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NASA DART mission: Spacecraft to be crashed head-on with an asteroid on September 26 to redirect it
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a425couple
Sep 21, 2022, 12:12:01 PM9/21/22
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https://www.cnbctv18.com/science/nasa-dart-mission-spacecraft-to-be-crashed-head-on-with-an-asteroid-dimorphos-didymos-on-september-26-14701801.htm
NASA DART mission: Spacecraft to be crashed head-on with an asteroid on
September 26 to redirect it
Read Time
5 Min(s) Read
By PTI
Sep 12, 2022, 11:04 AM IST (Published)
MINI
If the DART mission succeeds, humanity will have demonstrated a
destructive capability vastly exceeding that of nuclear weapons.
Allowing private corporations to map and alter asteroid orbits would
also be extremely dangerous.
The DART mission to redirect an asteroid is billed as potentially
planet-saving. But in the wrong hands it has seriously destructive
potential. In September 2022 an event of planetary importance will take
place. With the assistance of a privately funded rocket, NASA's DART
mission will test the feasibility of redirecting an asteroid.
The mission is, in NASA's words, to test and validate a method to
protect Earth in case of an asteroid impact threat. NASA's spacecraft
will crash head-on into a small asteroid called Dimorphos, with the aim
of altering its orbit around a larger asteroid, Didymos.
The excitement about such heroic possibilities is rooted in long-held
assumptions about expansion into space. Going higher must mean getting
better.
However, the consequences of the mission are much less positive than
space enthusiasts and many others believe. Given the immense violence
potential of fast-moving space objects, the question of whether asteroid
redirection is desirable roughly approximates to the question of whether
space activities increase or decrease the likelihood of war.
In their 1964 book Islands in Space: The Challenge of the Planetoids,
astronomers Dandridge Cole and Donald Cox envisioned manoeuvring
asteroids to serve as the ultimate deterrent, a planetoid bomb. At the
time, these plans were advanced as solutions to the threat of nuclear
war, specifically to the vulnerabilities of nuclear weapons based on Earth.
Never attempted, these schemes were shockingly extreme, even among the
apocalyptic military speculations of the 1950s and 1960s.
Cole and Cox wrote that a captured planetoid of between 2 kilometres and
8 kilometres in diameter would have the impact energy equivalent to
several million megatons, would create a crater 30 to 80 kilometres in
diameter, and would destroy whole countries through Earth shock effects.
They hastened to add that such devastation would not be anything near as
bad as a general nuclear war because there would be no nuclear fallout
carried by the winds to all parts of the Earth.
A captured planetoid would be the ideal deterrent system, they said,
because it could not be de-orbited in less than several hours and would
not be feared by a potential enemy as a surprise attack weapon.
Furthermore, an onrushing planetoid could not be intercepted or
deflected even if detected several days before impact.
Such an attack might even be carried out without much danger of
retaliation because it would be difficult to distinguish from a natural
catastrophe.
Although this scheme suggests criminal insanity, it fits comfortably
alongside other fortunately abortive and outlawed Cold War
investigations of geophysical weaponisation, such as harnessing
hurricanes, tornadoes, earthquakes, volcanoes and tsunamis for military
purposes.
Interstate military rivalry propelled much of human space activity. So
why do we believe conflicts will not be carried into space? People who
believe in the possibility of overcoming rivalries on the highly
interdependent Earth, where large-scale violence is effectively
suicidal, are deemed utopian.
But these same rival states exploring the manipulation of asteroids
equipped with titanic violence potential is, somehow, no problem. For
this reason, the alteration of the orbits of asteroids by any single
government or corporation should be explicitly outlawed.
However, while international organisations will travel to the asteroid
as observers, the DART mission is solely the preserve of US
organisations. How, when and by whom this technology is developed has
first-order implications for the human species and the fate of the Earth.
The technologies to divert an asteroid away from the Earth are
essentially identical to those needed to direct objects towards the Earth.
