Solar Escape

August 22nd, 2012 | Posted in Orbiter Simulation | Comments Off on Solar Escape

I was in one of *those* moods this morning so just for the heck of it I tried something in orbiter that I’d never heard of anyone doing before.  (I’m sure it’s been done, I’ve just never seen anything about such events.)

I decided to try a gravity assist slingshot maneuver.  The object I chose to slingshot around was the sun.

I set this up in Orbiter 2006p1 because that version actually runs on my laptop and that’s where I was when I thought of this craziness.

date of mission start

I used the scenario that starts with the default DeltaGlider docked at the International Space Station with a full load of fuel.  I decided that for this mission, the ship would have twice it’s normal fuel capacity.  Not knowing any quick way to achieve this I used the scenario editor to refuel my ship one time when it’s initial supply ran out.

orbit at mission start

The first screenshot above, taken about a minute after undocking from the ISS, shows the date that this mission started.  The second screenshot shows my orbital parameters as of mission start.  Note that “Vel” on Orbit MFD is the ship’s orbital velocity expressed in meters per second.  This will be important to know later.

After doing a bit of navigation planning that I am sure none of the navigation tools were intended to do, I turned the ship prograde and began a main engine burn to escape Earth orbit.  Once I had achieved something over escape velocity I shut down the engines and coasted for a few days (using 100,000x time acceleration to speed things up a tad.)

Once I was far enough out from Earth for it to no longer be the primary gravitational influence I switched Orbit MFD to reference the sun instead of Earth and copied that information to the HUD so that I could turn the ship retrograde in reference to the sun.

Once in position I began another main engine burn.  The object of this one was to lower the periapsis (lowest point) of my orbit around the sun.  I burned through all of my remaining fuel and then used the scenario editor to refill my tanks and continue the burn.  (Note, I only allowed myself to do this once and then only because I wanted this trip to have twice the normal fuel supply and this was the quickest way to do that.)

I shut down the engines with about 17 kilograms of fuel remaining.  My periapsis was right where I wanted it, 600 kilometers above the surface of the sun.

At this point I went into cruise mode.  I used time acceleration to speed things along as I closed in on the sun on the craziest orbit I’ve ever heard of.  Along the way I used the remaining fuel to make more and more frequent course corrections to keep my periapsis as close to 600 kilometers as I could.

As I approached periapsis, my orbital velocity climbed.  This is to be expected.  As your ship approaches periapsis around any object is the time when it’s going to have the highest velocity.

At one point, I think it was roughly a week before periapsis, my velocity was well over 170 kilometers per second and climbing fast.

As you can imagine, when I reached periapsis things were happening really fast even without time acceleration.  Almost before I knew it I had reached periapsis and was flung outward, having gained an insane amount of momentum from the sun.  I have to admit that I sat there for a few minutes watching the “Alt” (altitude) readout on Orbit MFD climb.

It only took a few seconds for it to be high enough to be expressed in Astronomical Units (an A.U. is the mean radius of the Earth’s orbit around the sun.  approximately 93 million miles.). 

At that point I thought to set time acceleration to 0.1x and take another screenshot.  This one shows the date, Saturday May 29th, 2001 08:30:38 GMT

Below is the Orbit MFD display at that time.  My distance from the sun at that time was so far that the altitude was displayed as 0.392 parsecs!  To say the very least, I wasn’t in Kansas anymore.

final orbit data

Remember I said that this MFD shows velocity in meters per second?  Take a look at that picture again.  I’m going so fast that it’s shown as 0.168 AU per second.

How’s that for breaking speed records?

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