New answers tagged

35

In my experience, I've noticed that SpaceX uses a lot of temporary components until such temporary components need to actually be tested. Since the legs of MK1, MK2, and most probably MK3 will never see uneven soils rather than concrete landing pads, they will most likely just have simple legs. After a few successes with MK3, we should start seeing much more ...


12

Quick answer is all I have time for now -- if someone wants to do a more detailed and referenced answer, please feel free and I'll delete this: While it's very big, its mass is not that high, and gravity is low. On Mars, for instance, it needs about 150 tons of fuel, plus 100 or so tons of vehicle (mass) to get back to orbit. Under Mars gravity thats only ...


2

Modern digital encoding/decoding generally introduces a level of delay Um, you mean modern digital encoding/decoding introduces error coding that allows us to use channels that are way too bad for analog comms? and the potential of packet loss. Um, you mean if even then the SNR is too bad, it might happen that we lose data, but not as much as for the ...


0

The steps are summarised as follows curl $url 2&>1 | awk -F ',' '{if(NF==12) print \$1, \$3, \$4, \$5}' | tail -n +2 Redirect it to a file. This will get you the Time, Px_J2000, Py_J2000, Pz_J2000. Now, you need to get the J2000_To_IAU Matrix somehow and then get Time, Px_IAU, Py_IAU, Pz_IAU. Get the sidereal angle at some epoch. Convert it to MCMF (...


2

It’s not a “generally accepted conclusion”, but it’s somewhat likely to be the case. The reason I have heard from people who were involved in South Pole rover prototypes is as follows: because of the constant, low temperature of the Permanently Shaded Regions, there may not have ever been enough thermal cycling for the surface sediment to settle and compact....


-1

In this answer on Physics stackexchange it is stated that a total of 368 compressor stations along the pipe line should be installed in the case of real gas transport with a given flow velocity of < 10 m/sec. The pressure drop between the compressors would be from 1 bar to about 0,4 bar.


1

You could also put it this way: The secret insight of the US was to use the following procedure: Be the richest country in the world. Over an 8 year period, spend an amount equal to 4% of your GDP as of the year you started working. The recent missions that didn't make it were operating on much lower budgets. The technological improvements were what ...


8

Some Apollo Lunar Sample Rock Containers (ALSRC) have been to the Moon twice according to the Catalog of Apollo Lunar Surface Geological Sampling Tools and Containers: Serial number 1006: Apollo 14 and Apollo 17 Serial number 1007: Apollo 14 and Apollo 17 Serial number 1009: Apollo 12 and Apollo 16 I didn't spot other items being re-used; for example, the ...


7

"Technology (satellites, computer, ML) has come a long way during this time" That may be true, but there's so much you can take with you! These modern rockets are nowhere close to the lifting capacity the Americans used. Which means you can't do the landing, stabilizing with so much brute force to keep your vehicle steady. The less weight is available to ...


11

Pipelines two orders of magnitude shorter on Earth are usually divided into many compressor stations. But let's take a look at how feasible it is. At the very least, a compressor station would have to provide a pressure greater than the pressure at the bottom of the pipeline. Fortunately, the pressure calculation needed is unusually simple for a CR3BP ( ...


84

Does the US have some secret insight into landing on the moon? Yes: fail early and often. The US developed experience with uncrewed landings first, before attempting crewed landings in the Apollo program; those earlier programs had a very high failure rate. The first US lunar spacecraft were in the Ranger program, which was simply attempting to hit the ...


35

While engineering and available technologies have greatly advanced since the 50's and 60's, safely landing something on the moon is still a highly technical feat with a critically long list of potential failure points. After a quick look at a list of moon missions, it appears that the US alone has had more launch failures than India and Israel's combined ...


5

Yes, we have found evidence for carbonaceous chondrites on the Moon. Apollo 15 and 17 both brought back samples of lunar rock that had hydrogen inclusions with an isotopic ratio that exactly matches that of the water in carbonaceous chondrites. See the cite below for details. Hydrogen Isotopes in Lunar Volcanic Glasses and Melt Inclusions Reveal a ...


3

I haven't used it myself, so I don't know what the track record is like, but this one seems pretty all inclusive: http://www.spacecalendar.com/


6

I use this from SpaceFlightNow: https://spaceflightnow.com/launch-schedule/ For launches since it tracks them pretty far out


3

Here is another take at estimating the brightness of the city lights as seen from the moon. As a starting point, let us try to estimate how much light is produced by the entire United States at night. (I would guess that this probably accounts for a significant percentage of the total light produced on Earth, and probably actually a majority of the total ...


34

It appears the answer is "no". Apollo mission reports describe night-time lights from Earth orbit, but sightings at lunar distances are notably absent. For example, The sights in earth orbit were spectacular; even on the dark side, where thunderstorms and fires in Africa captured the crew's attention. The earth-orbit timeline provided sufficient time ...


4

An independent calculation. From the ISS, Venus is as bright as the city of Valencia at night. (Other ISS views of Venus had places on Earth that I didn't recognize.) Valencia's metropolis has about 2M people. In the 1970's Earth's biggest megacity, greater Tokyo, had about 23M people. 11.5 times as many, so 11.5 times brighter. (Maybe less because ...


3

Not the same kind of geothermal but - Ground source heat pumps, aka geothermal heat pumps could have potential uses for heating and cooling of habitat buildings. These things use the ground as a heat sink and heat source. They are also reversible so that cooling of buildings adds heat to rock and earth around the pipework, which can later be recovered (with ...


10

Beyond LEO, once you're a few Earth radii away, far enough to see the entire planet, its nightside is a featureless black, at least to conventional cameras, in every one of the dozens of photos at http://www.planetary.org/explore/space-topics/earth/pics-of-earth-by-planetary-spacecraft.html, even the ones that show Earth as only a slim crescent. Edit: As ...


9

I think the poster was mistaken about hydrocarbons being on The Moon. We know some planets (like Mars) and moons (like Titan) have them, but not Earth's. The Moon does have water, however. What probably threw him is how we know it has water Water (H2O), and the chemically related hydroxyl group (-OH), can also exist in forms chemically bound as hydrates ...


1

You would not need to use water! You could use the methane and other hydrocarbons that could be used. They have much lower freezing points.


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