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#580
by
cscott
on 09 Feb, 2018 15:17
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Someone mentioned off-hand that the roadster, if eventually ejected by Jupiter, could indeed become an ʻOumuamua to another civilization. If they are currently at our level of technology, they'd never know -- we haven't gotten more than a blurry radar outline of ʻOumuamua. It's a little larger than a car, but it could be a space Wiinebago for all we know---and I think the radar observations left open the possibility that it was a loose aggregate of broken-apart pieces; it could be a large alien RV in the center surrounded by a cloud of debris particles that have broken off during its long long trip.
I agree that it's extremely worthwhile to image the Roadster "asteroid" so we have a better idea what something like ʻOumuamua would look like if it were an artifact of a technologically advanced alien civilization. Of course I'm sure we "know" in theory what it looks like, but doing so in practice allows us the opportunity to be surprised by unexpected features of reality.
It also establishes a baseline for future observations in years to come, and that really is an unknown: I don't think anyone knows quite what a technologically advanced artifact would look like after eons of space weathering.
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#581
by
rockets4life97
on 09 Feb, 2018 15:40
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Reporting by Lori Garver, a former deputy administrator of NASA during the Obama Adminstration, in
this opinion piece for The Hill reveals that SpaceX offered NASA a free ride of the demo launch which they turned down.
In a follow-up tweet, Lori Garver said SpaceX made the same offer to the Air Force as well.
This seems to me to put the rest the question of why SpaceX didn't launch something more valuable on the demo flight.
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#582
by
IntoTheVoid
on 09 Feb, 2018 16:29
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Can someone annotate this picture, please?
Attached is an enhanced image. We're looking into the bottom of the upper stage LOX tank. At each corner we can see four black cylindrical helium tank. There might be other helium tanks at the top and bottom of the picture, but the long aspect ratio means we can't see them. You can see there is still quite a bit of LOX left as the LOX level is close to the top of the helium tanks. Not 100% sure what the silver cylindrical object is. It might be to contain supercold helium during the filling process. It might also be close to the camera and be some kind of level sensor.
SpaceX seems to have added a vertical structure in the middle with six fins to the sides. I believe this is to help hold the LOX to the bottom of the tank during the coast phase. At the top of the vertical structure a half hemisphere of LOX can be seen.
It doesn't look very especially different to me than this picture from SES-9 two years ago. The LOX ripples on SES-9 make it harder to see, but it does look to have all of the same structures with possibly 4 baffles rather than six.
I defer to anyone who knows, but they appear pretty similar.
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#583
by
JonathanD
on 09 Feb, 2018 16:29
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This seems to me to put the rest the question of why SpaceX didn't launch something more valuable on the demo flight.
I can understand why they didn't. They probably didn't have something ready that fit the profile, and the spectrum of negative consequences for payload loss likely far outweighed the cost of a free flight.
In the end I'm glad they didn't. Spectacle or inspiration, whatever you want to call it, Starman and his ride have reignited interest in space launches in a way not seen in a very long time. Exciting times.
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#584
by
Steven Pietrobon
on 10 Feb, 2018 05:49
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I defer to anyone who knows, but they appear pretty similar.
The bottom looks quite different to me.
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#585
by
CameronD
on 12 Feb, 2018 00:04
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This seems to me to put the rest the question of why SpaceX didn't launch something more valuable on the demo flight.
I can understand why they didn't. They probably didn't have something ready that fit the profile, and the spectrum of negative consequences for payload loss likely far outweighed the cost of a free flight.
In the end I'm glad they didn't. Spectacle or inspiration, whatever you want to call it, Starman and his ride have reignited interest in space launches in a way not seen in a very long time. Exciting times.
Well... they could have launched a big Yellow School Bus. With fluffy dice.
(Where the hell is the fluffy dice? Isn't Elon into fluffy dice??)
Exciting times indeed.
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#586
by
Mongo62
on 14 Feb, 2018 02:16
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The random walk of cars and their collision probabilities with planetsOn February 6th, 2018 SpaceX launched a Tesla Roadster on a Mars crossing orbit. We perform N-body simulations to determine the fate of the object over the next several million years, under the relevant perturbations acting on the orbit. The orbital evolution is initially dominated by close encounters with the Earth. The first close encounter with the Earth will occur in 2091. The repeated encounters lead to a random walk that eventually causes close encounters with other terrestrial planets and the Sun. Long-term integrations become highly sensitive to the initial conditions after several such close encounters. By running a large ensemble of simulations with slightly perturbed initial conditions, we estimate the probability of a collision with Earth and Venus over the next one million years to be 6% and 2.5%, respectively. We estimate the dynamical lifetime of the Tesla to be a few tens of millions of years.
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#587
by
Pete
on 14 Feb, 2018 05:48
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The random walk of cars and their collision probabilities with planets
Their analysis is subject to a large number of approximations, among which they have decided that the car and PAF are all that need to be considered.
I was under the impression that the car is still attached to the second stage?
This would make a
huge difference to the derived Yarkovski effect, which is the primary orbital permutation they address.
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#588
by
speedevil
on 14 Feb, 2018 10:59
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I was under the impression that the car is still attached to the second stage?
This would make a huge difference to the derived Yarkovski effect, which is the primary orbital permutation they address.
I have mailed the author of the paper, though noticed one person commenting on this on twitter also, asking if it's likely to make a difference.
He responded saying they have tried variants, including boosting yaardovsky by 10000 times, and found little effect.
The orbit is practically dominated by gravitational interactions with planets.
