Space and Science BS Thread

https://www.youtube.com/watch?v=3SSjzdj-ONw

Set for Mar1.

 

Or maybe not…
https://arstechnica.com/space/2025/02/nasa-receives-11th-hour-reprieve-from-probationary-employee-cuts/

 

Guys,

Easy question on orbital mechanics for you.

The 2024 yr4 asteroid is in the news because of its relatively high probability of hitting the earth. There is also uncertainty about its size. In this case "size does matter" if it strikes the earth...with the smaller estimates on size meaning much less affect than if it's near the max size.

But....my question is this...does the actual size also affect the asteroids orbital trajectory? Or, as regardless of size it's mass is quite small relative to a planet, will it come in with the same trajectory regardless of the asteroid's actual mass?

 

The latter - a 100m (upper bound) asteroid mass contains roughly 7500m3 of matter. By comparison, pluto (not a planet) contains 7*10^18 m3, or 10^15 times more material (and thus gravitational influence).

 

Last I heard it was more likely to hit Luna than Terra. #RingDahak’sBell so we should get some more seismic data from it. Or at least more than we got from crashing LEM’s into it which it just so happens made it ring like a bell.

 

Everything I’ve read speaks to an objects mass as being the determinant in trajectories.. I think size might play a role when encountering a gas environment due to drag

 

I thought this was an interesting question so I spent a few minutes on ChatGPT. The short answer is mass doesn't have any impact on its orbit, but when the asteroid hits the earth a larger mass is more likely to hit the ground. According to NASA the object is between 130 and 300 feet in diameter. A 130 foot asteroid would release the equivalent of 171,000 Hiroshima bombs. A 300 foot asteroid would be like 3.36 million Hiroshima bombs.

 

I think density would be a large factor considering the difference between 2 of the same size, one being a solid chunk of nickel-iron and the other a loosely clumped collection of individual rocks(aka Dimorphos). The first would impact with more of its mass remaining while the second would break up with each individual piece having to survive entry. I doubt the sum of the second would equal the result of the first in impact damage. The second would have a much greater atmospheric heat bloom but both that and any impacts would be over a greater volume of atmosphere and land area. I’d bet there are still graduate students tackling the permutations of different classes of asteroids striking at different angles over land vs water and the variations in altitude and depth that could happen.

 

chatgpt is a glorified autocorrect.

Mass DOES have an effect based on mutual attraction, but not when we're talking about 10^15 differences in magnitude.

Ish... but ice vs metallic is, at most, 1 order of magnitude, and when we're talking gravitational influence, it's all about trajectory differences, not terminal characteristics.

 

You’re single order of magnitude only applies if the composition allows it to hang together but it’s the fact that different compositions won’t hold together the same way which will alter it from a single impact to many, each of which would be several orders of magnitude less. The total might be as great but the effect would be spread out with a greater portion occurring on the way in.

 

Like I said, negligible influence to to orbital trajectory, assuming no comet style outgassing. Plenty of difference in terminal characteristics.

Latest news from more observations have said it's most likely not hitting, anyway.

https://blogs.nasa.gov/planetarydef...gnificant-threat-to-earth-in-2032-and-beyond/

...

Starship Flight 7 recap video is up. Flight 8, NET Friday the 28th.

https://www.youtube.com/watch?v=Pn6e1O5bEyA

 

https://www.youtube.com/watch?v=Lx8qzcomV5A

IM-2 (moon) and 3 rideshares on this one. Deploys look fine, looks like they have signal, no word from Astroforge Odin (asteroid flyby), and the other two Chimera (GEO transfer vehicle) and Lunar Trailblazer (JPL lunar orbiter) haven't said anything.

 

From the latest Rocket Report - IFT-7 shook to death:
The verdict is in for Starship Flight 7. SpaceX believes the spectacular break-up of Starship's upper stage during its most recent test flight was caused by a harmonic response that stressed onboard hardware, leading to a fire and loss of the vehicle, Aviation Week reports. Higher-than-expected vibrations stressed hardware in the ship's propulsion system, triggering propellant leaks and sustained fires until the test flight ended prematurely. The rocket broke apart and deposited debris over the Turks and Caicos Islands and the Atlantic Ocean, and forced dozens of commercial and private aircraft to delay their flights or steer into safer airspace.

Whole lotta shaking … SpaceX's description of the problem as a harmonic response suggests vibrations during Starship's climb into space were in resonance with the vehicle's natural frequency. This would have intensified the vibrations beyond the levels engineers expected from ground testing. SpaceX completed an extended duration static fire of the next Starship upper stage to test hardware modifications at multiple engine thrust levels. According to SpaceX, findings from the static fire informed changes to the fuel feed lines to Starship's Raptor engines, adjustments to propellant temperatures, and a new operating thrust for the next test flight, which could launch from South Texas as soon as Monday.

 

Seeing this video makes me wonder if SpaceX has matured enough to survive the passing of Musk. Much like Apple had to plan for and survive Job’s death…

 

If you’re free on March 1st
https://fireflyspace.com/missions/blue-ghost-mission-1/


Also, High Def from the Moon..
https://youtu.be/yPy4lL0fFW0

 

Likely, though it'll likely make much more conservative decisions and take less technical risks (over time under new management). That said, the trajectory of reusable second stages has been set well enough that it's not going to alter much, I think. So a more conservative Starship would have spent longer on sunk cost of carbon fiber, likely landing legs, etc, much less focus on S2 reuse, etc. So New Glenn, basically.

...

Flight 8 is now NET Mar 3 (Monday) 1830 ET

 

Not starting over but still enough different from the previous iteration that it’s not just as simple as adding a few rings. I don’t expect IFT-9 to be a catch attempt since I doubt either the ship or Pad B to be ready for it in another 6-8 weeks. The pad could well be fully operational by IFT-10 but the ship still be in need of upgrades either for success reaching orbit, successful relight, successful deorbit burn, and successful reentry. So far it’s only been ballistic so I’d be a bit surprised if they skipped the combination of the last two(targeted deorbit burn and reentry) with this iteration before attempting a ship catch

 

While you are correct, Elon is in a hurry.

 

Elon in a hurry won’t make it work if it isn’t right, we’ll just get to see more BOOM and another launch until it is. They’ve been amazing at fixing issues as they arise but there’s still a lot to do.

 

Mars flyby by Europa Clipper today
https://www.space.com/the-universe/...ars-this-saturday-on-way-to-jupiters-icy-moon