Mars inSight Mission

[Eric Mc]

Just a heads up to remind people that this mission is scheduled to land on Mars on November 26.

[Eric Mc]

They aren't looking for dramatic scenery or spectacular geology on this mission. They want a nice smooth surface that they can set down on and do some serious drilling. It will be the deepest drilling done on another planetary body since the Apollo astronauts took core samples on the moon.

[Eric Mc]

NASA briefing here. It's best advised to ignore the typically moronic utterances in the comments section.

https://www.youtube.com/watch?v=nzBkCVGwWsg

[Eric Mc]

No need for a sky crane on this one as it is a relatively small lander.

[Eric Mc]

Not if you only look at NASA's missions. NASA has a pretty good success rate. It's the other agencies that have fared less well.

[Eric Mc]

InSight is actually a developed version of the Mars Phoenix lander which successfully landed on Mars back in 2008. It uses the basic "bus" of the Phoenix but with a different set of experiments on board. Phoenix was designed to sample the Mars environment near its polar regions. InSight will be landing closer to the equator and is primarilly a geological and geophysical mission.

NASA sent its first probes to Mars in 1964, so it has a very long track record of sending missions to the planet.
From memory,the only NASA Mars lander that failed during the landing phase was Mars Polar Lander back in 1999. All their other landers have made it safely on to the surface -

Viking 1
Viking 2
Mars Pathfinder
Phoenix
Opportunity
Spirit
Curiosity

[Eric Mc]

andy_s said:

Bump

I hope that's not a prediction.

[Eric Mc]

I have great confidence in JPL managed missions. They really do know what they are doing.

[Eric Mc]

Agreed. They have a great track record - although their earliest attempts at space probes were not that successful. At one point NASA was seriously considering giving up on them. How times changed.

[Eric Mc]

hidetheelephants said:

Presumably the turnaround was Voyager? That seemed to set the tone for their deep space stuff since then, and still nominally operational 4 decades later.

No, a bit earlier.

NASA started using the JPL almost as soon as NASA was set up in 1958. Their initial probes were aimed at the moon and were extremely unsuccessful. The first really major project they were given (1961) was the Ranger series but every single one of them was a failure until they got to Ranger 7 - which impacted the moon in 1964. It was because of the Ranger problems that NASA became a bit disillusioned with the JPL. However, in the same period (1962) they did have a successful Venus flyby (Mariner 2) and that encouraged NASA to keep giving them second and third chances. In 1965 they had a successful flyby of Mars (Mariner 4).

At this time, JPL policy was to build two of each spacecraft because it was expected that at least one of them would fail at some point - and that was borne out by many of these early probes.

Ranger - lunar probe - Rangers 1 to 6 failures. 7 to 9 successful (1961 to 1965)
Mariner 1 and 2 - Venus flybys - 1 a failure, 2 successful (1962)
Mariner 3 and 4 - Mars flyby - 3 a failure, 4 successful (1964)
Mariner 5 - Venus flyby - successful (1964)
Mariner 6 and 7 - Mars flybys - both successful (1969)
Mariner 8 and 9 - Mars orbit - 8 a failure and 9 a success (1971-72)

Those missions cover the period 1961 to 1971. From 1971 onwards, the JPL designed missions became a lot more reliable and the successes now outweigh the failures by quite a margin.

[Eric Mc]

Looks pretty close. Although Mars is predominately red (both ground and sky), there are permutations and you can even get blue skies on occasions.

[Eric Mc]

Not TOO lucky. This mission is not looking for interesting scenery or interesting surface features. Its mission is to explore "what lies beneath" so the priority was to get down safely. They purposely picked an area that was known to be flat and fairly smooth. However, the lander is small and not that high off the ground. As a result, even a small boulder could have caused an issue - and even the best resolution possible from the various Mars orbiters would not be good enough to pick out a boulder that could have damaged or overturned the lander.

It was very similar to the problems JPL faced back in 1976 with selecting landing sites for the two Viking landers. However, we have much better images of Mars now than we did in 1976 so the "gamble" of choosing where to land was a lot less risky than 42 years ago.

[Eric Mc]

Does such a device exist?

There are always loads of compromises and payoffs when designing these craft - especially when it comes to keeping weight down.

So far no JPL Mars landers (since 1976) have been turned over by a rock.

[Eric Mc]

johnxjsc1985 said:

I sat in school as a young boy as the wheeled out the TV to watch the Apollo missions and that seemed to be the ultimate achievement of mankind but this stuff is just incredible. I have no idea how they communicate over this distance and co-ordinate and programme the landings. It must be incredible to be part of this "event" I am simply in awe of all of them. The speed, acceleration and progress made in Space travel is just incredible and who knows where we might be in just 20 years time.

To be fair, inSight is not that cutting edge. The technique they used for landing was pretty much what was used for the Vikings 42 years ago. The spacecraft itself is heavilly based on Mars Phoenix which landed on Mars in 2008.

One of the experiments carried on board is a heat flow experiment - which is pretty much identical in principle to the heat flow experiments carried out by the Apollo astronauts on the moon in 1971 and 1972. The difference is that the drill has to work itself. The Apollo drill was a hand operated device.

[Eric Mc]

MartG said:

Surface roughness does affect radar return signals, but I suspect the device carried by the lander is a simple altimeter

I'd say it isn't that different to the reversing sensor system on modern cars.

[Eric Mc]

But at what cost in weight penalties? The equipment itself would be heavier plus the need to carry additional fuel and (possibly) thrusters to allow all that hovering and manoeuvering.

I'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.

[Eric Mc]

RizzoTheRat said:

They mentioned on the live stream that the radar was a modified version of the one in the F16, but presumably they mean the F16's radar altimeter not its main radar.

Maybe they expect to have to shoot down some hostile Martians (or a rival lander from some other space agency)

[Eric Mc]

MartG said:

Eric Mc said:

But at what cost in weight penalties? The equipment itself would be heavier plus the need to carry additional fuel and (possibly) thrusters to allow all that hovering and manoeuvering.

I'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.

The reduction in risk of losing the entire mission due to an inconveniently placed rock could be worth it - maybe they've just been lucky so far

I really don't think they would be that careless with such missions. I kind of go with the theory that they do know how to do these things. It may be a mad theory, but there ya go.

[Eric Mc]

The craft just doesn't have the fuel capacity to allow it to dick about in the hover. It really is a bit of a gamble getting these things down. However, they did select a fairly smooth area for this mission and the images they have of potential landing sites are way better than what they had to go on decades ago - so far less of a gamble than in the days of Viking.

[Eric Mc]

JPL should always consult the experts on PH first - or so it seems.