Meithan

Dammit, missed it. I'm on the road right now. Does anyone have a link so I can watch it later?

Posted just now on MOM's Facebook page: Congratulations! One step closer to Mars.

Fantastic! Can't wait to see new images from the lunar surface!

I suppose you were posting about MOM's upcoming TCM, Tech Support? That's a bad link. Edit: there, image displays correctly now.

Thanks a bunch for the reply, definitely makes sense. This was just a test rocket; the top pods were to simulate 15 tons of weight. But it's good to know what conditions can set MJ off.

Hi. Is this the place to report bugs? Last night I was getting incorrect delta-v values. Here's a picture of the test rocket: As you can see, the staging detected by MJ is a bit weird. And the total delta-v reported is off by a factor of ~two. Computing the delta-v manually, I get somewhere between 2100 (atmo) and 2500 m/s (vacuum). And indeed, when launching that rocket, after I run out of fuel MJ reports a "delta-v expended" of 2310 m/s. What's weirder is that the burntime seems to be correct; it's just the delta-v figure that's off. I redownloaded MJ's last version just to be sure, and it still calculates it incorrectly. Thanks.

(Source: http://www.spaceflight101.com/change-3-mission-updates.html) And the trajectory and landing time were also chosen so that China is looking at the event, facilitating tracking. Nice work on orbit planning, guys.

So? Any news on the orbital insertion?

I just had to sit an exam, and in order to kill time I did the calculations on a sheet of paper. Assuming that the payload is injected into a standard GTO (385 by 35,780 km, 20.5°), it requires about 1660 m/s to do the combined inclination change + circularization at apogee. This is less than the 1800 m/s mentioned above, so I might be wrong here. If, instead, the payload is initially injected into a supersynchronous 385 x 80,000 km, 20.5° orbit, it requires about 1014 m/s to do the combined inclination change + periapsis raise at apogee, and then 491 m/s for the circularization. That's a total of 1505 m/s. While it's still cheaper, the difference is not that large, but I suspect I made a mistake in the first calculation. Will recheck.

But I'd calculate the delta-v requirements for the part of the journey carried out by the payload, SES-8 in this case. That is, I'd compare two options: Option A: launch rocket puts payload into standard GTO with a 36,000 km apogee. Payload then performs a circularization and inclination change burn at apogee. Option B: launch rocket puts payload into supersynchronous GTO, with the apogee at 80,000 km. Payload performs an inclination change and periapsis raise (to GEO altitude) burn at apogee. Then, at perigee, payload performs a circularization burn (the standard bielliptic). Also one has to keep in mind that burns can combine simultaneously change in periapsis/apoapsis and inclination, and that it's cheaper than doing separate burns. But I think SES-8 is scheduled to do something like 5 burns in order to reach final GEO.

Well, Cape Canaveral Air Force Station is at latitude 28.5°, so that's the minimum orbital inclination if you launched "straight". I think it's a good estimate of the inclination change required. Edit: also, this was reported on spaceflight101: Edit 2: more details:

Successful rocket launches make me so happy

Go SpaceX!

Please do, sir, if it's not too much trouble.

Chang'e 3 launch and trans-lunar injection was a complete success. Congratulations, China!

Argh, missed it! Launch was successful, then? I see the last stage is still burning.

Great article indeed. I kinda feel people like Elon Musk are trying to go against this stagnation. But the thing is he had (economic) success before he started taking big risks in innovation.

Stupid ignitors. He also tweeted this a bit earlier: So Monday, it seems.

Congratulations, ISRO!

"Just crossed the last perigee. Engine continues to fire as planned." It's looking good . Engine restart after so many days of inactivity was probably the most difficult part.

"10 minutes of firing completed. Performance normal so far. Liquid engine continues to fire as planned."

The discrepancy is small that it's hard to assess the cause. I've been developing an aerobraking simulator mod, and drag is where I still get slight discrepancies with MechJeb values and game results. Since drag depends on the square of velocity, small errors in velocity will translate into noticeable errors in drag, which in turn alter the calculated velocity, and so on. You might try switching to a higher-order numerical solver. If I understand your code correctly, you're using a first-order Euler method right now. It's not the best of methods. A simple option is the midpoint method. It's quite simple: first use the Euler method to estimate values for airspeed and altitude half a timestep ahead, and then use those "midpoint" values to obtain the new airspeed and altitude. You'll need to compute acceleration twice so you might want to define a function that does just that based on altitude and airspeed values.

So, all set for Trans-Mars Injection?

I stand corrected. I think I only watched the v1.1 launch and one of the CRS launches (I might have watched only the second attempt). So it has been a bumpy road it seems. But I think that, all things considered, they've been very successful so far, and these difficulties are normal for a rocket company that's just starting out (with most hardware designed from the ground up, one must add). Where are you getting all this info, by the way? Just thorough Google search?

A report by SpaceFlightNow says the Chang'e 3 mission might liftoff as early as next Sunday (Dec 1st), based on reports of a notice to airmen issued for the region: Chinese moon lander on the verge of launch That's a maybe. No official launch date yet.