If the DART mission succeeds, humanity will have demonstrated a
destructive capability vastly exceeding that of nuclear weapons.
Allowing private corporations to map and alter asteroid orbits would
also be extremely dangerous.
Given asteroids' inherent mass-destructive potential, allowing private
companies answerable to only a handful of corporate owners to develop
this technology would be like allowing private firms to develop the
hydrogen bomb in the 1950s.
However, completely abandoning the mapping and alteration of asteroidal
orbits is unwise because the collision of such bodies with the Earth is
inevitable. This knowledge and technology are vital. Asteroid mapping
and diversion should therefore be undertaken only by a consortium of
leading states on Earth.
A deflection consortium could be assigned the task, given the sole legal
authority, and equipped with the resources to develop the capacity to
defend the planet from cosmic bombardment. Such an effort would fall far
short of bringing a world government into existence, reassuring those
who fear control by stealth.
The enduring mutual suspicion of states would impede the asteroid
consortium from becoming the seed of a world state. It could be staffed
and operated not by a distinct body of international civil servants but
rather by members of the militaries of the contributing states.
Like any human venture, a strategy of military cooperation for planetary
security would have its own risks and potential paths of breakdown. If
the planetary protection consortium were to disintegrate, the violence
capacity of asteroids would be possessed by several states.
But as long as this agency remained solely focused on its narrow
mission, and no private actors were permitted to engage in these
activities, states would have a strong incentive to sustain the
arrangement. Human beings have long dreamed of exploring the farthest
reaches of space.
Space is particularly prone to dreamy assumptions, beguiling illusions
and stark disorientations. But dream-walking into space is sleepwalking
into space. Space expansion should be recognised as having not only a
plethora of bad proposals but also a frightening potential for evil.
Also Read: NASA defers Artemis I launch to Sept 23-27 — why those dates
(Edited by : Sangam Singh)
Check out our in-depth Market Coverage, Business News & get real-time
Stock Market Updates on CNBC-TV18. Also, Watch our channels CNBC-TV18,
CNBC Awaaz and CNBC Bajar Live on-the-go!
Tags
asteroidNASA
PREVIOUS ARTICLE
New study finds evidence for many planets made of water, rock orbiting
small stars
https://www.cnbctv18.com/science/nasa-dart-mission-spacecraft-to-be-crashed-head-on-with-an-asteroid-dimorphos-didymos-on-september-26-14701801.htm
NASA DART mission: Spacecraft to be crashed head-on with an asteroid on
September 26 to redirect it
Read Time
5 Min(s) Read
By PTI
Sep 12, 2022, 11:04 AM IST (Published)
MINI
If the DART mission succeeds, humanity will have demonstrated a
destructive capability vastly exceeding that of nuclear weapons.
Allowing private corporations to map and alter asteroid orbits would
also be extremely dangerous.
The DART mission to redirect an asteroid is billed as potentially
planet-saving. But in the wrong hands it has seriously destructive
potential. In September 2022 an event of planetary importance will take
place. With the assistance of a privately funded rocket, NASA's DART
mission will test the feasibility of redirecting an asteroid.
The mission is, in NASA's words, to test and validate a method to
protect Earth in case of an asteroid impact threat. NASA's spacecraft
will crash head-on into a small asteroid called Dimorphos, with the aim
of altering its orbit around a larger asteroid, Didymos.
The excitement about such heroic possibilities is rooted in long-held
assumptions about expansion into space. Going higher must mean getting
better.
However, the consequences of the mission are much less positive than
space enthusiasts and many others believe. Given the immense violence
potential of fast-moving space objects, the question of whether asteroid
redirection is desirable roughly approximates to the question of whether
space activities increase or decrease the likelihood of war.
