Challenge Martian moons tour

[dgatsoulis]

This is a challenge for the stock Deltaglider, based on the "Mars - Retrieve Payload from Phobos and Deimos" scenario that comes with the XR2 Ravenstar.

Description:
"Launch from Olympus base, land on both Martian moons and then return and land within 50 km of the base. You have 24 hours from the moment you ignite your engines. Δv budget: 7300 m/s"

Unzip the attached file in your Orbiter directory and run the Challenges Anthology\Deltaglider\2.Martian moons tour scenario.

The scenario comes with a lua script that checks if you have completed the goals of the mission and gives you a score in terms of how much Δv you used once the mission is complete.

You get a "mission failure" message if:
-You land back at Olympus without having landed on both moons.
-You land at a distance greater than 50 km of Olympus base.
-You land with a high vertical speed. (vs < -10 m/s).
-You fail to complete the challenge within 24 hours from engine ignition.

This scenario is a test for an addon that I'm making called Orbiter Challenges Anthology. I have gathered 9 of my favourite challenges and made scripts for all of them, similar to the one you see in this challenge. So please send me feedback of what you think of the script. (Intro, notes and messages placement, etc).


Have fun, happy orbiting.


------------------EDIT-----------------------

A few screenshots of a successful mission.

I wasn't very careful with my burns, ended up using ~7250 m/s of the available 7300.

-----------------------------------EDIT-----------------------------------

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dgatsoulis​

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Max Pain​

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flytandem​

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6691.00​

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blixel​

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6757.18​

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XR2 Ravenstar​

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--edit: DGIV and XR2 attachments moved to this post.

 

[flytandem]

That was fun Dgat. Thanks.

 

[dgatsoulis]

DGIV and XR2 update

An update that now includes the DGIV and the XR2.

Try to complete the challenge in your favourite spacecraft!

-The XR2 comes with it's own xrcfg file that overrides the XR2RavenstarPrefs.cfg, so every challenger uses the same configuration.

-For the DGIV you have to use the DEFAULT SETTINGS.

--edit the attachment has been moved to post #1. If you will use the Ravenstar, you only need to download the XR2 patch file.
Unzip the attached file in your Orbiter directory and run the Challenges Anthology\DeltagliderIV\2.Martian moons tour or the Challenges Anthology\XR2 Ravenstar\2.Martian moons tour scenarios for the DGIV or XR2 challenge respectively.

Use this thread to post your scores.
A top 5 scoreboard for each spacecraft will be kept and updated regularly on post #1 of this thread.

A snapshot with the "challenge completed successfully..." message is required and also the type of ship you completed the challenge with.

Have fun, happy orbiting
and see you on the scoreboards!

 

[asbjos]

I did the challenge, and got as far as to Deimos (I had successfully landed on Phobos), but when I should land, I forgot that Pe-time is time to lowest altitude from center, not time to surface impact, so I fired the engines too late and made a new crater on Deimos at a speed of 300 m/s. Luckily, StateSaver saved the scenario some minutes before, so I could try again, but it doesn't save progress in scripts, so the counter started all over again...

But by screenshots with time indicators and time of landing on Olympus, I can calculate that I landed 15.9 km from Olympus (I have little experience at precise Mars landings) with 251.14 of Delta V left (65.93 kg in main tank and 3.35 in RCS tank) after a 29 hour, 8 minute and 21 second long journey.

That means that I used 5 hours too much. Well, well... Back to the screen.

 

[palebluevoice]

Gotta try this sometime...thanks!

 

[dgatsoulis]

I did the challenge, and got as far as to Deimos (I had successfully landed on Phobos), but when I should land, I forgot that Pe-time is time to lowest altitude from center, not time to surface impact, so I fired the engines too late and made a new crater on Deimos at a speed of 300 m/s.

I know the feeling. :facepalm:
Has happened to me alot while looking at the distance, in the velocity match program of IMFD and not looking at the altitude in the surface HUD.

Luckily, StateSaver saved the scenario some minutes before, so I could try again, but it doesn't save progress in scripts, so the counter started all over again...

