# Solar triangles

Dustin Maki
TL;DR Summary
If a spacecraft could keep station at the 2nd focus of Earth's orbit, what useful observations could be made?
If a hypothetical spacecraft could keep station at the 2nd focus of Earth's orbit, what useful observations could be made?

Each minute sees a new solar triangle Earth Sun Craft (ESC). Swept area remains constant, as should length SC, and length CE + ES.
With the Sun as our point source, and instrumentation at Earth and Craft we should be able to precisely measure angles between each of our objects.

Might the sum of those angles exceed 180degrees?

Presumably the craft could be repositioned at the 2nd focus of other solar orbits. Could there be a better vantage point to observe orbital mechanics?

If you had access to a craft with this capability, what would you want to do with it?

What physics and engineering challenges are the highest barriers to making such a craft real?
For example; assuming Raptor Vacuum engines are used for station keeping, approximately how many kilograms of methane and LOX would would be consumed for that purpose in 1 Earth year.

What is the expected hull temperature facing the Sun at that point in space?

Sorry for all the questions and no answers. They just occurred to me and I thought others might like to know the answers as well.

Homework Helper
Gold Member
2021 Award
Summary:: If a spacecraft could keep station at the 2nd focus of Earth's orbit, what useful observations could be made?
The Earth's orbit is nearly circular. Set the controls for the heart of the Sun!

davenn
Dustin Maki
The Earth's orbit is nearly circular. Set the controls for the heart of the Sun!
Well that makes it rather simple then. That is the problem with lay physics, little appreciation for the scale of things.

PeroK
As PeroK says, the two foci of the Earth's elliptical orbit are not very far apart.

Lagrange points are more intetesting. We have at least one satellite, SOHO, at the L1 position. Satellites at L4 or L5 would give us a nice perspective on the Sun for day to day observation.

Klystron, davenn and russ_watters
Dustin Maki
@Ibix SOHO was at the back of my mind while thinking of this. So change the question such that Craft C is at L4.

Staff Emeritus
The soon to come James Webb Space Telescope will be located at the L2 Lagrange point.

Dustin Maki
@anorlunda those would be much more acute triangles than L4, but easier location to reach I suppose.

Gold Member
L points are ideal for lots of things. Unfortunately, maintenance and repair are difficult. Recent Space projects have demonstrated just how good our Engineering can be.

Hubble at L4 would still be as myopic as it started. But modern image processing software would probably have done a lot to improve the images.

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Staff Emeritus
L points are ideal for lots of things. Unfortunately, maintenance and repair are difficult. Recent Space projects have demonstrated just how good our Engineering can be.

Hubble at L4 would still be as myopic as it started. But modern image processing software would probably have done a lot to improve the images.
That is why I labelled the James Webb Space Telescope as really bold and daring. It can never be visited by repair missions.

Their major weapon would be the ability to upload revised software. Look at how well that worked for Voyager 1&2.

sophiecentaur