In their 1964 book Islands in Space: The Challenge of the Planetoids,
astronomers Dandridge Cole and Donald Cox envisioned manoeuvring
asteroids to serve as the ultimate deterrent, a planetoid bomb. At the
time, these plans were advanced as solutions to the threat of nuclear
war, specifically to the vulnerabilities of nuclear weapons based on Earth.
Never attempted, these schemes were shockingly extreme, even among the
apocalyptic military speculations of the 1950s and 1960s.
Cole and Cox wrote that a captured planetoid of between 2 kilometres and
8 kilometres in diameter would have the impact energy equivalent to
several million megatons, would create a crater 30 to 80 kilometres in
diameter, and would destroy whole countries through Earth shock effects.
They hastened to add that such devastation would not be anything near as
bad as a general nuclear war because there would be no nuclear fallout
carried by the winds to all parts of the Earth.
A captured planetoid would be the ideal deterrent system, they said,
because it could not be de-orbited in less than several hours and would
not be feared by a potential enemy as a surprise attack weapon.
Furthermore, an onrushing planetoid could not be intercepted or
deflected even if detected several days before impact.
Such an attack might even be carried out without much danger of
retaliation because it would be difficult to distinguish from a natural
catastrophe.
Although this scheme suggests criminal insanity, it fits comfortably
alongside other fortunately abortive and outlawed Cold War
investigations of geophysical weaponisation, such as harnessing
hurricanes, tornadoes, earthquakes, volcanoes and tsunamis for military
purposes.
Interstate military rivalry propelled much of human space activity. So
why do we believe conflicts will not be carried into space? People who
believe in the possibility of overcoming rivalries on the highly
interdependent Earth, where large-scale violence is effectively
suicidal, are deemed utopian.
But these same rival states exploring the manipulation of asteroids
equipped with titanic violence potential is, somehow, no problem. For
this reason, the alteration of the orbits of asteroids by any single
government or corporation should be explicitly outlawed.
However, while international organisations will travel to the asteroid
as observers, the DART mission is solely the preserve of US
organisations. How, when and by whom this technology is developed has
first-order implications for the human species and the fate of the Earth.
The technologies to divert an asteroid away from the Earth are
essentially identical to those needed to direct objects towards the Earth.
If the DART mission succeeds, humanity will have demonstrated a
destructive capability vastly exceeding that of nuclear weapons.
Allowing private corporations to map and alter asteroid orbits would
also be extremely dangerous.
Given asteroids' inherent mass-destructive potential, allowing private
companies answerable to only a handful of corporate owners to develop
this technology would be like allowing private firms to develop the
hydrogen bomb in the 1950s.
However, completely abandoning the mapping and alteration of asteroidal
orbits is unwise because the collision of such bodies with the Earth is
inevitable. This knowledge and technology are vital. Asteroid mapping
and diversion should therefore be undertaken only by a consortium of
leading states on Earth.
A deflection consortium could be assigned the task, given the sole legal
authority, and equipped with the resources to develop the capacity to
defend the planet from cosmic bombardment. Such an effort would fall far
short of bringing a world government into existence, reassuring those
who fear control by stealth.
The enduring mutual suspicion of states would impede the asteroid
consortium from becoming the seed of a world state. It could be staffed
and operated not by a distinct body of international civil servants but
rather by members of the militaries of the contributing states.
Like any human venture, a strategy of military cooperation for planetary
security would have its own risks and potential paths of breakdown. If
the planetary protection consortium were to disintegrate, the violence
capacity of asteroids would be possessed by several states.
But as long as this agency remained solely focused on its narrow
mission, and no private actors were permitted to engage in these
activities, states would have a strong incentive to sustain the
arrangement. Human beings have long dreamed of exploring the farthest
reaches of space.
Space is particularly prone to dreamy assumptions, beguiling illusions
and stark disorientations. But dream-walking into space is sleepwalking
into space. Space expansion should be recognised as having not only a
plethora of bad proposals but also a frightening potential for evil.