When you hit Deimos at that speed didn't you get a "mission failure: Hard surface impact..." message?
I had thought that someone might want to save the scenario and pick it up later. Unfortunately this cannot happen because the timer starts counting when you ignite your main/hover engines, so this is a mission that has to be completed in a single session.
It wouldn't be a problem if the timer began at scenario start, but that wouldn't give you enough time to find which launch window is more efficient and which moon to visit first.

But by screenshots with time indicators and time of landing on Olympus, I can calculate that I landed 15.9 km from Olympus (I have little experience at precise Mars landings) with 251.14 of Delta V left (65.93 kg in main tank and 3.35 in RCS tank) after a 29 hour, 8 minute and 21 second long journey.

That means that I used 5 hours too much. Well, well... Back to the screen.

Not a bad first try asbjos.:thumbup: The mission is all about timing your arrivals and departures correctly. There is plenty of dV to complete it in time.

Gotta try this sometime...thanks!

:thumbup:Looking forward to reading how your first try goes.

 

[asbjos]

Yes, I got the "hard impact" message.
Thanks for the challenge, it was fun and challenging!
I used TransX for the transfers, but it doesn't seem to either give the opportunity or even show launch azimuth and best launch time when you are traveling from a planet's surface to an object orbiting the same planet. Also, I can't plan transfers to moons when landed. Is this right? I have searched for off-plane Earth to Moon tutorials where I start landed on Earth, which would give me the answer, but I can't find anyone. Could you point me somewhere?

 

[dgatsoulis]

Yes in TransX you cannot create a plan for a moon while landed, you have to already be in orbit. My tool of choice for this challenge was IMFD.
But you can always "get back to basics". Have you tried the Tutorials\DG to the Moon scenario?

Or you can try to use surrogate ships already in Mars orbit and on the moons and make test runs. (The challenge will be a failure, because of the added vessels). But that's ok you can use them to find the launch windows and then try the dates on the actual challenge.

Also a great tutorial for a direct Earth-Moon transfer is in Mark&tommy's first playback from the [ame="http://orbithangar.com/searchid.php?ID=4142"]IMFD Full Manual/Playbacks[/ame]

Hope this helps.

 

[blixel]

...

 

[dgatsoulis]

It's not that hard to make a script like that. What would be needed is a cost for the fuel per kg and for time per second.
Then you could tie a money_fuel value to the fuel you have used and a money_time value for the time that has passed.

pseudo-script:

cost_fuel = (x)
fuel = getfuelmass
money_fuel = fuel*cost_fuel

cost_time = (y)
time = getsimtime
money_time = time*cost_time

total_money = money_fuel+money_time
total_money_left = (z) - total_money

--(z) can be an artitrary value of the cost of full fuel tanks + the cost of a (t) amount of time.

But I dont see it having much use. I mean if you want to make a transfer that would cost you 1000 m/s in dV and you saw that you have 200,000$ left, how would you know if it's enough to make the burn and wait untill you reach your target?

 

[asbjos]

I tried a second time with a new method, but the time went up half an orbit before my intercept with Deimos. If it wasn't for that you have done the scenario, I would believe that it was impossible...

While I write this, I think that I've found another method! I'll try it, but not tonight.

 

[dgatsoulis]

The maths suggest that the "lower limit" for this challenge is:

Δv: ~6500 m/s
Time: ~17.5 hours

That's just taking into consideration the transfers and the time it takes to make them. The "reallity" will be a bit different of course, but it is definitely doable with lots of Δv and time to spare.

 

[Veterok]

I get the mission failed due to fuel added in scenario editor message as soon as I touch the throttle.

 

[asbjos]

Sounds that you don't have unchecked "Auto-refuel on pad". Try to turn that off.

 

[dgatsoulis]

I took another shot at it using the same strategy as the first time, but I paid a lot more attention on the burns. The result was pretty good (saved about 325 m/s).

Flytandem send me a PM with his score (6691 m/s). He used a completely different strategy which obviously has the potential for the most significant savings.

There is still lots of room to reach the theoretical "perfect" flight: (6500 m/s).

Scoreboard on post #1 updated.

 

[blixel]

Nice challenge. I think I vaguely remember when this was posted last August. At the time, I don't think I was confident enough in my abilities to even attempt it. And it wasn't long before I totally forgot this challenge existed.

