Mercury rocket at the mercy of solar gravity well

https://www.bbc.com/news/science-environment-45838991

On Friday, October 19, 2018 at 8:25:38 PM UTC+1, RichA wrote:
https://www.bbc.com/news/science-environment-45838991

Gravity well indeed !, another nuisance lost in 'warped space' with little understanding of the back and forth motion of Mercury around the Sun.

https://spacefan.org/wp-content/uplo.../11/01/222.jpg


The variable speeds of planets may be a top-down approach where the Sun also travels through spacein the journey of the solar system around the galactic carousel so the planets spend half their orbital traveling in the direction with the Sun and the other half going in the opposite direction. The closer to the Sun the faster planets move, not just each individual planet (Venus moves faster than the Earth) but each planet itself left a magnetic deflection.

https://spacefan.org/wp-content/uplo.../fomalhaut.jpg

These dopes following theorists from 100 years ago and their effin 'gravity wells' - no need to say grow up as I already know you are lost in the past..

On Friday, October 19, 2018 at 8:25:38 PM UTC+1, RichA wrote:
https://www.bbc.com/news/science-environment-45838991

Gravity well indeed !, another nuisance lost in 'warped space' with little understanding of the back and forth motion (direct /retrograde motion) of the faster moving Mercury around the Sun in a smaller circumference.

https://spacefan.org/wp-content/uplo.../11/01/222.jpg


The variable speeds of planets may be a top-down approach where the Sun also travels through space in the journey of the solar system around the galactic carousel so the planets spend half their orbital traveling in the direction with the Sun in a galactic orbital direction and the other half going in the opposite direction. The closer to the Sun the faster planets move, not just each individual planet (Venus moves faster than the Earth) but each planet itself seems to experience this electromagnetic deflection.

https://spacefan.org/wp-content/uplo.../fomalhaut.jpg

These unfortunates following theorists from 100 years ago and their effin 'gravity wells' - no need to say 'grow up ! 'as I already know you are lost in the past and can't look in at the structure of the inner solar system like men -

https://www.universetoday.com/wp-con...Dec27-2013.jpg

On Friday, October 19, 2018 at 1:25:38 PM UTC-6, RichA wrote:
https://www.bbc.com/news/science-environment-45838991

It is certainly a complicated mission.

Naturally, just launching a spaceship directly to Mercury on a Hohmann orbit is
impractical, requiring too much fuel.

Mariner 10, therefore, was launched on an orbit around the Sun that took it to
Venus, and Venus' gravity then changed its course so that it would fly past
Mercury. The orbit was chosen so that it would pass by Mercury again on
subsequent orbits, and so it had three chances to take pictures and make
measurements.

Today, we have more computer power - and the BepiColumbo mission is more
ambitious, as it is intended to place the vehicle in orbit around Mercury.

And so, to save fuel...

First, the spaceship will encounter the Earth again, to give it a gravity assist
so that it can get to Venus.

Then it will pass by Venus twice, for two gravity assists, so that it can get to
Mercury.

And when it can reach Mercury, it will pass by Mercury *six* times, losing
velocity relative to Mercury each time, until it can finally orbit Mercury with
just a small amount of thrust for the course correction.

I think there have been other recent space missions which have used similar
methods to reach their goals - particularly when they are directed at Mercury.

John Savard

On Wednesday, October 24, 2018 at 12:38:56 AM UTC-6, Quadibloc wrote:

I think there have been other recent space missions which have used similar
methods to reach their goals - particularly when they are directed at Mercury.

My memory was not playing tricks on me. MESSENGER also encountered the Earth once,
and then Venus twice, to get to Mercury. But then it limited itself to only
*three* encounters with Mercury before having a low enough relative velocity for
its purposes.

John Savard

On Wednesday, October 24, 2018 at 12:41:50 AM UTC-6, Quadibloc wrote:

My memory was not playing tricks on me. MESSENGER also encountered the Earth once,
and then Venus twice, to get to Mercury. But then it limited itself to only
*three* encounters with Mercury before having a low enough relative velocity for
its purposes.