Also Read: NASA defers Artemis I launch to Sept 23-27 — why those dates
(Edited by : Sangam Singh)
Check out our in-depth Market Coverage, Business News & get real-time
Stock Market Updates on CNBC-TV18. Also, Watch our channels CNBC-TV18,
CNBC Awaaz and CNBC Bajar Live on-the-go!
Tags
asteroidNASA
PREVIOUS ARTICLE
New study finds evidence for many planets made of water, rock orbiting
small stars
Jim Wilkins
Sep 21, 2022, 7:52:45 PM9/21/22
to
"a425couple" wrote in message news:jJGWK.474995$iiS8....@fx17.iad...
If the DART mission succeeds, humanity will have demonstrated a
destructive capability vastly exceeding that of nuclear weapons.
Allowing private corporations to map and alter asteroid orbits would
also be extremely dangerous.
---------------------
The impact of DART will make at best a -very- small change, like a BB
against a battleship.
https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Test
"The impact of the 500 kg (1,100 lb)[26] DART at 6.6 km/s (4.1 mi/s) will
produce an estimated velocity change on the order of 0.4 mm/s, which leads
to a small change in trajectory of the asteroid system, but over time, it
leads to a large shift of path."
Striking the enemy where you expect them to be ten or twenty years from now
isn't a game changer. They'll have plenty of time to hit the asteroid
themselves, space Ping-Pong.
https://www.nasa.gov/feature/jpl/nasa-analysis-earth-is-safe-from-asteroid-apophis-for-100-plus-years
If the DART mission succeeds, humanity will have demonstrated a
destructive capability vastly exceeding that of nuclear weapons.
Allowing private corporations to map and alter asteroid orbits would
also be extremely dangerous.
The impact of DART will make at best a -very- small change, like a BB
against a battleship.
https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Test
"The impact of the 500 kg (1,100 lb)[26] DART at 6.6 km/s (4.1 mi/s) will
produce an estimated velocity change on the order of 0.4 mm/s, which leads
to a small change in trajectory of the asteroid system, but over time, it
leads to a large shift of path."
Striking the enemy where you expect them to be ten or twenty years from now
isn't a game changer. They'll have plenty of time to hit the asteroid
themselves, space Ping-Pong.
https://www.nasa.gov/feature/jpl/nasa-analysis-earth-is-safe-from-asteroid-apophis-for-100-plus-years
R Kym Horsell
Sep 21, 2022, 9:19:24 PM9/21/22
to
In alt.astronomy a425couple <a425c...@hotmail.com> wrote:
> from
> https://www.cnbctv18.com/science/nasa-dart-mission-spacecraft-to-be-crashed-head-on-with-an-asteroid-dimorphos-didymos-on-september-26-14701801.htm
>
> NASA DART mission: Spacecraft to be crashed head-on with an asteroid on
> September 26 to redirect it
>
> Read Time
> 5 Min(s) Read
> By PTI
> Sep 12, 2022, 11:04 AM IST (Published)
> MINI
>
> If the DART mission succeeds, humanity will have demonstrated a
> destructive capability vastly exceeding that of nuclear weapons.
> Allowing private corporations to map and alter asteroid orbits would
> also be extremely dangerous.
>
> The DART mission to redirect an asteroid is billed as potentially
> planet-saving. But in the wrong hands it has seriously destructive
> potential. In September 2022 an event of planetary importance will take
> place. With the assistance of a privately funded rocket, NASA's DART
> mission will test the feasibility of redirecting an asteroid.
>
> The mission is, in NASA's words, to test and validate a method to
> protect Earth in case of an asteroid impact threat. NASA's spacecraft
> will crash head-on into a small asteroid called Dimorphos, with the aim
> of altering its orbit around a larger asteroid, Didymos.
