In the last 24 hours, we have seen the culmination of two ambitious small lunar missions This is telemetry from Jax’s slim, smart Lander for investigating the moon and it softly landed successfully on the moon.
However, afterwards, it appears that it may have rolled and not assumed its correct Landing orientation and as a result, it’s not getting power to its solar panels If you look over to the right, it appears as if the orientation of the spacecraft ends up in a flamy end up orientation, as some people like to say, and so right away, congratulations to Japan for being the fifth Nation to successfully put a Lander on the surface of the Moon Good job, however.
It’s very clear that the power is slowly draining from the Lander and at this point, you can’t go off and celebrate; you’re going to have to work your asses off until you get all the data out of that thing and it finally goes to sleep.
Jan 19th 2024 | TOKYO
So, rewinding about 4 months ago, the spacecraft launched from Tashamama Space Center on board an H2 rocket. It was paired with the prism of the Space Telescope, which is an X-ray spectrograph. You know how capable the telescope is.
Now, from there, it had to go into a long, low-energy orbit to bring it toward the moon. This is one of those fancy astrodynamics out to one of the sun-Earth range points, and while it’s balanced there, it brings its orbit up and then falls back towards the moon.
And entered lunar orbit While it was orbiting, it produced some images of the lunar surface. These were mainly engineering images that were supposed to test whether the hardware on board would work once you got to the surface of the moon. I mean, it’s, you know, PR value to show what the surface looks like.
So, after several months in space and finally getting to orbit the moon, it begins its breaking burn It approaches The Landing site from the south, and during various points in the landing, it rotates into a position that would allow it to scan the surface and then continue its burn It would stop at like 5 km, 500 m down to 50 m, do a landing scan to find the point where it was supposed to land safely, and then target towards that. Finally, just before landing, it was supposed to re-release its two Rovers, Lev1 and Lev2, and finally, it landed on its side.
It’s supposed to induce a bit of rotation just before touchdown so that it gracefully folds onto those wheels, but clearly, that’s not what happened in this case Now that the Rovers are both out on the surface, they of course have limited lifespan on their own we’ve got a little Hopper lev1 and that is that is can communicate directly with Earth The other one is this little spherical boy that can roll around, okay?
Image Credit: Reuters
So the landing site is around about here. There is a crater called Theopolis just to the north, and it’s really hard to tell from this map on Google Moon but if I hit I think a shift yep I can bring this down you can see there’s a bit of a slope there right now they wanted to have terrain that was sloping so there’s about a 10° slope at this particular location and that necessitated some well a slightly different Landing technique than most spacecraft use and so that’s presumably how they arrived at this technique as it gets very close to the surface.
It induces some Pitch attitude with the RC thrusters and then sort of hopefully gently wobbles back and forth on those feet so now can we figure out the orientation of the spacecraft based upon the Fantastic Telemetry display they offered so the spacecraft is approaching from the south the slow SL is sloping kind of downwards to the South and remember they intentionally clut Land close to lunar Dawn which means the sun is in the East and so in the display, you can see that the solar panels are aligned to the east but as it get closer to the surface it performs this rotation, so watch on the right side There’s this rotation attitude adjustment as the solar panels are now sort of turned over to the south side of the vehicle.
So based on my understanding of this orientation, the X display on the left is looking southward with a negative X going east and a positive X going west and the Y display is looking eastward with a negative y going north and a positive y going south So again, I’m running this at about four times the normal speed, but you’ll notice that it’s pausing at different altitudes to assess the surface of, you know, the landing area.
And make decisions about where it’s going to touch down Even though the Moon is only one and a quarter light seconds away, there’s enough of a delay there that you want this to be entirely autonomous other things to note are like at the bottom of the screen, you’ve got the two throttle meters showing how you how much power is being delivered to the main engines You’ve got 12 RCS thrusters being used there are three rotation meters (Omega Y, Omega Z, and Omega X) showing the attitude and the rotations.
That is going to be critical but I’m guessing the spacecraft only has gyros that measure the rate rather than the actual orientation so it’s having to add up these small rotations to figure out the orientation.
