[HN Gopher] NASA's Parker Solar Probe Reports Successful Closest...
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NASA's Parker Solar Probe Reports Successful Closest Approach to
Sun
Author : divbzero
Score : 77 points
Date : 2024-12-27 19:06 UTC (3 hours ago)
(HTM) web link (blogs.nasa.gov)
(TXT) w3m dump (blogs.nasa.gov)
| _joel wrote:
| The temperature and radiation it has to endure is impressive, but
| I'm more blown away by good old fashioned gravity assists to yeet
| the probe and not have it fall into a fiery well of gravity.
| ethbr1 wrote:
| 192 km/s is pretty insane.
|
| That's 0.06% of light speed?
|
| And a bit over 10x what the Voyagers are traveling at?
| holoduke wrote:
| Wonder what the time dilation would be. Must be in seconds
| with that soeed.
| belter wrote:
| By my rough calculations about 18 milliseconds of time
| dilation per day assuming 690,000 km/h - 430,000 mph.
| itishappy wrote:
| 1 / sqrt(1 - v^2 / c^2) 1 / sqrt(1 - v^2)
| (when v is in units of c) 1 / sqrt(1 -
| 0.0006^2) 100.000018% or about 5 seconds per
| year (I may have this reversed, but it doesn't
| really affect the numbers at this speed, just the sign.)
| bsder wrote:
| Is the dilation due to the Sun's gravity well larger than
| that?
| aeve890 wrote:
| Both from the sun gravity well and the high speed.
| Different kinds of time dilation.
| stouset wrote:
| Hitting the sun is actually surprisingly hard. It's harder than
| leaving the solar system. Earth orbits at around 30km/s and you
| need 42km/s (+12km/s) to escape orbit.
| Larrikin wrote:
| They plan to eventually destroy the sensors by giving them full
| exposure to the sun but sadly the probe won't actually crash into
| the sun
|
| https://en.wikipedia.org/wiki/Parker_Solar_Probe
| dtgriscom wrote:
| Any idea why? It's not like its orbit will ever near the Earth
| again, and even if it did trashing the sensors probably doesn't
| affect its orbit.
| wereHamster wrote:
| Getting to the sun is really hard. Any object flying at
| earth's orbit has so much energy that you need to reduce in
| order to get to the center. The probe simply doesn't have
| enough propellant to slow down that much. The only other way
| that I can think of is to perform a gravity assist that would
| send the probe straight into the sun. And if you miss, the
| probe becomes a molten blob of metal that will forever
| continue flying in a highly eccentric orbit around the sun.
| t1234s wrote:
| Does increasing the speed via repeated gravity assists improve
| the odds of the probe surviving during closer approaches to the
| sun?
| itishappy wrote:
| The opposite, actually. Increasing speed is the very thing that
| brings it closer to the Sun.
|
| To clarify a bit... The gravity assists from Venus actually
| decrease the probes instantaneous speed, which allows it to
| fall closer to the Sun. The act of falling towards the Sun is
| what generates speed, with more speed being generated during
| closer approaches.
| csunbird wrote:
| Most likely that they are usibg the gravity assists to decrease
| the orbit (e.g. slow down) not to increase the speed. As your
| orbit gets more and more elliptical, your closest point to the
| celestial body gets closer and your actual speed relative to
| the celestial body increases dramatically.
|
| It sounds contradictory, but think of that in this way: you
| have an incredible amount of energy stored in potential energy
| relative to sun and by decreasing your orbit you convert this
| to kinetic energy.
|
| Think about falling into the sun from several billion
| kilometers, but just missing it slightly because you still have
| a bit of horizontal momentum left.
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(page generated 2024-12-27 23:01 UTC)