The Astronomy Thread

I found this to be extremely awesome. The Spacex Cast is transposed over this visualization of the velocity and trajectory of the launch. It shows the altitude/velocity of the vehicle(s) - it shows when their engines are lit. The trajectory is exactly what you might expect, but its so hard to visualize the fact that our universe is quickly all about arcs. Our daily lives are on such short distances that the world might as well be flat. This also helps put into perspective why SpaceX is doing something that Blue Origin is light years from doing. There is very little truly vertical flight in this entire process. The falling portions of stage 1 I found fascinating with the graphs. I think the deceleration before the final burn must be when the maneuvering fins interfere with its acceleration from gravity.

Near the end of the video - both the full stage 2 and stage 1 trajectories are visualized together on the graphs.

Dandain_sl said:

I found this to be extremely awesome. The Spacex Cast is transposed over this visualization of the velocity and trajectory of the launch. It shows the altitude/velocity of the vehicle(s) - it shows when their engines are lit. The trajectory is exactly what you might expect, but its so hard to visualize the fact that our universe is quickly all about arcs. Our daily lives are on such short distances that the world might as well be flat. This also helps put into perspective why SpaceX is doing something that Blue Origin is light years from doing. There is very little truly vertical flight in this entire process. The falling portions of stage 1 I found fascinating with the graphs. I think the deceleration before the final burn must be when the maneuvering fins interfere with its acceleration from gravity.

Near the end of the video - both the full stage 2 and stage 1 trajectories are visualized together on the graphs.

Click to expand...

That video is fucking awesome!

WatchinBreakthrough Starshot on Livestream

Dyson and Hawking and such talking about doing some teeny small probes with solar sails

Its a batshit insane idea...but it just might work and if so would be cool as hell. Hopefully any Centaurans don't take us firing a few hundred to thousands of iphones at 20% the speed of light in their direction as an act of hostility.

Tuco_sl said:

That's very cool and really shows why they want to be able to land at sea.

I wonder how much the sea-landing location varies based on payload?

Click to expand...

I think most of it has to do with speed, (but clearly also trajectory), the higher the orbit, the tinier the recovery area possible because as that video shows - you really are just trying to go sideways really fucking fast to stay in orbit. That's 99% of the task almost, getting to altitude is easy, going 17,000+ mph is hard. For further orbits, especially geostationary, lagrange points etc I'm sure you have to go even faster. that video also made me realize exactly how much firepower they exert to return stage 1 to land in Florida. For the barge landing they kill almost all its horizontal speed and it re-accelerates through a much more vertical free fall, to get back to the cape they have to get that thing moving horizontally substantially to fall back on land. It definitely doesn't fly more as controlled fall - it has no lift surfaces besides those airbrake/landing fin combination. They said this mission could have returned to land, but they wanted to try the barge shot since their next 3 launches cannot possibly return to land. I think when you scale it all up to the falcon heavy - that there are very few launch trajectories where the F9 Stage 1's can get back to land.

The barges just let you recover at the best possible location for any booster regardless of mission. If the barge landings become some 99% success story - that will be incredible.

edit: video turned private

Ukerric_sl said:

Laser-illuminated solar sails.

Click to expand...

100GW of ground based lasers required. As they say, "A number of hard engineering challenges remain to be solved before these missions can become a reality", and I'm sure the Chinese and Russians are going to love the idea of 100 GW of lasers that can hit small targets in orbit over a period of time to "accelerate" them.

Breakthrough Initiatives

NASA to Attach, Test First Expandable Habitat on Space Station | NASA

TLDR; You can watch the installation.

Running Dog_sl said:

100GW of ground based lasers required. As they say, "A number of hard engineering challenges remain to be solved before these missions can become a reality", and I'm sure the Chinese and Russians are going to love the idea of 100 GW of lasers that can hit small targets in orbit over a period of time to "accelerate" them.

Breakthrough Initiatives

Click to expand...

They probably wont' care, the current plan they have will only fire off about one per day. Lasers have two ways to increase their power, you either increase the power source and all the hardware to support it like cooling etc or you can do beam additions. Their plan is to do the beam additions where they keep adding in more and more laser pulses to the same beam until it reaches a power level they want over the specific time period. This limits how many they can fire a day with their current plan to 1, which is not exactly a weapons technology.

Some point in the near future (10 years maybe?) when we start building large solar arrays in orbit we'll probably have one powerful enough to keep the laser going indefinitely and there is nothing to say you can't turn that around and fire it at earth as weapon.

the lunar module had very thin walls too