Kerbol probe + - Sun corona sample return mission

[Bill2462]

Just a quick mission to the Sun.

Goal : Collect a sample of stardust and bring it back to Kerbin.

How hard can it be ? (:

Kerbol probe +

Spacecraft :

Probe:

• Name : Kerbol probe +
• Mass : 6895 kg
• Propulsion : Ion engine
• Power supply: 4x RTG
• Dv : around 11 km/s
• Communication : 1x High gain antena
• Shielding : 1000kg sunscreen
• Recovery equipment : none

Sample return capsule :

• Mass : 700 kg
• Propulsion : none
• Power supply : 4x batteries
• Communication : 2x low gain ominidirectional antenas
• Shielding : Heatshield
• Recovery equipment : 1x main parachute.

 

Mission Log :

T - 0

Launch

T + 20 seconds :

Titan X rocket performs  pitch and roll manuver to maintain optimal ascent trajectory.

 

T + 1 minute and 30 seconds :

Solid rocket boosters burnout and seperation :

T + 2 minutes and 30 seconds :

Payload fairing separation :

T+ 4 minutes

Main engine cutoff and stage one separation.

 

T+ 5 minutes and 30 seconds :

Second stage engine fires for 5 minutes to put the probe in a solar orbit.

T+ 20 minutes

Kerbol probe + seperates from a second stage.

Spacecraft is now on a highly elliptic orbit around the sun with with AP far beyond Jool's orbit. 

T + 1 month

Spacecraft enters hibernation state for next 3 years.

 

T + 3 years and 256 days

Kerbol probe + fires it's Ion engine for 2 hours and 20 minutes. This maneuver drops Pe to around 500 000 km. 

(Unfortunately, the communication system was not sufficient enough so I had to waste some fuel and perform this  maneuver much earlier. )

T + 5 years and 120 days :

After 5 years of flight, Kerbol probe + finally reaches it's destination.

Due to the really high orbital speed, (>120 000 m/s), this part of the mission will last only for around 30 days.

 

T+ 5 years and 135 days:

The spacecraft pases it's peryapsis,  490 000 km above Sun surface.

 

T+ 5 years and 217 days

Spacecraft fires it's propulsion for 3 hours and 20 minutes in order to put spacecraft into return trajectory.

 

T+ 7 years and 90 days

Kerbin system entry. Probe performs slowdown burn to ensure that the return capsule will survive reentry.

 

T+ 7 years and 91 days :

Return capsule separates from the main probe.

T+ 7 years  91 days and 2 hours.

Return capsule reenters the atmosphere and lands in an ocean.

The end

[Geschosskopf]

Nice solar limbo   I imagine it took some fiddling to keep that asymmetrical thing from tumbling under thrust.

So why the high Ap to start with?  

[Bill2462]

Quote

I imagine it took some fiddling to keep that asymmetrical thing from tumbling under thrust.

No, The thrust was low (a few newtons ) so this wasn't a big problem.

 

Quote

So why the high Ap to start with?  

It saved a lot of fuel. At the altitude of kerbin's orbit I would have to burn >5km/s of Dv to get to the sun. Raising Ap beyond Jool's orbit dropped that value to around 2.5 km/s.

[Geschosskopf]

3 hours ago, Bill2462 said:

It saved a lot of fuel. At the altitude of kerbin's orbit I would have to burn >5km/s of Dv to get to the sun. Raising Ap beyond Jool's orbit dropped that value to around 2.5 km/s.

But how much did raising the Ap there cost to begin with?

[Zhetaan]

On ‎11‎/‎25‎/‎2017 at 4:33 PM, Geschosskopf said:

So why the high Ap to start with?  

That's called a bielliptic transfer.  When the higher orbit's SMA is greater than ... eleven times, I think ... that of the lower orbit, the bielliptic transfer is cheaper in delta-V than the Hohmann.  It requires three burns instead of two for the full transfer (or two instead of one for this sort of fly-by) but the relatively high cost of the initial burn to reach the high Ap is negated by the much cheaper cost to lower the Pe once there.  Given that Kerbin orbits at over thirteen Gm and the target Pe was half of a Gm, bielliptic was the way to go--the only real drawbacks to it are that has a minimum limit of effect and that it takes even more time than the Hohmann.

@Bill2462:

Nice mission!  What did you use for a core on the return probe?  I take it that you clipped it into the adapter?

Edited November 27, 2017 by Zhetaan

[Geschosskopf]

3 minutes ago, Zhetaan said:

That's called a bielliptic transfer...

I realize this, but was just wondering if the savings was all that much in this case.

I usually go to Moho bi-elliptically but always inwards, not outwards.  1st burn to put my solar Pe at Moho's AN or DN with Kerbin, 2nd burn to bring my solar Ap down between Eve and Moho.  Then wait to synch up with Moho.  Of course, my object is to minimize the capture burn at Moho, not do a fast solar flyby.

[Zhetaan]

3 hours ago, Geschosskopf said:

I realize this, but was just wondering if the savings was all that much in this case.

It depends on the choice of Ap, but my back-of-the envelope calculation (ignore Kerbin escape and the initial Oberth effect; just assume you're starting in space at Kerbin's altitude over the sun) gives about 6260 m/s for a Hohmann transfer and about 4310 m/s for a bielliptic for this mission.  The bielliptic is split between an initial burn of about 3090 m/s and a second burn of about 1220 m/s.  Of course, these numbers are off by a lot because of my initial assumptions, but the relationship between the Hohmann and bielliptic transfers should be apparent.

[DAL59]

On 11/25/2017 at 4:33 PM, Geschosskopf said:

Nice solar limbo   I imagine it took some fiddling to keep that asymmetrical thing from tumbling under thrust.

So why the high Ap to start with?  

Its a bielliptical transfer.  

[Bill2462]

On 27.11.2017 at 6:50 PM, Zhetaan said:

What did you use for a core on the return probe?  I take it that you clipped it into the adapter?

That is correct.

As a return capsule body, I used FL-A10 Adapter and yes there is a Probodobodyne OKTO2 command module and some batteries clipped inside.

I experimented with uncontrolled return capsule but the parachute was always destroyed during reentry so I had to use command module in order to deploy it manually.