-Mars travel time down to 5 months (not sure exactly what that's about: Mariner 7 got to Mars in 131 days, and 5 months is about 150 days).
And New Horizons (its bridge seen here) passed Mars' orbit in 78 days. It also passed Jupiter after almost exactly 1 year of flight versus the 6 years required by Galileo, and passed Saturn's orbit in 29 months versus the 6 years for Cassini.
Galileo, Cassini, and a hypothetical crewed VASIMR-equipped vessel have something in common: they're orbital missions, not flybys like New Horizons and Mariner 7. That means they need to stop at the destination, and reserve propellant to do so. Flyby probes can spend most of their propellant going faster, saving small amounts for course corrections.
The hypothetical VASIMR also has to reserve propellant for the voyage home. So, you're piling payload requirements on payload requirements while subtracting from the available propellant for the initial outbound flight.
Further, there's the point that "constant acceleration" doesn't necessarily mean "really fast." Ion engines and VASIMR have thrusts measured in milli-newtons and newtons, giving infinitesimal accelerations to the proportionally massive spacecraft. Since you're found a constant acceleration calculator, try a flight to Mars using 0.0001G, 1/10,000th of a G. A constant acceleration flight at 1/10,000th G is not much faster than a Hohmann transfer orbit by a chemical rocket, but 1/10,000th G tends to exceed the acceleration of most spacecraft with electric rockets.
The advantage of those electric rockets is the ability to greatly reduce payload fractions spent on propellant, and/or increase onboard delta-V beyond the capability of chemical rockets. Its just that sometimes utilizing that high delta-V takes a really long time, like the entire journey, because acceleration (the rate of velocity change) is so low.
Your basic space shuttle could throw about 24,000lbs into low earth orbit.
A "Coming soon" Space-X Falcon 9 is good for a little more than twice that, say 51,000lbs.
The first SLS systems should put about 70,000lbs up there.
The evolved SLS almost doubles that, to 130,000lbs (if it happens).
Saturn V: 140,000lbs.
[ To be fair, Saturn V was the product of the race to the moon, and the smarter way to accomplish what Apollo did these days would be to assemble the Lunar and Command/Service modules in orbit, possibly even with a reentry module, so you don't need the same amount of lift. ]
Saturn V payload: 118 tonnes to LEO
SLS payload: 70 tonnes initial, 130 tonnes planned (presumably to LEO)
Nova N-M1 payload: 180 tonnes to LEO (planned, cancelled)
Data from:
http://www.astronautix.com/lvs/saturnv.htm
http://www.nasa.gov/exploration/systems/sls/rs25-engine-powers-sls.html
But the comparison table here, with references
https://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems
claims:
Saturn V payload to LEO: 140 tonnes
SLS block 2 payload to LEO: 130,700 (under development)
Long March 9 payload to LEO: 130,000 (under development)
I've come across this monster proposal from the 1960s:
https://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29
Sea Dragon payload to LEO: 550 tonnes planned.
As for solid fuel motors being a liability: well, any rocket motor can blow up if something goes badly wrong. They've got better and better at making solid fuel rockets reliable as time goes by. One advantage they have over liquid fuelled rockets is the lack of complicated moving parts.
I'd not worry so much about the precise engine technology being used so much as the management of the technology when in service: the Space Shuttle Challenger was lost not because the solid fuel booster which failed was a fundamentally dangerous design, but because management failed to take steps to address the problems with the design which became apparent in operational service. More details on that in "What Do You Care What Other People Think?" by Richard Feynman.
- the bit that's worrying for the future is that the Space Shuttle Columbia was also lost due to management failing to take adequate steps to address different problems which had become apparent in the operation of the Space Shuttle, after NASA had promised to fix that class of management problems when they were identified by the investigation in the loss of Challenger.
> "I like this new RAPTURE ROCKET, it will go heavenward like it's Armageddon"
> "No, Congressman, it's called a 'RAPTOR'"
> "Yes, Yes. Now, we just need a plan to get all the Jews to Israel fast so that the end times may be unleashed and all the non-Xtians get what they deserve. Pity the Eye-Ranians gave up their nuke ideas, we will have to find some other reason to push the button..."
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