[Lex Computer & Tech Group/LCTG] How did they do it

Wed Jul 5 20:27:31 PDT 2023

I don’t think so, Stan.  Per Wikipedia, Hubble was finally launched in 1990, but its main mirror had been ground incorrectly, resulting in spherical aberrationthat compromised the telescope's capabilities. The optics were corrected to their intended quality by a servicing mission in 1993.

I doubt that spherical aberration would have been the primary result of a metric-English foul-up..
    Mike Alexander

Sent from Yahoo Mail for iPhone

On Wednesday, July 5, 2023, 10:17 PM, David Lees <joeoptics at gmail.com> wrote:

No it was an incorrectly manufactured mirror.  Nothing to do with units.  Radius of curvature was in error and they never did an end to end system test before launching it.  Interesting that a Lexington based company, Itek out on McGuire Rd for those who remember, proposed a full system test.  But for political reasons the contract went to Perkin Elmer in Connecticut.
H

David Lees 
>From Pixel 6 Pro
On Wed, Jul 5, 2023, 9:33 PM Stan Rose <stan_rose at alum.mit.edu> wrote:

Wasn't the original Hubble mirror problem also a metric-English error?
On Wed, Jul 5, 2023, 7:27 PM George Gamota <ggamota at stma-llc.com> wrote:

There was this Mars mission where the scientists used metric and engineers used English. The spacecraft went millions of miles of course.

From: LCTG <lctg-bounces+ggamota=stma-llc.com at lists.toku.us> On Behalf Of Ted Kochanski
Sent: Wednesday, July 5, 2023 6:15 PM
To: David Lees <joeoptics at gmail.com>
Cc: George Gamota <ggamota at gmail.com>; Lexington Computer Group New Address Distribution <LCTG at lists.toku.us>
Subject: Re: [Lex Computer & Tech Group/LCTG] How did they do it

Depends on the system which is involved

[aka Where is AI when you really need it]

A while back an Air Canada 767 headed for Edmonton Alberta had to do an emergency [no engine power] landing at a former [WW2-Cold War vintage CRAF base in Gimli Manitoba] -- Google or Wikipedia the "Gimli Glider"

While the whole incident was complicated by electronic embedded system failures, as well as procedural failures -- ultimately the "crash landing" resulted from a fuel load

entered into the flight control computer in kgs but using the measurement of the fuel load in lbs -- when they took off from Montreal via Ottawa enroute to Edmonton 

Somewhere in western Ontario they discovered that they had no fuel left -- and their engines shut down causing the plane to lose primary and backup hydraulic power 

and most of the electrical power as well. The loss of primary electrical power led to the loss of the Mode S Transponder causing great grief in the en-route Air Traffic Control 

Luckily -- The 767 came equipped with a ram-air turbine to drive an emergency hydraulic pump -- but this depended on the plane maintaining typical cruising speed

As they approached Gimli things didn't look too promising.

However -- There was manifold mostly accidental good news:  

the pilot was an experienced glider pilot

his co-pilot had flown out of the Gimli air base when he was in the CRAF.  

Lacking full hydraulic power the nose landing gear failed to fully descend and lock into place.  

Finally, and improbably the old airbase had been converted to a motorsports park [which was if use by drag racers used to dealing with fires] with a guardrail running down the centere of the former runway

[from the wiki article]

"As soon as the wheels touched down on the runway, Pearson [767 pilot] braked hard, skidding and promptly blowing out two of the aircraft's tires. The unlocked nose wheel collapsed and was forced back into its well, causing the aircraft's nose to slam into, bounce off, and then scrape along the ground. This additional friction helped to slow the airplane and kept it from crashing into the crowds surrounding the runway. Pearson applied extra right brake, which caused the main landing gear to straddle the guardrail.  Air Canada Flight 143 came to a final stop on the ground 17 minutes after running out of fuel
No serious injuries occurred among the 61 passengers or the people on the ground. As the aircraft's nose had collapsed onto the ground, its tail was elevated, so some minor injuries happened when passengers exited the aircraft via the rear slides, which were not sufficiently long to accommodate the increased height. A minor fire in the nose area was extinguished by racers and course workers equipped with portable fire extinguishers.

So sometimes even if you don't know your kgs from your feet or whatever -- you may still luck-out

Ted

On Wed, Jul 5, 2023 at 5:30 PM David Lees <joeoptics at gmail.com> wrote:

Yea, the metric - English units disaster.  Why metric units should always be used unless you are buying beer 😜

https://www.popularmechanics.com/space/moon-mars/news/a28632/the-dumb-mistake-that-doomed-a-mars-probe-in-1999/

On Wed, Jul 5, 2023, 4:06 PM Ted Kochanski <tedpkphd at gmail.com> wrote:

All,

Remember -- Mars has a tendency of inducing conversion errors 

Google for yourself how many of these

Ted

On Wed, Jul 5, 2023 at 3:59 PM George Gamota <ggamota at gmail.com> wrote:

You guys are right. Need stronger glasses :-) 

Sent from my iPhone

On Jul 5, 2023, at 2:51 PM, Dick Miller <TheMillers at millermicro.com> wrote:

 George, it will take more than a century for that rover to travel that distance. That is, if the likelihood of mechanical breakdown - or a Martian monster - doesn't come first.

It has traveled about 1.2 miles so far. In the article you cited, those were American decimal points, not European ones.

Cheers from
--Dick Miller, Partner, MMS <TheMillers at millermicro.com> 

Sent from an awesome, inexpensive, non-proprietary, no-lock-in, no-bloatware, virus-resistant, free open-source software, Linux PC - with Ubuntu-Unity 23.04 and Fotoxx 23.50.

On 7/5/23 14:15, Donald Cooke wrote:

That's a long way. Wikipedia has another opinion, Meters, not Kilometers: 

<image.png>

Don Cooke   #523  603.219.9259

On Wed, Jul 5, 2023 at 10:57 AM <ggamota at gmail.com> wrote:

I just saw that  the Chinese rover on Mars traveled over 1, 100 miles in one year. Seems like they figured out a way to travel autonomously. 

Any thoughts?

George

The Zhurong rover has operated on the surface of Mars for over a year since it deployed on May 22nd, 2021. Before the rover suspended operations on May 20, 2022, due to the onset of winter and the approach of seasonal sandstorms, Zhurong managed to traverse a total distance of 1.921 km (1.194 mi).

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David Lees 
>From Pixel 6 Pro

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