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I am now in the third week of my annual February birthday fund-raising drive. The first two weeks were good, but not record-setting.


There are still two weeks left in this campaign however. If you have been a regular reader and a fan of my work and have not yet donated or subscribed, please consider doing so. I take no ads, I keep the website clean from pop-ups and annoying demands (most of the time). Thus, I depend entirely on my readers to support me. Though this means I am sacrificing some income, it also means that I remain entirely independent from outside pressure. By depending solely on donations and subscriptions from my readers, no one can threaten me with censorship. You don't like what I write, you can simply go elsewhere.


You can support me either by giving a one-time contribution or a regular subscription. There are five ways of doing so:


1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.


2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.

3. A Paypal Donation:

4. A Paypal subscription:

5. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

Curiosity’s damaged wheels continue to appear stable despite the rough Martian terrain

A new look at Curiosity's worst wheel
To see the original images, go here and here.

The rover Curiosity on Mars has for more than two years been traveling across a very rocky and rough terrain as it climbs higher and higher on Mount Sharp inside Gale Crater. Since the rover’s wheels experienced far more damage than expected early in its mission, when it was on the floor of the crater where the terrain was not as severe, engineers have adopted a whole range of techniques to try to reduce any further damage.

First, they increased the safety margins on the software that guides Curiosity. It picks its way very carefully through the rocks, and stops immediately if it finds itself crossing terrain that is too rough.

Second, the science team does a photo survey of the wheels after every kilometer of travel. The two pictures to the right compare the damage on the rover’s most damaged wheel, with an image from the previous survey on top and the most recent image, taken yesterday, on the bottom. I have numbered the same treads, called grousers, in the two images to make it easier to compare them.

As you can see, it does not appear as if the damage has increased in the 210 sols or seven months of travel since the last survey. This wheel looks bad, but it is the worst wheel on the rover, and the strategies that the engineering team adopted years ago to reduce further damage continue to work, even as Curiosity traverses some very rough ground.

The software requires the rover to travel shorter distances in each drive when the ground is this rough, but the consequence is that it will last much longer, and thus have a better chance of reaching higher elevations on Mount Sharp.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.

The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News

Readers: the rules for commenting!


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