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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
by tonmoy 5y ago
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?
- isoprophlex 5y agoIt'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...
- azernik 5y agoFor 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.)
- deleted 5y ago[deleted]
- eb0la 5y agoIMHO beign able to spot something with this size at this distance is really awesome.
- azernik 5y agoInterestingly, the images came from the Dark Energy Survey [1], which for entirely different different reasons is running a very sensitive and high-resolution scan of the sky in visible and near-infrared. This just happened to show up in a frame where they were looking for distant galaxies and events, and the Minor Planets Center noticed the thing. [1] https://en.wikipedia.org/wiki/Dark_Energy_Survey https://en.wikipedia.org/wiki/Dark_Energy_Survey
- jessriedel 5y agoYes, 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 around a planet and spontaneously be ejected. Now, something like this can work if you use an irreversible interaction like aerobreaking, but this dwarf planet has negligible atmosphere. You could also use the dwarf planet for a gravitational assist (basically bouncing off it like a billiard ball), but I think gravitational assists from the other planets are almost always more convenient and effective.
- tmhrtly 5y agoWhat if we crash landed into it? That would probably tick the irreversible box. Clearly engineering difficulties quite high though!
- Sharlin 5y agoThis is often jocularly called lithobraking and is typically not advisable.
- fouronnes3 5y ago> not advisable Unless you're NASA landing a probe on Mars in 1997.
- Sharlin 5y agoSeriously, the tandem failures of the Mars Polar Lander and Mars Climate Observer missions were probably something NASA as an organization needed at the time. A reminder that Space Is Hard, and you can only pick two of "faster", "better", and "cheaper". Since then, NASA's Mars program has grown in both scope and ambition, yet remarkably has had zero loss-of-mission failures during that whole time!
- cwkoss 5y agoCould a probe have a long tethered anchor, so as it does it's flyby the friction of the anchor dragging the surface would shed more delta-V than the weight of the system (in comparison to just loading up on more propellant)?