4 ms·

Does anyone know how much impact this has on weight at the highest vs lowest gravity point?

by crystaln 3y ago

jalk 3y ago
And would it make economical sense to build rocket launch pads at the lowest points?
- dredmorbius 3y ago
  Not appreciably (the delta is less than 1%, see my response to OP in this thread), but since lowest gravitational acceleration happen to coincide roughly with areas of maximal rotational tangential velocity, that is, of the Earth's rotation about its axis, of roughly 1,000 mph, the optimal siting of rocket launch facilities tends to be near the Earth's equator, where gravitational acceleration itself tends to be lower, and near where the lowest measured accelerations are found. Other factors would tend to dominate launch location choice, including particularly areas of open water east of the launch pad, useful both for deorbiting stages and in the event of any RUD[1] events in early-boost phase. ________________________________ Notes: 1. See <https://space.stackexchange.com/questions/10022/who-coined-the-phrase-rapid-unscheduled-disassembly https://space.stackexchange.com/questions/10022/who-coined-t...>
dredmorbius 3y ago
Interesting question. This article discusses identifying regions of gravitational variance, and the abstract discusses where gravitational pull at Earth's surface is highest (near the North Pole) and lowest ("at the top of the Huascaran mountain in the South American Andes"), but not by how much ... The project measures local gravitational acceleration across the surface of the Earth at 200m resolution. <https://www.sciencedaily.com/releases/2013/09/130904105345.htm https://www.sciencedaily.com/releases/2013/09/130904105345.h...> And the linked field map doesn't give specific measurements either. (Archive as original is 404): <https://web.archive.org/web/20160309210505/http://geodesy.curtin.edu.au/research/models/GGMplus/gallery.cfm https://web.archive.org/web/20160309210505/http://geodesy.cu...> The linked PDF article however does give values, on page 5: <https://web.archive.org/web/20160307144931/http://ddfe.curtin.edu.au/gravitymodels/GGMplus/hirt2013_ultrahighres_gravity.pdf https://web.archive.org/web/20160307144931/http://ddfe.curti...> Minimum: 9.76392 m * s^-2 Maximum: 9.83366 m * s^-2 Given a 100 kg human (somewhat heavier than typical, but simpler to compute), the difference would amount to a difference of 6.974 newton, or 1.567 pound-force. Or a delta of about 0.712%.
reaperman 3y ago
If you were on a boat at water level, there wouldn’t be any weight difference between the two points. The water level follows equipotential lines of gravity.

Does anyone know how much impact this has on weight at the highest vs lowest gravity point?

jalk 3y ago

And would it make economical sense to build rocket launch pads at the lowest points?

dredmorbius 3y ago
Not appreciably (the delta is less than 1%, see my response to OP in this thread), but since lowest gravitational acceleration happen to coincide roughly with areas of maximal rotational tangential velocity, that is, of the Earth's rotation about its axis, of roughly 1,000 mph, the optimal siting of rocket launch facilities tends to be near the Earth's equator, where gravitational acceleration itself tends to be lower, and near where the lowest measured accelerations are found. Other factors would tend to dominate launch location choice, including particularly areas of open water east of the launch pad, useful both for deorbiting stages and in the event of any RUD[1] events in early-boost phase. ________________________________ Notes: 1. See <https://space.stackexchange.com/questions/10022/who-coined-the-phrase-rapid-unscheduled-disassembly https://space.stackexchange.com/questions/10022/who-coined-t...>

dredmorbius 3y ago

Interesting question. This article discusses identifying regions of gravitational variance, and the abstract discusses where gravitational pull at Earth's surface is highest (near the North Pole) and lowest ("at the top of the Huascaran mountain in the South American Andes"), but not by how much ... The project measures local gravitational acceleration across the surface of the Earth at 200m resolution. <https://www.sciencedaily.com/releases/2013/09/130904105345.htm https://www.sciencedaily.com/releases/2013/09/130904105345.h...> And the linked field map doesn't give specific measurements either. (Archive as original is 404): <https://web.archive.org/web/20160309210505/http://geodesy.curtin.edu.au/research/models/GGMplus/gallery.cfm https://web.archive.org/web/20160309210505/http://geodesy.cu...> The linked PDF article however does give values, on page 5: <https://web.archive.org/web/20160307144931/http://ddfe.curtin.edu.au/gravitymodels/GGMplus/hirt2013_ultrahighres_gravity.pdf https://web.archive.org/web/20160307144931/http://ddfe.curti...> Minimum: 9.76392 m * s^-2 Maximum: 9.83366 m * s^-2 Given a 100 kg human (somewhat heavier than typical, but simpler to compute), the difference would amount to a difference of 6.974 newton, or 1.567 pound-force. Or a delta of about 0.712%.

reaperman 3y ago

If you were on a boat at water level, there wouldn’t be any weight difference between the two points. The water level follows equipotential lines of gravity.