Given that Jupiter takes 12 years to orbit the Sun, and Saturn takes 30 years to
do so, it's not surprising that such complicated methods aren't used for
missions to the outer planets, and instead only relatively simple and
straightforward gravity assists are used.

While the New Horizons mission was able to do a flyby of Pluto, putting a probe
in orbit around Pluto would be difficult.

And putting a probe in orbit around a closer, but still distant, body would seem
to be out of the question. Jupiter has intense radiation belts, and presumably a
similar problem would exist for the other gas giants.

Placing a space probe at Jupiter's Trojan points might seem hazardous - there
are asteroids there - but such hazards are overstated.

But it would be easy enough to send a probe to do a Jupiter flyby, and have the
flyby provide a gravity assist that leads to the probe orbiting between Jupiter
and Saturn, and the period of the orbit could be chosen so that the probe won't
encounter Jupiter again for a long time.

However, a probe independently orbiting the Sun would seem to have the problem
for my purpose that its position could not be determined with high accuracy.

While Hipparcos has done great work in deterimining the distances to many stars,
ideally to be sure of the accuracy of a distance, one would like photographs of
the star's position against a background of more distant stars. That's the
conventional way that stellar parallaxes were obtained.

The Earth's orbit around the Sun provides a 2 AU baseline for such observations.
A probe orbiting a planet more distant from the Sun than the Earth could provide
a longer baseline. Observations with a baseline from the site of the probe to
the Earth could be made simultaneously, avoiding the need to account for the
Sun's own proper motion.

Of course, this is an expensive way to obtain a small improvement in accuracy,
which is likely why it isn't being considered. But given the uncertainty in the
cosmic distance scale, it would be nice to do something...

John Savard

On Thu, 25 Oct 2018 00:43:32 -0700 (PDT), Quadibloc
wrote:
While Hipparcos has done great work in deterimining the distances
to many stars,
ideally to be sure of the accuracy of a distance, one would like
photographs of
the star's position against a background of more distant stars.
That's the
conventional way that stellar parallaxes were obtained.

Many traditional observing methods in astronomy have been abandoned.
For instance, transit circle measurements are no longer used to
determine the Earth's rotation, instead GPS satellites are used for
that.



The Earth's orbit around the Sun provides a 2 AU baseline for such
observations.
A probe orbiting a planet more distant from the Sun than the Earth
could provide
a longer baseline. Observations with a baseline from the site of
the probe to
the Earth could be made simultaneously, avoiding the need to
account for the
Sun's own proper motion.


Of course, this is an expensive way to obtain a small improvement
in accuracy,
which is likely why it isn't being considered. But given the
uncertainty in the
cosmic distance scale, it would be nice to do something...

Gaia, the successor to Hipparcos, is in operation since a few years
back. While Hipparcos was situated in LEO, Gaia is situated near the
L2 Sun-Earth Lagrangian point, therefore Gais baseline isn't much
larger than Hipparcos' baseline. Despite this, Gaia obtains much
higher precision, through a larger mirror and improved measurement
techniques.

So something is done.

What makes theorists dull and boring is their inability to appreciate how the terms 'average' and 'constant' became interchangeable when applied to the planet's rotation and the attendant Lat/Long system. Even demonstrating that the Lat/Long system is an outrigger of the calendar framework like the more recent RA/Dec reckoning doesn't register with these people.

The rotation of the Earth is anchored to noon (there is nothing comparable between sunset to sunrise) so in dynamical terms a location and their meridian is exactly half way between the circle of illumination at natural noon regardless of latitudinal speed of hemispherical season.

The neat trick of substituting the average 24 hour day for constant rotation over 360 degrees is such an exquisite experience for those who can rise to the emergence of timekeeping via the first annual appearance of a star as an orbital marker for the position and orbital motion of the Earth.

The people who bypassed the Sun as an anchor for rotation made a mistake. All generations of people find it impossible to believe they are inferior to previous generations but in this case those who can bypass the error and return to a stable foundation for both timekeeping and the astronomy of cause and effect will be doing themselves and the wider world a favour.