Just some numbers for the people at home:
> from
> https://www.cnbctv18.com/science/nasa-dart-mission-spacecraft-to-be-crashed-head-on-with-an-asteroid-dimorphos-didymos-on-september-26-14701801.htm
>
> NASA DART mission: Spacecraft to be crashed head-on with an asteroid on
> September 26 to redirect it
>
> Read Time
> 5 Min(s) Read
> By PTI
> Sep 12, 2022, 11:04 AM IST (Published)
> MINI
>
> If the DART mission succeeds, humanity will have demonstrated a
> destructive capability vastly exceeding that of nuclear weapons.
> Allowing private corporations to map and alter asteroid orbits would
> also be extremely dangerous.
>
> The DART mission to redirect an asteroid is billed as potentially
> planet-saving. But in the wrong hands it has seriously destructive
> potential. In September 2022 an event of planetary importance will take
> place. With the assistance of a privately funded rocket, NASA's DART
> mission will test the feasibility of redirecting an asteroid.
>
> The mission is, in NASA's words, to test and validate a method to
> protect Earth in case of an asteroid impact threat. NASA's spacecraft
> will crash head-on into a small asteroid called Dimorphos, with the aim
> of altering its orbit around a larger asteroid, Didymos.
dimorphos is around 1% of the mass of its "primary" didymos.
the object of the exercise is to change the mutual orbit
that is extremely low speed.
The period is 12 hrs with a semi-maj axis of only 2 km -- i.e. around
10% of walking speed.
The impact is expected to be a good fraction of the DART's orbital
speed of around 7 km/sec so the impulse will be around 1%
of the momentum of the relevant orbit.
You should see a significant change in the mutal orbit.
If they get the hit in real good. :)
R Kym Horsell
Sep 21, 2022, 11:36:17 PM9/21/22
to
In alt.astronomy R Kym Horsell <k...@kymhorsell.com> wrote:
> In alt.astronomy a425couple <a425c...@hotmail.com> wrote:
>> from
>> https://www.cnbctv18.com/science/nasa-dart-mission-spacecraft-to-be-crashed-head-on-with-an-asteroid-dimorphos-didymos-on-september-26-14701801.htm
>>
>> NASA DART mission: Spacecraft to be crashed head-on with an asteroid on
>> September 26 to redirect it
>>
>> Read Time
>> 5 Min(s) Read
>> By PTI
>> Sep 12, 2022, 11:04 AM IST (Published)
>> MINI
>>
>> If the DART mission succeeds, humanity will have demonstrated a
>> destructive capability vastly exceeding that of nuclear weapons.
>> Allowing private corporations to map and alter asteroid orbits would
>> also be extremely dangerous.
...
> In alt.astronomy a425couple <a425c...@hotmail.com> wrote:
>> from
>> https://www.cnbctv18.com/science/nasa-dart-mission-spacecraft-to-be-crashed-head-on-with-an-asteroid-dimorphos-didymos-on-september-26-14701801.htm
>>
>> NASA DART mission: Spacecraft to be crashed head-on with an asteroid on
>> September 26 to redirect it
>>
>> Read Time
>> 5 Min(s) Read
>> By PTI
>> Sep 12, 2022, 11:04 AM IST (Published)
>> MINI
>>
>> If the DART mission succeeds, humanity will have demonstrated a
>> destructive capability vastly exceeding that of nuclear weapons.
>> Allowing private corporations to map and alter asteroid orbits would
>> also be extremely dangerous.
More nummas.
By adjusting (e.g. "we hope") the orbital speed of the pair by around 1%,
adding in the non-linearities related to Kepler's laws, and remembering
that a small change integrated over time can get pretty large, we
see that the impact is liable to result in quite large discrepencies
between where the smaller asteroid will be even within 1/2 a day.
A side-on impact will adjust the orbital speed the most.
Just for fun I've run the 2 scenarios of speeding up and slowing down
the orbit by 1% of orbital speed.