But one thing I notice, by the way, is that it’s coming down slightly off angle and that could well be that it’s doing that to null out some lateral velocity that it’s detected because you want this thing to hit with zero lateral velocity and the exact rotation that you have planned for.
That it you know assumes the correct position after settling and yeah from this display it’s not clear what zero altitudes is so based on this telemetry can we figure out whether the rotation was you know correct so we’re going to expect a pitch-over maneuver just before it touches down and we don’t see that what we see is a 3° pitch and a Min -4° yaw and yeah this is a freeze frame but the actual telemetry freezes for a good few seconds here and that’s not entirely unexpected when the spacecraft is rotating and the antenna patterns are pointing in different directions we expect a loss of telemetry.
As soon as it touched down measuring the video stream I saw about 8 Seconds of no telemetry, and then the next thing we saw was this ya the pitch rates are now off the scale Here there is a bit of a roll and you can see the thrusters are trying to compensate for all these three rotations so I think the spacecraft came down and touched the surface before it performed the powered pitchover maneuver for the actual Landing orientation Also, I think the direction of the yaw is consistent with a spacecraft moving eastwards across the surface which is what would have happened based upon its thruster orientation during the final descent.
Of course, this is all based on public telemetry, which could be wrong Also, summing sequential rotations from rate Gyros is prone to error but if this is something we can trust hypothetically, that would mean the solar panels are pointed away from the Sun they’re pointed westwards and that would explain why the spacecraft is slowly losing power but it does offer some hope because if this attitude is correct and the spacecraft is pointed flamy end up with the solar panels towards the west that means that the sun will eventually illuminate those solar panels perhaps in a week or even less.
And then we might have the spacecraft come back to life in some way and perhaps be able to get some imagery and you know of course we also have the Rovers on the surface which should be able to hop around and do their thing independently and maybe get some images to confirm this so I’m looking forward to seeing some images coming out of this again I consider this whole thing to be massive success for Japan great work so while we’re here talking about lunar Landers I think we should also talk about peragine astrobotics.
Para gr Lander launched on the Vulcan rocket was a massive success it successfully delivered the payloads to the correct orbit Unfortunately, as you probably heard the spacecraft encountered some problems soon after it h started lighting up its engine By the sound of things there was a helium pressurant valve which opened to pressurize the tanks and it did not close and somewhere in the system that resulted in the pressure increasing too much there was a break and that meant there was a propellant leak and this propellant leak subsequently caused the spacecraft to start spinning Soon after separation they were worried that they were going to run out of power.
Now they managed to orient the spacecraft correctly given this limited performance they of course at that point ruled out a moon landing and then over the next few days they progressively got more control the leak abated but the sort of small impulse from that leak over time was pushing the perig G of the orbit downwards and the spacecraft was going to return to Earth’s atmosphere.
So there was some great communication from astrobotic everybody was r for this Mission you we were seeing things go up we were seeing the problems get fixed them while they weren’t going to make it to the moon, they did make a point of trying to activate the payloads and those which were able to collect data in deep space they got some data back from that and while they did demonstrate the ability to maneuver the spacecraft even with a limited propellant available in the leak it was decided that they would drop the spacecraft into the atmosphere they won’t weren’t going to kick it around and leave it fly off into deep space and it ended up re-entering you know just uh well thousands of kilometers east of Australia I haven’t seen any imagery of the re-entry it is a long way from land.
So we didn’t expect it but we did see some telescope images from s2a systems that work on Space domain awareness showing the spacecraft descending and venting or possibly firing its engine I think it would make sense for them to fire the engine and reduce the am propellant on board as much as possible because that would reduce the mass reduce the ballistic coefficient and make sure that it burns up uh it’s more likely to burn up instead of leaving pieces landing on the surface astrobotic also shared this nice image of the earth as viewed from the spacecraft with the sun carefully well the spacecraft carefully maneuvered so that the sun was blocked behind that strut so that we could see you know the crescent of the earth.
So if you like these missions then you are in for a treat this year because we are looking forward to a bumper year of lunar Landers we are going to have intuitive machines launching their Nova Sea in May There’s going to be another one later in the year we’re expecting Blue Ghost Viper there are a whole lot of NASA commercial lunar payload services missions going to the lunar surface this year and hopefully some more of them will succeed.