Your recent Lunar Landing challenge brought my attention back to this forum and I noticed this Martian moons tour challenge again.

I gave it a shot and recorded the whole thing. The video isn't interesting enough to post, so I'll just post some screenshots from the video.

Unfortunately I failed to complete the mission on time. I was over the time limit by several hours. I also experienced a CTD for no apparent reason during the flight, and that caused the script to reset itself when I resumed from my saved state.

Phobos:

CTD at Deimos ruined my joy

Deimos take two:

My Olympus landing wasn't very good. I was quite annoyed by the CTD so I rushed through the landing with a lot of 10x, and that caused me to run out of energy really early. So I came up short of the target by about 150km, and I was over the time limit.

If I hadn't rushed the landing, I know I would have made it within 50km of Olymps. I'm certain I wouldn't have made it to the landing pad, and I wouldn't even attempt the runway. But even if I had made it, I was too late getting there.

Will try again soon. After this experience, my main concern is beating the clock. Edit: I realize what I have to do though. It's a timing challenge mostly. If you're going from Olympus to Phobos to Deimos, then Deimos needs to be at just the right place in its orbit around Mars so that when you arrive at Phobos and get ground contact, you can then immediately leave Phobos, raise your Apoapsis up to Deimos, and then catch Deimos on the other side before finally lowering your periapsis back down to Mars and landing at Olympus.

 

[dgatsoulis]

Not far from success. :thumbup:

I think a challenge-busting series would make a nice addition to your YouTube Channel.

 

[blixel]

Not far from success. :thumbup:

It still feels like I've got a ways to go before I'll crack this one. I understand the timing component, but I'm having a bit of trouble figuring out an appropriate time to launch. If Phobos is in a good position for a quick rendezvous, then Deimos never seems to be where it needs to be.

And if Deimos is in a good position for a good Phobos to Deimos rendezvous, then Phobos isn't in the right place for launch. I can't afford to take off and sit on Phobos for an extended period. There just isn't enough time for that.

Once I solve that puzzle, I'm pretty confident I'll get it in short order. Though, I do have concerns about landing within 50km of Olympus at < 10 m/s. That isn't something I have any experience with. All my Olympus landings have relied on having sufficient fuel to do a retro engine braking burn + hover. It's an expensive way to land, but that darn Martian atmosphere is just thick enough to be a big pain in the neck, but way too thin for Earth-like landings.

That brings me to a question about the script in this challenge. Would it be possible to have it write the MJD out to a "dat" file at the time of launch, and have the goals saved in that file as well?

That way if you have a CTD like I did, or if you just want to save your progress and resume later you can pick back up and still have correct data.

The data could just be like: 56425.602454 1 1 0

The first piece is the MJD at the moment of ignition, the second bit is a true/false value for Phobos ground contact, the 3rd piece is a true/false value for Deimos ground contact, and the last bit is a true/false value for having landed back at Olympus successfully.

So in the above example, we have established ground contact at Phobos and Deimos (those bits are 1), but we have yet to land back at Mars (that bit is still 0.)

I'm not sure if that's a simple thing to add to the script, or if it's really complicated?

I think a challenge-busting series would make a nice addition to your YouTube Channel.

I have on my "to-do" list that I want to do a Challenge Accepted series.

---------- Post added at 05:06 PM ---------- Previous post was at 02:37 PM ----------

So disappointing.

At least I have the timing worked out. I know I can make the whole trip in the allotted time. Now I just have to make sure I conserve enough energy to get to the base on the way back.

 

[Max Pain]

Tried the challenge today. I think it's a though one.

First I tried without thinking about the timing, which doesn't work of course. Then I did some calculations and worked out the timing.
The next time I tried the timing was OK but when I was at Deimos I didn't even have enough fuel to get back to Mars :facepalm:.

Have to try again.

 

[blixel]

Tried the challenge today.

Saw your post and decided to try again myself. Time isn't my problem any more, and fuel has never been the problem, but I keep losing too much energy in the atmosphere and am not able to make it to the base.

Have to try again.

Good luck on your next try.