InSight -- Mars Lander


(Laura) #1

@Homeschool_Forum

I must not read science news enough because I just found out there’s a lander set to touch down on Mars tomorrow afternoon. Sharing in case it might be of interest in your homes too – I think we’ll try to watch it on NASA TV: https://mars.nasa.gov/insight/timeline/landing/watch-online/?fbclid=IwAR0PntHWMpfhTbcZIrAXzsivTBzpk-Dy30XdgwXcaJKw1-ZxuEdu_RAtgOI

There’s also a neat cartoon on the Oatmeal with some more info:


(Randy) #2

Thank you for the neat comic strip! I had no idea of this, either. I’m going to share with my kids.


(Mervin Bitikofer) #3

Cool cartoon introduction! I’ll quibble with them on one point: they say "It’ll decelerate from 13000 mph to 1000 mph, pulling about 12 'g’s in two minutes.

Actually the average acceleration over two minutes for that would be around 45 m/s^2 which is about 4.5 g. So either one or more of their numbers is wrong, or else (and this is quite likely), the acceleration might briefly peak out at 12 g at some point during that two minutes, but only very briefly if the average of ~4 to 5 g is to be accurate for the entire interval, the rest of which would have to be spent at less than 4 g.

So a 70 kg human would only weight about 3200 Newtons (~700 lbs) instead of the crushing 1800 lbs they indicate.

Click here for a highly scientific depiction of what such hyper-gravity might feel like. [Warning - there may be one or two slight scientific inaccuracies in this depiction too.]


(Laura) #4

Thanks for the clarification! I am sometimes skeptical of whether a popular, generally non-scientific publication can accurately describe something like that, so I’m glad there are people here who can critique the math because that is not my department. :wink:


(Mervin Bitikofer) #5

Well, I may not be that many steps ahead of you actually, since I’m at the mercy of the published numbers too. I notice that the press person Nasa has narrating the ‘pre-event’ also is giving conflicting numbers. He states 13,000 mph while the captioning at the bottom says 16,000 mph; but neither of those numbers will be close to satisfactory trying to reconcile the whopping “12 G” deceleration that he claims will be happening for the entire two minutes! In order for that to happen, the initial speed would have to be over 14,700 m/s (~33,000 mph!). What seems more likely to me is that the engineers delivering these figures actually shared them in meters per second, but the popular press changed it to mph not knowing or caring about the difference. [or it just briefly peaks out at 12g]. We’ll hope the engineers actually doing the work kept it straight this time, though!


#6

Isn’t there a famous failure caused by the engineers not keeping the difference straight?


(Mervin Bitikofer) #7

Yep. The Mars Climate Orbiter, almost 20 years ago now was lost due to a failure to convert.


(Joshua Hedlund) #8

Touchdown was a success!

Now I need to find a good clip/summary to show my 5-year-old tonight…


(Laura) #9

We really enjoyed watching – not the kind of “touchdowns” I’m used to celebrating, but even more interesting and impactful – you could see the intensity on people’s faces.