[X] My Assistant

[Gerald]

Yeah, soil investigations would be an XM sort of thing. But it might not pencil out.

With an idealized tilt angle of ~53° between the pointing of the mole and the surface normal, a 5 m teather would still be long enough to reach a nominal 3 m depth required to accomplish the primary science objective (take the triangle defined by the Pythagorean triple 3³+4²=5²).
Within those constraints, this would presumably maximize the friction between the mole and the soil beneath induced by the weight of the mole.
So, this approach would probably feasible without an entirely new proposal.

[mcaplinger]

With an idealized tilt angle of ~53° between the pointing of the mole and the surface normal...

How could the tilt of the mole could be controlled? I'm not aware of any way to do this.

[Gerald]

First, it's required that the mole bounces back and partially out of the ground like it happened once already.
If we assume that this will happen a second time, I see two approaches:
- A risky one, use the scoop to tilt the mole. Ensure that the force doesn't damage the mole.
- A less risky, but more time-consuming approach: First dig a ramp with the scoop, then tilt the mole, cover it with soil, use the scoop to initially push onto the soil cover when hammering. Alternatively use the scoop to prevent the mole from bouncing like demonstrated already.

If the risky approach fails and the mole ends up horizontally on the surface, the scoop will be needed to move the mole, to dig a ramp, to move the mole to the ramp, and to cover it with soil.

If the mole remains stuck and neither forward nor backward motion is possible by hammering, we'll have a less trivial issue. I doubt that pulling at the teather would be an option. Scooping deep enough to free the mole will be a challenge. Scooping just to the mole might be feasible. This might change the behaviour of the mole. But it also bears a significant risk to be a dead-end.

[JRehling]

The vigorous interventions you describe, Gerald, are not supported by the level of interactivity and power levels on the lander. This would be the kind of thing someone might do with one of those arcade games where you pull the toy out with a crane, but Mars is 6 light minutes away and getting farther. A small action with the arm produces no feedback regarding the result until a photo would be taken and sent back to Earth. If the arm is in the way of the photo, it would need to be moved, then moved back. We might need for an orbiter to revolve into position to receive the photo, then transmit it to Earth when DSN bandwidth is available. And the power levels on the lander are at a premium, so they were looking at a 14-day cycle between interventions, 7 days in the better case.

This is not like building a model ship. It's like trying to get a trained dog to build a model ship while you yell commands through a windowless door.

[Explorer1]

Unfortunately, just because something is physically possible, even with the Earth-based test model, does not mean it can be practically replicated on Mars.
If this was the first 90 sols of the mission in terms of power generation, and there were no other spacecraft requiring data relay and DSN time, (and we already knew the soil properties ahead of time!), things might be different. I know from OSIRIS-REx's drama with the sample collection that there are extenuating circumstances where emergency DSN time can be given, but HP3 is not like that. Add of course, February will be very busy again on the red planet.
If the January hammering does not work, it may be time to throw in the towel. Mars hasn't chalked up a win in a few years, after all....

[Gerald]

I mostly agree with what you say. But if the addressed science is considered relevant and required to be done, then we have to compare those time and expenses with the time and expenses needed for designing, proposing, building, testing, landing and operating a backup mission.
I'd presume that DSN will communicate with the orbiters, and a few commands more each week or so to inSight won't make a big difference for the total traffic with Mars.
All I can do is sketching some options. Making the decisions is someone else's job.

[JRehling]

I don't know how close Insight is to end-of-life threats, but with power in short supply, and with other Mars missions having failed critically when power ran out, efforts with the mole draw from another important budget – the diminishing power on the lander – as well as human labor and operations expense. The seismometer is working well and it would be a shame to have that part of the mission terminate earlier than it had to because of failed efforts to get the mole going.

I hope that we'll get a clearing event and maybe the lander could work for another entire martian year, but this is northern winter now, and winter is the killer of solar-powered surface elements.

[PaulH51]

Arm activity above the mole on Sol 734 (December 20. 2020)
Animated GIF

[djellison]

efforts with the mole draw from another important budget – the diminishing power on the lander

I would argue this is the only budget that actually matters. The others are negotiable. This one is not.

[Gerald]

Power generation by the solar arrays is described in this paper.
Ancillary sc data are provided here.
The latest currently available data set is of Sol 569. Data are only partially recorded.
Here an attempt to plot a diagram:

The maximum current within the data set is roughly 0.1 A.
The portion I don't yet understand is the factor of 11,000 Vh in Figure 4 of the above paper.
If we would just use that factor, we would get about 1 kWh for Sol 569. But the factor may depend on the duration of the daily sunshine.
Unfortunately, I don't have access to more recent telemetry.

More information about InSight power management is provided in this paper.

The power requirement of SEIS is described in this paper.
The heaters seem to consume up to 1.5 W. The instrument usually requires about 5.9 W, see subsection 4.1.9, but can be up to 11.83 W, see Table 5.
So, 250 Wh per day should be sufficient to operate SEIS continuously.

In addition, the main system, and communication requires power. I didn't yet find out how much.
And there will be some power loss by the batteries.

HP³ is described in this paper. See Table 1 for information about a 4h hammering activity. If I summed up correctly, it's 367 Wh.

Thus far my attempt of today to provide some, but a still incomplete, basis for further considerations.

[mcaplinger]

Thus far my attempt of today to provide some, but a still incomplete, basis for further considerations.

I think we can be confident that the team has thought about additional activities that could be tried to recover some of the HP3 science, and they are in a much better position than we are to evaluate what's possible and what's not.

[rlorenz]

Power generation by the solar arrays is described in this paper.
The maximum current within the data set is roughly 0.1 A.
The portion I don't yet understand is the factor of 11,000 Vh in Figure 4 of the above paper.
If we would just use that factor, we would get about 1 kWh for Sol 569. But the factor may depend on the duration of the daily sunshine.

That is correct - about 1000 W-hr per Sol. (Note that the length of day hardly varies at the equator)
I'm glad the paper was of interest.
Ralph

[Gerald]

Thanks a lot, Ralph!
Your paper helps significantly to understand the InSight probe, and how to use housekeeping data to retrieve additional science!

[Mars Attack]

Thanks a lot, Ralph!
Your paper helps significantly to understand the InSight probe, and how to use housekeeping data to retrieve additional science!

The tether has a substantial tear in it, about 20% across. May not be usable anymore.

[PaulH51]

The tether has a substantial tear in it, about 20% across. May not be usable anymore.

I'm guessing you're referring to this? Let's hope that it's just a mark left by the scoop rather than a tear!