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A dwarf planet coming within 11 AU of the sun over the next 10 years

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Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#71

Post by azernik »

ehsanu1 wrote: post #64
tmhrtly wrote: post #57

Earlier quoted context omitted.

What if we crash landed into it? That would probably tick the irreversible box. Clearly engineering difficulties quite high though!

It's a cool idea, but seems super sci-fi. Might need some wonder materials to make it feasible, even then that would be a really big crumple zone. Or flubber. Another crazy idea: latch on to the planet from the side, like a skateboarder hitching a ride by hanging on to a truck. Again, wonder materials required.

NASA and the Soviets didn't need any wonder materials, just airbags. (Though they did a lot of braking first - either with the atmosphere for NASA at Mars, or with thrusters for the Soviets at the Moon.)

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#73

Post by shkkmo »

jessriedel wrote: post #53
tonmoy wrote: post #38

Earlier quoted context omitted.

Is that really true? If we manage to get a spacecraft get captured by the dwarf planet's gravity and orbit it, would that not be a lot less delta-V compared to if we made the spacecraft achieve the dwarf planet's orbit around the sun just by itself?

Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it. You can't be captured by a planet's gravity alone. If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured). The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit aro…

> You can't be captured by a planet's gravity alone

Technically, this isn't completely true. There are gravity assist techniques that will allow you to dump speed by essentially adding your momentum to the object you are trying to orbit. The is basically an anti-slingshot manuever.

In practice, I believe the range of scenarios when this is possible with a dwarf planet is so small as to be practically useless.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#74

Post by azernik »

isoprophlex wrote: post #47
tonmoy wrote: post #38

Earlier quoted context omitted.

Is that really true? If we manage to get a spacecraft get captured by the dwarf planet's gravity and orbit it, would that not be a lot less delta-V compared to if we made the spacecraft achieve the dwarf planet's orbit around the sun just by itself?

It's a dwarf planet of ~ 200 km diameter. The thing has a miniscule gravity well, it won't matter much compared to launching from earth and matching orbits with it, i think...

For comparison, that's about 10% of the Moon's diameter, i.e. 0.1% of its volume. (The mass ratios are probably within that 0.1% ballpark, but can't tell for sure until we know more about its composition.)

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#76

Post by shkkmo »

CamperBob2 wrote: post #66
jessriedel wrote: post #53

Earlier quoted context omitted.

Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it. You can't be captured by a planet's gravity alone. If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured). The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit aro…

That's pretty cool. It's wildly counterintuitive, but if it weren't the case, the planets would be orbited by lots of captured asteroids and debris, instead of/in addition to being covered in craters. The only explanation for why that doesn't happen is that it can't happen.

The presence of natural satellites indicates this can indeed happen. It just requires a pretty unlikely orbital configuration.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#77

Post by EarthLaunch »

hownottowrite wrote: post #19
orliesaurus wrote: post #5

I wonder how/IF this will cause anything to spike solar flares? that's what's scary to me - all it takes is one big burst and bye bye to our tech....

It won’t do anything. Also, Carrington class events are very rare. You should worry more about space junk crashing into important things and even then it’s not much of a worry. https://warwick.ac.uk/newsandevents/pressreleases/likelihood...

> The analysis shows that ‘severe’ magnetic storms occurred in 42 out of the last 150 years, and ‘great’ super-storms occurred in 6 years out of 150

That seems extremely imminent, like in my lifetime. How many of these events would shut down tech for months or years? Are those odds worth risking civilization over?

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#78

Post by _Microft »

jbay808 wrote: post #36
bewaretheirs wrote: post #30

Earlier quoted context omitted.

Just launch a deep-space telescope; it would be easier. Soft-landing the telescope on an airless body would be harder (in delta-V terms) than just launching it into an equivalent solar orbit. And the body would block about half your view of the sky at any one time.

Could you get a nice gravity boost away from the sun by just following it for as long as possible?

The easiest way to think about this is as perfectly elastic collision between the spacecraft and the planet (mediated by gravity, but this is an unnecessary detail already).

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#79

Post by throwaway316943 »

messe wrote: post #14
jessriedel wrote: post #9

Earlier quoted context omitted.

New Horizons took a nearly straight shot to Pluto (just stopping by Jupiter on the way for a gravity assist). That trip took 9 years to travel 40 AU (not at constant speed, of courses, since it's constantly being drawn toward the Sun). This dwarf planet makes its closest approach at 10 AU, so you could do a fly by in less than 3 years if you wanted to pay for it. However, the science return from a flyby would be limi…

Getting into orbit would be rather difficult, as the probe would have have to match the planets velocity at perihelion. My instinct says it’s probably just on the edge of doable (although I’m not sure on which side), but I haven’t crunched the numbers. It would almost certainly need to be launched on a Delta-IV or Falcon Heavy class vehicle. EDIT: s/perigee/perihelion. I could say periapse and be neutral, but perihel…

Maybe starship will be ready with orbital refueling in time to make a faster trip. Imagine being able to do a sample return mission from such an object.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#80

Post by CamperBob2 »

shkkmo wrote: post #76
CamperBob2 wrote: post #66

Earlier quoted context omitted.

That's pretty cool. It's wildly counterintuitive, but if it weren't the case, the planets would be orbited by lots of captured asteroids and debris, instead of/in addition to being covered in craters. The only explanation for why that doesn't happen is that it can't happen.

The presence of natural satellites indicates this can indeed happen. It just requires a pretty unlikely orbital configuration.

No, it doesn't. No (rocky) planet has more satellites than craters, but every planet's gravitational field is larger than its surface.
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