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Scott “marsroverdriver” Maxwell
Works at Google
Attended University of Illinois at Urbana-Champaign
Lives in Pasadena, CA
45,829 followers|4,740,595 views


How much will NASA's SLS rocket and Orion crew vehicle cost to fly, you ask? Punchline: too much, and in particular, more than whatever they say now. I promise that it will arrive later, and cost more to fly, than whatever they're saying at this stage. The economic incentives of NASA contracts make that inevitable.

Anybody who wants to predict otherwise, I'm taking bets.
Production and operations costs of $2 billion or less annually would be manageable.
Scott Carpenter's profile photoDanny Kyllo's profile photoDean Calahan's profile photoScott “marsroverdriver” Maxwell's profile photo
+Dean Calahan I made the comment before blocking him, in the hope that G+ would send him the notification or email or whatever he has set up first.

Anyway, the comment is as much for our amusement as for his benefit. :-)
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Generally, when someone's main coping strategy isn't working, they do it harder. Then harder. Then way harder.

That seems to be what Trump is doing here. I'm not sure he knows any other tricks anyway, so I predict he'll just continue to spin up, more and more wildly, without apparent limit. People can go to ridiculous lengths before they actually switch strategies, if indeed they ever do.

<grabs popcorn>
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"Earthlike" is an awfully loose term. One of the most important criteria for a planet to be considered Earthlike, a cynic might say, is for the researcher or space agency announcing it to want media attention.

But I care almost nothing about that. I think it's amazing that we're seeing planets around other stars. This one orbits a star that's only about four light-years away -- close enough that there could, in principle, be a mission to it in your lifetime. That's spectacular, whether the planet in question is Earthlike or not.

Via +Andres Soolo​.
Not like Earth

On Thursday, NASA will announce a planet orbiting Proxima Centauri - the star closest to our Sun, 4.24 light years away.   They're trying to make this planet sound like Earth... and that's cool.   But I'll tell you some ways it's got to be different.

Mainly, Proxima Centauri is really different from our Sun! 

It's a red dwarf.   It puts out just only 0.17% as much energy as our Sun.  So any planet with liquid water must be close to this star.

And because it's cooler than the Sun, Proxima Centauri mainly puts out infrared light - in other words, heat radiation.   Its visible luminosity is only 0.005% that of our Sun!

So if you were on a planet as warm as our Earth orbiting Proxima Centauri, it would look very dim - about 3% as bright as our Sun.

Of course, if there's life on this planet, it would probably evolve to see infrared. 

But there's a more serious problem.  Proxima Centauri sometimes puts out big flares, with lots of X-rays!  That's not very nice.

Why does a wimpy little red dwarf have bigger flares than the Sun?

The Sun has a core where fusion happens, and helium produced down in the core mainly stays there.   A red dwarf doesn't have a core: it's fully convective.  In other words, heat moves through the star not by radiation, but by hot gas actually moving up to the surface. 

All this ionized gas moving around makes big magnetic fields.  The magnetic field lines get twisted up and sometimes explode out in flares!  These flares get so hot that they emit X-rays.  That's very  hot.

The same thing happens in our Sun but on a smaller scale.  Even on a calm day, Proxima Centauri puts out as much X-ray energy as our Sun.  But when a big flare occurs, it can put out 10 times more.   This happens pretty often. 

So: any "Earth-like" planet orbiting this star will be a lot closer than the Earth is to our Sun, and get a lot more X-rays. 

Puzzle 1.  Use what I've told you to estimate how much closer a planet must be, to be at the same temperature as the Earth.

Puzzle 2.  Estimate how much more X-rays it will get.

On top of this, Proxima Centauri could be part of a triple star system!

The closest neighboring stars, Alpha Centauri A and B, orbit each other every 80 years. One is a bit bigger than the Sun, the other a bit smaller. They orbit in a fairly eccentric ellipse. At their closest, their distance is like the distance from Saturn to the Sun. At their farthest, it’s more like the distance from Pluto to the Sun.

