SpaceX Tuesday...
Discussion
That might be enough - depending on the weight of the object they want to land on the moon, its payload and its fuel load.
I still think that this "Direct Ascent" approach is not the most efficient way of getting stuff down onto the lunar surface, back up again and (eventually) home to earth.
I still think that this "Direct Ascent" approach is not the most efficient way of getting stuff down onto the lunar surface, back up again and (eventually) home to earth.
Eric Mc said:
NASA rejected that idea in 1961 as the booster needed to launch the whole assembly off the earth needed to be absolutely enormous (12 million pounds of thrust or so on lift off). Is SpaceX designing a booster with that sort of launch capability?
Starship will get refueled in orbit and be able to get to and land on the moon afikBut the 2 year plan I think is using dragon 2 which can land and take off using the superdraco's
But tbh both this and NASA plans are pipe dreams.
Eric Mc said:
That might be enough - depending on the weight of the object they want to land on the moon, its payload and its fuel load.
I still think that this "Direct Ascent" approach is not the most efficient way of getting stuff down onto the lunar surface, back up again and (eventually) home to earth.
The Apollo missions relied on the concept of the bare minimum to get the job done.I still think that this "Direct Ascent" approach is not the most efficient way of getting stuff down onto the lunar surface, back up again and (eventually) home to earth.
Musk is looking more towards the economics, lots of staging is more efficient in terms of mass, but much more costly as you have to drop stuff and leave it.
Musk's philosophy is more fuel + more reusability = cheaper.
CRS-18 live in 13 hrs https://www.youtube.com/watch?v=2Wa3EDUuP5I
annodomini2 said:
The Apollo missions relied on the concept of the bare minimum to get the job done.
Musk is looking more towards the economics, lots of staging is more efficient in terms of mass, but much more costly as you have to drop stuff and leave it.
Musk's philosophy is more fuel + more reusability = cheaper.
Recovering the 1st stage (which we now know is entirely feasible) would work well with a modern equivalent of a Saturn V.Musk is looking more towards the economics, lots of staging is more efficient in terms of mass, but much more costly as you have to drop stuff and leave it.
Musk's philosophy is more fuel + more reusability = cheaper.
MartG said:
CRS-18 live in 13 hrs https://www.youtube.com/watch?v=2Wa3EDUuP5I
Wondering if we will be able the see the Dragon pass overhead after launch in the UK as we did a while back? We have an ISS pass almost directly overhead this evening at 23:36 BST, CRS-18 launch at 23:24 BST, presumably with a matching inclination?
No idea whether CRS-18 would be high enough still to be sunlit though....and it'll probably raining cats and dogs anyway....
Eric Mc said:
When is the CRS due to arrive at the ISS?
I think it takes a couple of days in ISS Transfer Orbit to reach the station.I did, however, try and answer my own question above re Dragon visibility....and computer says No for south west England (booo!), but Yes for south west Ireland (yay!)....possibly.
Finding some preliminary TLE orbital parameters for tonights 22:24UTC launch from here, and then plugging it into some PyEphem code here, and then trying various locations it looks like CRS-18 should be visible in the south of Ireland west of Cork, about 20 minutes after launch.
East of that the Dragon at about ~200km altitude is eclipsed by the Earth - the ISS being at about 420km stays out of Earth's shadow for longer.
Predictably though, the https://www.met.ie forecast for tonight has a variety of cloudy, very cloudy, rainy, very rainy and lightning bolt graphics for south west Ireland.
The PyEphem code seems accurate - running it with the latest ISS TLE gives the same pass results as the usual ISS predictor websites.
Edited: Looks like there will be a lot of visible ISS passes in the next week though, and so as CRS-18 closes in on the ISS it might be visible in proximity to the ISS.
Edited by eharding on Wednesday 24th July 14:12
Well, the nice chap at SatTrackCam in the Netherlands has yet to post any TLE numbers for tonight's CRS-18 attempt, so I had a go at brewing my own based on his two previous calculations.
FWIW here is the woo....first the two published unofficial TLEs, then my attempt.
You'll note the only things which change are the Epoch and the Right Ascension of Ascending Node numbers (plus the checksums) - the original author seems to be using the launch time plus 1450 seconds for the Epoch, so that's just a date formatting exercise to generate the weird TLE format. My naive assumption is that the RAAN will reduce in the same proportion as the time difference between the first two attempts, and adding some checksum calculations arrive at the third set of numbers.
Of course, it might all be cobblers, but plugging that third TLE into the visibility code, I reckon the ascending CRS-18 should now be visible in Cornwall west of somewhere between Liskeard and Bodmin.
Which is nice.
Still no good for me though, so fingers crossed for another abort, and maybe see it tomorrow....
Edited - of course, that visibility figure is based on whether the target is eclipsed at the zenith, so it might be possible to see it further east as it climbs. We'll see (or, based on the weather forecast, probably not)
FWIW here is the woo....first the two published unofficial TLEs, then my attempt.
# 2019-07-21 23:35 UTC
DRAGON CRS-18
1 70000U 19999A 19202.99942255 -.00003589 11345-4 00000+0 0 09
2 70000 51.6437 188.7285 0114760 48.6187 62.8495 15.97921108 04
# 2019-07-24 22:24 UTC
DRAGON CRS-18
1 70000U 19999A 19205.95011699 -.00003589 11345-4 00000+0 0 07
2 70000 51.6437 173.8868 0114760 48.6187 62.8495 15.97921108 06
# 2019-07-25 22:01 UTC
DRAGON CRS-18
1 70000U 19999A 19206.93414351 -.00003589 11345-4 00000+0 0 08
2 70000 51.6437 168.9372 0114760 48.6187 62.8495 15.97921108 01
You'll note the only things which change are the Epoch and the Right Ascension of Ascending Node numbers (plus the checksums) - the original author seems to be using the launch time plus 1450 seconds for the Epoch, so that's just a date formatting exercise to generate the weird TLE format. My naive assumption is that the RAAN will reduce in the same proportion as the time difference between the first two attempts, and adding some checksum calculations arrive at the third set of numbers.
Of course, it might all be cobblers, but plugging that third TLE into the visibility code, I reckon the ascending CRS-18 should now be visible in Cornwall west of somewhere between Liskeard and Bodmin.
Which is nice.
Still no good for me though, so fingers crossed for another abort, and maybe see it tomorrow....
Edited - of course, that visibility figure is based on whether the target is eclipsed at the zenith, so it might be possible to see it further east as it climbs. We'll see (or, based on the weather forecast, probably not)
Edited by eharding on Thursday 25th July 12:28
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