Orbital speed +1%
Time Out of position
(h) (km)
1 1.02944
2 2.65322
3 5.13221
4 8.54131
5 12.902
6 18.2214
7 24.5016
8 31.7434
9 39.9465
10 49.1103
11 59.234
12 70.3161 <-- even after small number of hrs
smaller moon is out of position 70 km
Orbital speed -1%
1 1.00256
2 2.56019
3 4.92435
4 8.17017
5 12.3199
6 17.3809
7 23.3556
8 30.2449
9 38.0488
10 46.7664
11 56.3972
12 66.9403
So the moral is -- it small numbers are only small in context of
what an "average" number is.
Often on A.GW hillbillies talk about how small the annual change in
atmosphere is due to fossil burning. Or how small CO2 as a percent.
They forget the "small number" for CO2 is responsible for life on earth.
Doubling that over 150 years is likely a big deal.
Ditto for a small change in orbital speed. It adds up over time.
While the semi maj axis is not changed much the resulting change will
make e.g. an asteroid on the way to earth "fall short" or "overshoot"
the expected impact point by a big number of km.
Daniel65
Sep 22, 2022, 6:35:36 AM9/22/22
to
R Kym Horsell wrote on 22/9/22 11:19 am:
"semi-maj axis" ... the long "radius" (sort of) of the ellipse.
2km semi-maj axis ... so about 4km end-to-end
So that would make the 'orbit length' about 12km depending on semi-minor
axis!
12km in about 12 hrs, approx 1km/h
If 1km/h is approx 10% of your walking speed, you're cracking a pretty
decent walking pace (10km/h)!! ;-P
--
Daniel
2km semi-maj axis ... so about 4km end-to-end
So that would make the 'orbit length' about 12km depending on semi-minor
axis!
12km in about 12 hrs, approx 1km/h
If 1km/h is approx 10% of your walking speed, you're cracking a pretty
decent walking pace (10km/h)!! ;-P
--
Daniel
R Kym Horsell
Sep 22, 2022, 7:33:14 AM9/22/22
to
In alt.astronomy Daniel65 <dani...@nomail.afraid.org> wrote:
...
...
>> The period is 12 hrs with a semi-maj axis of only 2 km -- i.e. around
>> 10% of walking speed.
> "semi-maj axis" ... the long "radius" (sort of) of the ellipse.
> 2km semi-maj axis ... so about 4km end-to-end
> So that would make the 'orbit length' about 12km depending on semi-minor
> axis!
> 12km in about 12 hrs, approx 1km/h
> If 1km/h is approx 10% of your walking speed, you're cracking a pretty
> decent walking pace (10km/h)!! ;-P
Moral: errors add.
>> 10% of walking speed.
> "semi-maj axis" ... the long "radius" (sort of) of the ellipse.
> 2km semi-maj axis ... so about 4km end-to-end
> So that would make the 'orbit length' about 12km depending on semi-minor
> axis!
> 12km in about 12 hrs, approx 1km/h
> If 1km/h is approx 10% of your walking speed, you're cracking a pretty
> decent walking pace (10km/h)!! ;-P
Daniel65
Sep 23, 2022, 5:57:39 AM9/23/22
to
R Kym Horsell wrote on 22/9/22 9:32 pm:
Yeah!! That's why working in 'approx' is much better!! ;-P
--
Daniel
--
Daniel
R Kym Horsell
Sep 23, 2022, 6:05:52 AM9/23/22
to
What you need to reverse engineer what I posted is interval artithmetic.
Since all the numbers are whole or rounded it's kinda obvious you need
to decide whether the results make sense within the likely range of values.
E.g. 2/12 is not 1/6 but the interval allowing "2" to be any number between
1 and 3 and "12" to be any number between 11 and 13.
Using the normal value of 2pi then 7 km/hr lives inside the interval.
According to medical authorities you are suppoed to walk 7 km/hr for
1/2 an hour a day for good health.
