I am an engineer who builds with a computer. And when I see such things as this, I sometimes spend a minute or so marveling and thinking about the complexity of building and orchestrating such a launch. In fact, I really cannot comprehend how something like this can be successfully done, given how so many things could go wrong. Yes, I understand the idea of redundancy, I understand gravity, I understand that physics and chemistry goes into this, but still, the engineer in me wonders how on earth can we make all of this work together. Really, kudos to spaceX, kudos to NASA, and and kudos to those who believe in science.
SpaceX Crew Demo-1 Mission [video]
31–40 of 88 posts
Re: SpaceX Crew Demo-1 Mission [video]
#32Goosebumps when stage 1 stuck that landing. Godspeed, Ripley!
Same here. Watching rockets land from orbit will maybe never get old.
Awesome job to everyone at SpaceX! Godspeed for the rest of the mission!
Re: SpaceX Crew Demo-1 Mission [video]
#33Kudos to the entire team of SpaceX, Nasa and Ripley (dummy) for this mission. This takes a great amount of co-ordination and integration to make this complex mission successful. Living in great era of innovation and advancement in space.
Re: SpaceX Crew Demo-1 Mission [video]
#34Man this makes me miss when I was living at UCF - we'd see shuttles taking off at Kennedy space center from East Orlando
I grew up in southwest Orlando. We'd go outside during elementary school to watch the launches, we'd interrupt little league games and football games to watch the launches. Kids and parents all just found it so magical and amazing. Those solid rockets were clearly visible even 70 miles away.
I am 180+ miles South from the pad and it is visible from here! I love watching them.
Re: SpaceX Crew Demo-1 Mission [video]
#35Looks like they nailed the launch: first stage recovered and Dragon 2 separated successfully. Congratulations SpaceX! Docking with the ISS is scheduled ~27 hours from now on Sunday, March 3 at 10:55 UTC (5:55 EST). https://www.space.com/how-to-watch-spacex-crew-dragon-demo-1...
Anyone know why they choose a launch time and trajectory such that the arrival at ISS is more than a day later? It seems like you could choose to arrive at the ISS almost immediately after reaching orbital velocity if you wanted.
Re: SpaceX Crew Demo-1 Mission [video]
#36Looks like they nailed the launch: first stage recovered and Dragon 2 separated successfully. Congratulations SpaceX! Docking with the ISS is scheduled ~27 hours from now on Sunday, March 3 at 10:55 UTC (5:55 EST). https://www.space.com/how-to-watch-spacex-crew-dragon-demo-1...
Anyone know why they choose a launch time and trajectory such that the arrival at ISS is more than a day later? It seems like you could choose to arrive at the ISS almost immediately after reaching orbital velocity if you wanted.
So they have time to validate the systems are working correctly. A direct launch would leave little margin for error, especially on a test flight.
Edit: now I think more it also allows for variations in launch performance. Soyuz does a three day rendezvous as back when the system was designed the accuracy required wasn’t possible, though now they’ve planned a same-day docking.
Re: SpaceX Crew Demo-1 Mission [video]
#37I am an engineer who builds with a computer. And when I see such things as this, I sometimes spend a minute or so marveling and thinking about the complexity of building and orchestrating such a launch. In fact, I really cannot comprehend how something like this can be successfully done, given how so many things could go wrong. Yes, I understand the idea of redundancy, I understand gravity, I understand that physics…
To help you with not feeling overwhelmed - they are doing it since May 6, 2002. It has taken a lot of time, of a lot of people to get here. There was a lot of failures also, along the way.
Re: SpaceX Crew Demo-1 Mission [video]
#38Looks like they nailed the launch: first stage recovered and Dragon 2 separated successfully. Congratulations SpaceX! Docking with the ISS is scheduled ~27 hours from now on Sunday, March 3 at 10:55 UTC (5:55 EST). https://www.space.com/how-to-watch-spacex-crew-dragon-demo-1...
Anyone know why they choose a launch time and trajectory such that the arrival at ISS is more than a day later? It seems like you could choose to arrive at the ISS almost immediately after reaching orbital velocity if you wanted.
tl;dr because the ISS orbit is not equatorial, choosing the right launch time is non-trivial and solutions are only approximate.
ISS launch windows are complicated - you have to match both plane (i.e. the Earth needs to turn so that the Cape/Baikonur is under the ISS's orbit path) and phase (i.e. at the time the plane match happens, the station needs to be at the right part of its orbit for the spacecraft to meet the ISS right after launch).
A launch site crosses the plane of the ISS orbit twice a day, but the phase angle at those crossings is often quite far off of optimal - you want the ISS to be a bit behind at launch so that by the time your spacecraft gets up to the right altitude/speed it's matched up. So you have to find the minimum phase angle at launch window for a targeted several weeks or so, then have the ISS make slight orbit changes to bring the phase angle closer to optimal. Once you're up and have as low of a phase-angle difference as possibly, you then have to spend a bunch of 90-ish-minute orbits getting your position in orbit matched up to the ISS.
At fastest, you can get down to the single-digit-hours range, but that takes a good selection of launch window, a bit of a burn in advance from the ISS to tweak its phasing, tracking systems that don't waste an orbit determining where exactly you are, and no scrubs.
This article is a good example of the process (but not the physics/geometry): https://www.nasaspaceflight.com/2018/07/progress-ms-09-super...
> The long sought attempt at launching a Russian Progress resupply vehicle to the International Space Station and having it rendezvous with the orbital complex after just two and a half orbits and just under 4 hours in space is being attempted.
...
> As with the other fast track rendezvous attempts, the reboost and phasing alignment of the Space Station with the Baikonur Cosmodrome is only available for this launch day. A scrub to today’s instantaneous launch of Progress MS-09 would have resulted in the craft having to fly a two-day, 36 orbit phasing profile to the ISS on a realigned launch date later this week.
Re: SpaceX Crew Demo-1 Mission [video]
#39Looks like they nailed the launch: first stage recovered and Dragon 2 separated successfully. Congratulations SpaceX! Docking with the ISS is scheduled ~27 hours from now on Sunday, March 3 at 10:55 UTC (5:55 EST). https://www.space.com/how-to-watch-spacex-crew-dragon-demo-1...
Anyone know why they choose a launch time and trajectory such that the arrival at ISS is more than a day later? It seems like you could choose to arrive at the ISS almost immediately after reaching orbital velocity if you wanted.
They don’t reach the stations orbital velocity immediately after launch though. What they do is launch into a lower orbit behind the station. Lower orbits have a shorter orbital period, so they gradually catch up and raise their orbit as they get closer.
If the went into a ballistic trajectory directly at the station, there is a risk of debris from the launch, such as paint flecks, scraps of metal, etc hitting the station. Also a lower initial target orbit makes various abort scenarios easier. Then of course another poster has pointed out they need time to check and validate all the vehicles systems.
Generally in space it’s best to avoid doing anything in a rush if you can avoid it. In recent years the Russians moved to a 6 hour launch to rendezvous window which is pretty quick really. This is what made it possible to capture footage of the launch from the station.
Re: SpaceX Crew Demo-1 Mission [video]
#40I am an engineer who builds with a computer. And when I see such things as this, I sometimes spend a minute or so marveling and thinking about the complexity of building and orchestrating such a launch. In fact, I really cannot comprehend how something like this can be successfully done, given how so many things could go wrong. Yes, I understand the idea of redundancy, I understand gravity, I understand that physics…
Totally understand what you mean. The complexity is mind boggling. And as more and more processes become software driven, the programmer's responsibility increases manifold. It's a wonder of engineering and team work.