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#589
by
FutureSpaceTourist
on 15 Feb, 2018 09:29
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#590
by
crandles57
on 16 Feb, 2018 15:53
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Can you imagine some future use for it?
Suppose you wanted to deflect asteroid/comet from path that collides with Earth using mass of spacecraft put on close parallel path but didn't want to lift all the mass required from Earth. Is it possible to imagine that grabbing this spacecraft whose dimensions are known might be easier to work out how to connect it firmly to your new spacecraft than looking for a suitable mass asteroid of uncertain dimensions?
Changing the orbit to intercept the asteroid seems like it would likely be a big problem: Presumably better to gather some junk and/or satellites past (or towards) end of life in Earth orbit before setting off out of Earth orbit. Therefore, doubt this potential use works, unless others think differently?
Any other potential use(s)?
(BTW, I am fine with it having no potential use.)
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#591
by
whitelancer64
on 16 Feb, 2018 16:14
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#592
by
crandles57
on 16 Feb, 2018 17:18
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Perihelion 0.98614 au
Aphelion 1.6639 au
Inclination 1.078°
Mars Inclination 1.85°
Mars Aphelion 1.666 AU
Mars Perihelion 1.382 AU
Inclination angle difference 0.772°
1.382AU * 150 million km * 2 * Pi / 360 * 0.772 = ~ 2.8 million Km is about as close as they could possibly get while the inclination stays at 1.078° to the ecliptic.
4.3 million km closest approach in Oct 2020 is not a huge amount further away and Mars is presumably not at perihelion then, so the closest they could get with this inclination in Oct 2020 would be further than 2.8 million km.
If it is this close to the minimum possible distance for that inclination, does that mean they were deliberately aiming to get it as close as possible for the inclination? Would this be good accuracy, poor accuracy or ... ?
.
Does a sideways nudge at aphelion result in a different inclination orbit or a varying inclination orbit or ...?
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#593
by
rsdavis9
on 16 Feb, 2018 17:35
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Perihelion 0.98614 au
Aphelion 1.6639 au
Inclination 1.078°
Mars Inclination 1.85°
Mars Aphelion 1.666 AU
Mars Perihelion 1.382 AU
Inclination angle difference 0.772°
1.382AU * 150 million km * 2 * Pi / 360 * 0.772 = ~ 2.8 million Km is about as close as they could possibly get while the inclination stays at 1.078° to the ecliptic.
4.3 million km closest approach in Oct 2020 is not a huge amount further away and Mars is presumably not at perihelion then, so the closest they could get with this inclination in Oct 2020 would be further than 2.8 million km.
If it is this close to the minimum possible distance for that inclination, does that mean they were deliberately aiming to get it as close as possible for the inclination? Would this be good accuracy, poor accuracy or ... ?
.
Does a sideways nudge at aphelion result in a different inclination orbit or a varying inclination orbit or ...?
A object in a inclined orbit does pass through the ecliptic at the nodes. So you have to figure out where the nodes are for both mars and roadset.
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#594
by
crandles57
on 16 Feb, 2018 18:04
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Space .... the final museum.
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#595
by
crandles57
on 16 Feb, 2018 18:49
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Perihelion 0.98614 au
Aphelion 1.6639 au
Inclination 1.078°
Mars Inclination 1.85°
Mars Aphelion 1.666 AU
Mars Perihelion 1.382 AU
Inclination angle difference 0.772°
1.382AU * 150 million km * 2 * Pi / 360 * 0.772 = ~ 2.8 million Km is about as close as they could possibly get while the inclination stays at 1.078° to the ecliptic.
4.3 million km closest approach in Oct 2020 is not a huge amount further away and Mars is presumably not at perihelion then, so the closest they could get with this inclination in Oct 2020 would be further than 2.8 million km.
If it is this close to the minimum possible distance for that inclination, does that mean they were deliberately aiming to get it as close as possible for the inclination? Would this be good accuracy, poor accuracy or ... ?
.
Does a sideways nudge at aphelion result in a different inclination orbit or a varying inclination orbit or ...?
A object in a inclined orbit does pass through the ecliptic at the nodes. So you have to figure out where the nodes are for both mars and roadset.
>A object in a inclined orbit does pass through the ecliptic at the nodes.
Yes it does, but they are clearly nowhere close at the nodes or any time until Oct 2020.
Mars Perihelions October 29, 2016 and September 16, 2018.
http://earthsky.org/sky-archive/mars-at-perihelion-in-late-octoberSo presumably next will be around August 3, 2020. So October 2020 isn't long after Mars' perihelion.
1AU of Earth is about perihelion distance so about Feb 7 for leaving Earth orbit maybe less a few days. Oct 2020 is 2.67 year. Tesla orbit 1.525 years so one orbit and 1.145 years around a 1.525 year orbit.
Don't see that gets me anywhere apart from telling me at Oct 2020 distance from sun is only a little greater than at perihelion. So calculation (1.382AU * 150 million km * 2 * Pi / 360 * 0.772 = ~ 2.8 million Km) is only a slight underestimate.
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#596
by
rsdavis9
on 16 Feb, 2018 19:27
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#597
by
CorvusCorax
on 19 Feb, 2018 07:04
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#598
by
sanman
on 21 Feb, 2018 04:40
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Knowing what we know now following the successful launch, what would have been a more meaningful payload to put on Falcon Heavy's demo flight?
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#599
by
Mader Levap
on 21 Feb, 2018 10:50
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Knowing what we know now following the successful launch, what would have been a more meaningful payload to put on Falcon Heavy's demo flight?
USAF STP-2 and bunch of secondaries.