Proxima Centauri is fairly far from both: a quarter of a light year away. That’s about 350 times the distance from Pluto to the Sun! We’re not even sure Proxima Centauri is gravitationally bound to the other stars. If it is, its orbital period could easily exceed 500,000 years.

On the bright side, Proxima Centauri will last a lot longer than our Sun. As it ages, it will get smaller and hotter, gradually changing from red to blue.  After about four trillion years it will grow to 2.5% of the Sun's luminosity.   When its hydrogen is exhausted, it will then become a white dwarf, without ever puffing out into a red giant like our Sun.

So, any planet orbiting this star will be a weirdly different world.  But if we ever get there, we could stay for trillions of years, long after our Sun has become a red giant, roasting life on Earth.

For rumors of NASA's announcement, see this:

For more on Proxima Centauri, try this:

45 comments on original post
Scott “marsroverdriver” Maxwell's profile photoTobias Thierer's profile photo
+Scott Maxwell​ oh, I wasn't suggesting that it wouldn't be worthwhile if it exceeded a human lifespan. Work on a probe that sends data from another star system long after my death? - sign me up! :)
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Mars is getting real, yo: SpaceX's Mars-rocket engine is testing in Texas. In the launch configuration, with nine of them yoked together, they'll provide three Space Shuttles' worth of thrust.

(That is so a unit. :-P)
If a full-scale Raptor engine is undergoing tests, the company is progressing to Mars.
St. Eve's profile photoScott “marsroverdriver” Maxwell's profile phototim hem's profile photo
tim hem
k, thanks scott - i assumed they may at least have data collection interest in the ride that be worth paying for...good to hear that is the case
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Matt Jeffries (of "Jeffries tubes" fame!) designed the original, and still the most beautiful, Starship Enterprise. And here he tells you how.
When Matt Jefferies set about creating the iconic starship in 1964, he had little to go by except Gene Roddenberry’s vision.
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I remember the books that came out with the series.

They went over the entire design process - spock's ears and makeup, Bones' medical gear, phaser configurations, the works.

Apparently one of the earliest 'goofs' came from getting Nimoy's makeup correct for TV. The Color Timer thought there was a problem with his skin tint, since it kept coming out greenish. So the Timer would adjust the print so he had normal flesh tint. Roddenbery & Co. forgot to include that in the processing instructions.

The transport disks were old lighting Fresnel lenses, that came from the "Forbidden Planet" set (and later used on ST:NG). McCoy's instruments were actually salt and pepper shakers.

I've noticed too, that some of the sound effects on TOS, were first used in various B-Grade sci-fi movies from the 50's and early 60's too.
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"Why spend money on space when there are starving people right here on Earth?" I've spent some time developing answers to this question, and now I have a new one: because you can use satellite data to fight poverty.
In regions where data about people's welfare is expensive to collect, or not publicly available, international organizations are increasingly turning to satellite images to fill in gaps.
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I wish the media would stop using the word "debate" in the context of "climate change debate," "evolution debate," etc. The word "debate" suggests that there are two[1] sides, which is not true in any meaningful sense there.

What word would be good to replace it? My candidate is "tantrum," as in, "Pat Robertson threw another evolution tantrum today."

[1] Or more. But you see my point.
Scott Carpenter's profile photoDor Kleiman (configurator)'s profile photo
First though, you must stop using theory correctly, as that implies the same other side to those ignoramuses. 
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What do you do when you want to extend an eclipse to study it better, but there aren't spacecraft like SOHO that can effectively make eclipses of their own? You climb into a supersonic jet and race along the eclipse's path, of course. As these brilliant scientists did in 1973.
The History of When Concorde Chased ‘the Longest Total Solar Eclipse of a Lifetime’

The Concorde, sadly, is no more. But its story will survive as an engineering marvel of its day and ultimately a plane of legend. Notably in the early 1970s, even prior to the airplane being used for passenger service, it was being used for a once in blue moon opportunity – or in this case a black moon opportunity, as a prototype Concorde was used to chase an eclipse for an astounding 74 minutes of observation! Motherboard have the full story.

