Looks like a 6-week delay is on the way, so it’s not impossible that Starship flies before SLS.
https://twitter.com/nasaspaceflight/status/1566146131545001989?s=21&t=21v972CHxk3-rT5jPE22JA
Starship’s next planned launch is an orbital flight? Different vehicles with different missions and different development philosophies so I don’t know how meaningful that comparison is.
Maybe Artemis doesn’t launch till next year or whatever. There are a couple of countries and an individual or two with maybe the resources to do a manned moon landing but none of them are trying very hard. Even if they did, I’d bet against them in a race to the moon with NASA. NASA is bureaucratic and conservative and subject to the whims of politicians but still much more likely to get it done than anyone else.
Ok, I’m impressed. Just the audacity to attempt this is hard to imagine.
Attempting it I totally understand and is a lot cheaper than space x attempts because his rockets are reusable even if he fails. I used to be into robotics and it is amazing what amateurs attempt to do. Amazed he succeeded though as control wise I think what he does is more difficult than space x because smaller is most likely more difficult.
ye boii clap dem asteroid cheeks
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Haha I like that NASA is now picking on random asteroids and fucking with them.
I just hope his big brother doesn’t come looking for us.
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You say that like it’s not an impressive feat.
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I’m not sure how much more there could be to it. It seems like asteroid billiards. Just looking to see how much kinetic energy they can transfer in the impact. I think you want to hit it straight on so you don’t waste energy on making it spin. Ideally you prefer a perfectly elastic collision but maybe that wouldn’t matter much and you can’t control it anyway, idk.
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need to test more on kerbal space program
There are some details here.
There is a small companion cubesat that will watch the impact from a distance. They’ve timed the impact to let Earth-based telescopes also get a decent view.
DART has a camera to see what the surface looks like and pick out a point of impact. Mass of DART= 570 kg, mass of target asteroid= 5E9 kg, impact velocity= 6100 m/s, mass of larger asteroid= ~ 25x 100x bigger. Current orbital period is 11 hr 55 min, and the orbit radius 1.18 km. They expect to shorten the period by several minutes. So they’re trying to smack it in the rear and speed it up.
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Don’t you need to slow it down to shorten the orbital period?
Yeah, it looks like they are smacking it in the face to slow it down, not the rear.
My rockets mostly never left the ground so I don’t have good intuition. Also I’m tired so I could have this wrong but
Edit: I had posted an argument that’s probably wrong and I think you have it right. Sorry. I’ll try to show why tomorrow.
Looks like they’re planning to launch Artemis I on Tuesday, but possibly will have to call it off due to a hurricane. Apparently their last launch window is Oct 2, then they are going to have to unstack the rocket for maintenance…
These images of Neptune are unreal.
fuck
Also @Trolly.
Ok, yes, that’s right. It was confusing to me because the stable orbits with a shorter period are lower orbits, where the asteroid goes faster than its initial speed.
So what I think happens is that the asteroid is slowed down by the impact, then starts to spiral down toward the larger asteroid because it is no longer going fast enough to maintain this orbit. But its speed increases as it moves closer to the bigger rock (conservation of angular momentum). The speed goes up until it is going fast enough to sustain a new stable orbit.
So we slowed it down by hitting it with DART, causing it to move into a lower orbit, where it ends up moving faster than it was before and the orbital period is shorter.
I did some calculations. The results seem reasonable.
- Expect r_2 < r_1: r_2= 1171 m, r_1= 1180 m
- Expect v_2 > v_1, v_1 < v_0: v_2= 0.17339 m/s, v_1= 0.17212 m/s, v_0= 0.17282 m/s
- Expect orbital period to decrease “several minutes”: delT= -7.5 minutes
Details
# Source for asteroid collision data: https://dart.jhuapl.edu/Mission/index.php
# I tried to fix what Discourse did to the formatting, ymmv.
M=528E9 # Mass of larger asteroid, kg
m=5E9 # Mass of target asteroid, kg
m_D=570 # Mass of DART, kg
G=6.67E-11 # Gravitational constant, N*m^2/kg^2
r_1=1.18E3 # Initial orbit radius, m
v_D= 6100 # DART impact velocity, m/s
T_1=42900 # Initial orbital period of target asteroid, s
D_target=160 m; D_larger= 780 m
# Assuming uniform circular motion,
# find initial velocity of target asteroid, m/s
v_0= 2.0*pi*r_1/T_1
# From conservation of linear momentum before and after collision,
# find v_1, the speed of the target asteroid + DART after collision.
# Expect v_1 < v_0.
v_1= (m*v_0-m_D*v_D)/(m_D+m)
# From conservation of angular momentum, mv_1r_1 = mv_2r_2 [eqn 1]
# where v_2 is the velocity of the asteroid after it spirals down from
# the initial orbit radius to a lower orbit with radius r_2. Expect the
# velocity to increase as the radius decreases, i.e. expect
# v_2 > v_1 and r_2 < r_1.
# From Newton’s 2nd law on target asteroid,
# G*(m+m_D)*M/r_1^2=(m+m_D)*v_1^2/r_1 [eqn 2].
# From equations 1 and 2,
v_2= G*M/(v_1*r_1)
r_2= G*M/v_2**2
# Again assuming uniform circular motion, find T_2 the orbital period at the
# new lower orbit.
T_2= 2*pi*r_2/v_2
delT=T_2-T_1 # Change in the orbital period of target asteroid.