--
How to weigh a pig:
1. Take a sturdy plank and carefully balance it on a sawhorse.
2. Tie the pig to one end of the plank.
3. Pile rocks of approximately the same size on the other end of the plank
until it is evenly balanced.
4. Guess the weight of the rocks.
Daniel65
Sep 24, 2022, 7:25:07 AM9/24/22
to
R Kym Horsell wrote on 23/9/22 8:05 pm:
> but the interval allowing "2" to be any number between 1 and 3 and
> "12" to be any number between 11 and 13.
the interval allowing "2" to be any number between 1.5 and 2.5 and "12"
to be any number between 11.5 and 12.5.
> Using the normal value of 2pi then 7 km/hr lives inside the
> interval.
2pi approximates 6.28, which I think means 7km/hr lives *outside* the
interval. (or, at least, outside my interval)
> According to medical authorities you are suppoed to walk 7 km/hr for
> 1/2 an hour a day for good health.
>
30 mins of exercise a day, sure, but I can't recall there ever being a
SPEED attached to it!!
--
Daniel
> In alt.astronomy Daniel65 <dani...@nomail.afraid.org> wrote:
>> R Kym Horsell wrote on 22/9/22 9:32 pm:
>>> In alt.astronomy Daniel65 <dani...@nomail.afraid.org> wrote:
>>> ...
>>>>> The period is 12 hrs with a semi-maj axis of only 2 km --
>>>>> i.e. around 10% of walking speed.
>>>> "semi-maj axis" ... the long "radius" (sort of) of the ellipse.
>>>> 2km semi-maj axis ... so about 4km end-to-end So that would
>>>> make the 'orbit length' about 12km depending on semi-minor
>>>> axis! 12km in about 12 hrs, approx 1km/h If 1km/h is approx 10%
>>>> of your walking speed, you're cracking a pretty decent walking
>>>> pace (10km/h)!! ;-P
>>> Moral: errors add.
>> Yeah!! That's why working in 'approx' is much better!! ;-P
>
> Pretty interesting for a guy that uses 6 for 2pi. :)
>
> What you need to reverse engineer what I posted is interval
> artithmetic. Since all the numbers are whole or rounded it's kinda
> obvious you need to decide whether the results make sense within the
> likely range of values. E.g. 2/12 is not 1/6
Umm! In the world in which I live, 2/12 *IS* 1/6.
>> R Kym Horsell wrote on 22/9/22 9:32 pm:
>>> In alt.astronomy Daniel65 <dani...@nomail.afraid.org> wrote:
>>> ...
>>>>> The period is 12 hrs with a semi-maj axis of only 2 km --
>>>>> i.e. around 10% of walking speed.
>>>> "semi-maj axis" ... the long "radius" (sort of) of the ellipse.
>>>> 2km semi-maj axis ... so about 4km end-to-end So that would
>>>> make the 'orbit length' about 12km depending on semi-minor
>>>> axis! 12km in about 12 hrs, approx 1km/h If 1km/h is approx 10%
>>>> of your walking speed, you're cracking a pretty decent walking
>>>> pace (10km/h)!! ;-P
>>> Moral: errors add.
>> Yeah!! That's why working in 'approx' is much better!! ;-P
>
> Pretty interesting for a guy that uses 6 for 2pi. :)
>
> What you need to reverse engineer what I posted is interval
> artithmetic. Since all the numbers are whole or rounded it's kinda
> obvious you need to decide whether the results make sense within the
> likely range of values. E.g. 2/12 is not 1/6
> but the interval allowing "2" to be any number between 1 and 3 and
> "12" to be any number between 11 and 13.
to be any number between 11.5 and 12.5.
> Using the normal value of 2pi then 7 km/hr lives inside the
> interval.
interval. (or, at least, outside my interval)
> According to medical authorities you are suppoed to walk 7 km/hr for
> 1/2 an hour a day for good health.
>
SPEED attached to it!!
--
Daniel
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