…in 1973, a small group of astronomers from around the globe had a secret weapon for seeing a longer eclipse than ever before: a prototype Concorde, capable of chasing the eclipse across the Earth at twice the speed of sound.

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To my surprise, it looks like another company might beat +Planetary Resources​ to the asteroid-mining punch.
Deep Space Industries will build a water-powered spacecraft to search for resources.
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+Nina Lanza​ wrote a great article on discovering manganese on Mars and what that tells us about the red planet's history of oxygen.
We never expected to find manganese oxides on Martian rocks, but we did. What that says about Mars' former atmosphere.
hal mcfarlane's profile photoTom Nathe's profile photoJ Abdul's profile photoScott “marsroverdriver” Maxwell's profile photo
+J Abdul Here is one of many places online where you can find a detailed explanation of why the arm is not in the selfie, complete with a video illustrating the entire process:
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Astronomy is one of the few scientific fields where amateurs can make contributions of such magnitude. Which is one reason why I've been noodling around the idea of building my own Raspberry Pi-based star-tracking telescopic camera ....
Regular folks armed with the Internet are pushing sky science into fast forward.
James Marsh's profile photoScott “marsroverdriver” Maxwell's profile photo
+James Marsh Nope, not at all. But please try to bring more substance (and not so much with the SHOUTING) to your future comments. I don't like to block people, but if you're participating without contributing, I will.
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  • University of Illinois at Urbana-Champaign
    Computer Science
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  • X-Plane 10 Flight Simulator
I'm a pretty big wheel down at the cracker factory.
On a small red light in the night sky lives four hundred pounds of thinking metal sent from Earth.  Once upon a time, I told that metal what to do.

(Disclaimer: my opinions are mine, not my employer's.  Duh. :-)
Bragging rights
I fought cancer and won. I had a robot on another planet, and I drove it around and made it do stuff. I was a trending topic on Twitter. I wrote a book. I took a privacy case all the way to the Supreme Court. Now I keep Google up and running. But I'm just this guy, you know?
Site Reliability Engineer
  • Google
    Site Reliability Engineer, 2013 - present
  • JPL
    Mars Rover Driver Team Lead, 2013
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Pasadena, CA
Rocky Mount, NC - Seminole, FL - Greenville, NC - Champaign, IL
Public - a week ago
reviewed a week ago
Public - 3 weeks ago
reviewed 3 weeks ago
Public - a month ago
reviewed a month ago
15 reviews
Fast (roughly 10Mbps symmetric), free wi-fi. Unfailingly upbeat, pleasant, helpful staff. I slept great in the super-comfy bed; I was a little worried about their proximity to the freeway, but I couldn't hear it at all. I parked myself in the spacious lobby for a few hours the next day, well past checkout time, to work on my laptop, with zero complaints (and even the occasional helpful suggestion) from the staff. Breakfast was fine (and free), parking was good, and the price was (relatively speaking) low. My single complaint about the place was the shower. This can't possibly be the typical experience, but the amount of cold water coming from my shower varied with time, so that it went from boiling to comfortable to freezing and back, over and over. Only by carefully, continuously managing it was I able to finish up. Other than that one complaint, though, I was completely happy with my stay, and I would definitely stay here again.
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Public - a month ago
reviewed a month ago
The atmosphere is the main reason to go here: the standard evening entertainment is two gentlemen playing excellent authentic Greek music along with covers of Beatles songs and the like. It's impossibly joyous. The staff brought us a vase with our home country's flag stuck in it, as they do for everyone -- and when they found out we were there on our honeymoon, they really went into overdrive. They brought us a guest book to sign and took our picture to paste into it, and the singers serenaded us with a cover of the Beatles hit "When I'm 64." We loved it. But don't let my focus on the atmosphere and entertainment make you think I didn't notice the yummy food -- it was very good as well. But honestly, I'd enthusiastically return for the music and the company even if the food had been awful. What a terrific place; even the memory of it makes me happy. Plus, cats! What's not to like?!
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Public - 2 months ago
reviewed 2 months ago
Gorgeous, swanky place with great views and excellent customer service.
Public - 4 months ago
reviewed 4 months ago