Apophis Rendezvous and Tagging (A.R.T.)

[mbartley]

In the SpaceX Falcon1 flight 4 thread, someone mentioned this add-on.

[ame="http://www.orbithangar.com/searchid.php?ID=3470"]A.R.T.[/ame]

It simulates a Falcon 1e with a spin-stabilized Star30 3rd stage and a small but capable little spacecraft, designed to intercept and land on the near-Earth asteroid Apophis. It also includes a nice detailed (AKA slow, on my computer at least!) Space-X Omelek island launch site as a base.

I just want to say how cool this add-on is. I managed to land on Apophis on my first try, with 15kg fuel remaining (17.2% - ship estimates 677 m/s remaining delta-V).

Next I want to try retasking this thing to land on Phobos or Deimos, or orbit the moon. The moon is definitely within performace capability, but since the upper stage is a solid rocket engine with fixed burn time, it may be tricky to plan. I'm not sure about Phobos or Deimos.

 

[BrianJ]

Hi,
glad you had some fun with ART and well done on making it to (and landing on!) Apophis. The original mission design by V.T.Thu was for a low orbit at Apophis, but I found that was not stable even in the medium term, so my thought was to go for "station keeping" nearby (like Hayabusa). I never thought about a NEAR/Eros style landing!

There should more than enough dV in the Falcon1e + Star30BP to go to the Moon. And given the hefty amount of dV on the spacecraft itself, I wonder if it wouldn't be possible to make a soft landing ?!

Going to Deimos/Phobos will be more challenging. I don't think there's enough dV to go there direct, so you could do an Earth flyby first, or maybe a Moon->Moon->Earth flyby sequence like Nozomi.
http://www.isas.ac.jp/e/enterp/missions/nozomi/index.shtml
http://www.stp.isas.jaxa.jp/nozomi/image/981231-s.GIF

You might even need to do a Mars flyby to get your insertion velocity down for the next pass.

regards,
Brian

Edit: Regarding the fixed burn-time 3rd stage - use the timing of your transfer orbit burn to adjust the required dV to match the 3rd stage dV - or off-load some propellant (edit the .scn file entry).

 

[mbartley]

There should more than enough dV in the Falcon1e + Star30BP to go to the Moon. And given the hefty amount of dV on the spacecraft itself, I wonder if it wouldn't be possible to make a soft landing ?! Regarding the fixed burn-time 3rd stage - use the timing of your transfer orbit burn to adjust the required dV to match the 3rd stage dV [...]

That's more or less what I've done with IMFD. Even so I ended up way off course to the moon after the Star30 burn, but with IMFD I was able to find one fairly big (400 m/s or so) mid-course correction burn that sent me towards a low inclination lunar orbit. There was plenty of fuel for orbit insertion.

I really wanted to launch straight from Earth orbit towards a polar lunar orbit, but I couldn't figure out how plan that, even after much screwing around with IMFD's target offset mode.

I didn't try landing. Maybe if I can get there without large course corrections I'll try it. Given it's fairly low accelleration I doubt there's much chance of landing at any particular place.

Going to Deimos/Phobos will be more challenging. I don't think there's enough dV to go there direct, so you could do an Earth flyby first, or maybe a Moon->Moon->Earth flyby sequence like Nozomi.

I've never had much luck planning flights like that. I guess A.R.T. could fly a normal direct flight into a highly eccentric Mars orbit at least. After that? Maybe after gradually aerobraking to lower that orbit's apoapsis a rendezvous might be possible. It would probably depend most on how much plane change is needed. Probably just a flyby is possible.

 

[astrosammy]

I've tried out getting to Mars, but even the Probe had not enough fuel left. But I'll try it again, my parking orbit was off-plane, so I needed more fuel.

Your addons are cool, Brian!

 

[BrianJ]

That's more or less what I've done with IMFD. Even so I ended up way off course to the moon after the Star30 burn, but with IMFD I was able to find one fairly big (400 m/s or so) mid-course correction burn that sent me towards a low inclination lunar orbit. There was plenty of fuel for orbit insertion.

I really wanted to launch straight from Earth orbit towards a polar lunar orbit, but I couldn't figure out how plan that, even after much screwing around with IMFD's target offset mode.

I've haven't had much luck with IMFD Target Intercept "Offset" mode either (trying to do the same thing with LRO). But just going for a normal intercept(no offset), you should be able to get into polar orbit using less than 100m/s dV for course corrections, I reckon. Getting the 3rd stage burn accurate is the trick - remember to start the burn exactly 30s before the IMFD Target Intercept nominal time.

I've never had much luck planning flights like that. I guess A.R.T. could fly a normal direct flight into a highly eccentric Mars orbit at least.

If I remember right, the 3rd stage can give ART about 3850m/s dV - what's the minimum dV from LEO to Mars? About ~4300m/s ? So that's not far off - does the Falcon1e 2nd stage have any fuel left after parking Orbit insertion? Maybe you could get to Mars direct!
What was MRO's orbit insertion dV at Mars? 2500m/s ?? Something like that I think, so maybe it could be done.

I quite like the idea of using an Earth flyby to get there though, think I'll give it a try

Cheers,
Brian


-----Posted Added-----

I've tried out getting to Mars, but even the Probe had not enough fuel left. But I'll try it again, my parking orbit was off-plane, so I needed more fuel.

Your addons are cool, Brian!

Well, thank you, astrosammy. Good luck with it


-----Posted Added-----

what's the minimum dV from LEO to Mars? About ~4300m/s ?

Bah! Talking rubbish again - more like 3700m/s, so no problems getting to Mars. Next launch window 13 Oct 2009.

 

[astrosammy]

I got into a 150x11000km Orbit now, after making aerobraking with a PeA of 50km. But the relative inclination to Phobos and Deimos is to high to get to them.

 

[n122vu]

In the SpaceX Falcon1 flight 4 thread, someone mentioned this add-on.

http://www.orbithangar.com/searchid.php?ID=3470

It simulates a Falcon 1e with a spin-stabilized Star30 3rd stage and a small but capable little spacecraft, designed to intercept and land on the near-Earth asteroid Apophis. It also includes a nice detailed (AKA slow, on my computer at least!) Space-X Omelek island launch site as a base.

I just want to say how cool this add-on is. I managed to land on Apophis on my first try, with 15kg fuel remaining (17.2% - ship estimates 677 m/s remaining delta-V).

Next I want to try retasking this thing to land on Phobos or Deimos, or orbit the moon. The moon is definitely within performace capability, but since the upper stage is a solid rocket engine with fixed burn time, it may be tricky to plan. I'm not sure about Phobos or Deimos.

I think that was one of my posts that mentioned it. BrianJ, thanks for this great add-on. Love using both the Falcon1e and also Omelek as a launch location. Awesome stuff. Keep up the good work!