Disqus - Latest Comments for shawndgoldman

Re: TBT: Check out my new pad.

Shawn Domagal-Goldman — Fri, 14 Nov 2014 17:16:23 -0000

YES. But first I need a spacecraft. So I guess we have to to Orange County CHopper first:
http://en.wikipedia.org/wik...

Re: TBT: Check out my new pad.

Shawn Domagal-Goldman — Fri, 14 Nov 2014 17:11:30 -0000

Hooray for Disqus reactivation!

Re: #TBT #Astrobiology a new look at an old meme

Shawn Domagal-Goldman — Fri, 17 Oct 2014 15:31:44 -0000

Ha! Well there is a bit of psueo-analysis implied, right? What we really do is very similar to what other scientists do... which is a lot of coding and field work and column chemistry and gene amplification, etc. (Although we're probably only doing one or two of these per person.) But people outside the field think something totally different about our daily activities.

Re: Why Is NASA's Astrobiology Program Ignoring \"Cosmos\"?

Shawn Domagal-Goldman — Mon, 17 Mar 2014 22:53:38 -0000

Well - and now I'm *REALLY* exhibiting my biases - I think one thing the NAI has done particularly well is develop astrobiology as an area of focused research, and an associated professional community to pursue it.

As a result of those efforts, we have a generation of astrobiologists (including yours truly) with degrees or certificates in the field and multi-discipline research networks tailored to the search for life beyond Earth. They're now working alongside senior scientists whose research has significantly advanced our understanding of the possibilities for life and the interactions of our biosphere with the rest of the planet. Developing that science community had to come first, and I think the NAI was successful in that endeavor.

So how should we leverage this to take astrobiology to the next level? It's a great question, but it's also a great time to be asking it. With the re-organization of PSD's R&A program (an opportunity for expanding the astrobiology community), a new head of the NAI, and new NAI teams about to be selected, there's lots of change afoot. But with that change comes opportunity.

Re: Why Is NASA's Astrobiology Program Ignoring \"Cosmos\"?

Shawn Domagal-Goldman — Mon, 17 Mar 2014 21:18:17 -0000

As to the Astrobiology Program and the NAI, I think you have a point that this is an opportunity to be leveraged.

However, it's not such an obvious choice for a research program to do this. Tweeting is free, but tweeting effectively is far from it. To really do it right you want to have a team, ala the Curiosity Rover twitter team, with scientists, public engagement experts, and social media experts. That ain't cheap, and it would siphon money away from grants for research. And it's not like you can just "rent" an effective social media team for events like this.

Further, although astrobiology is the backbone of the material covered on Cosmos, there's lots of planetary science, Earth science, heliophysics, and astrophysics presented as well. To that end, it shows how astrobiology provides a nice theme for the scientific endeavors of the agency, but the science presented transcends astrobiology. So maybe SMD should be doing this, with input from all the divisions (including a lot of material from AB)?

Honestly, I don't have the answer here. But that's why I don't think it's an easy call, especially when research funding is tight. (Should *every* large research program at NASA have a social media team?) It's also why I was really happy to see the accounts with an existing standing team (@NASA, @NASAGoddard, @NASA_EO, etc) tweeting. To me, that makes a LOT more sense than standing up a team just for this opportunity.

(Full disclosure: I'm a CS at GSFC, and my last postdoc was in the Astrobiology Program at HQ. So I have a bias towards trusting these folks, who I know value outreach and whom I have personally seen make good decisions in a budget-limited environment. Also, the thoughts above are all my own, not representative of any of them.)

Re: Why Is NASA's Astrobiology Program Ignoring \"Cosmos\"?

Shawn Domagal-Goldman — Mon, 17 Mar 2014 21:06:54 -0000

Hey, thanks! I appreciate the shout-out.

Re: Why Is NASA's Astrobiology Program Ignoring \"Cosmos\"?

Shawn Domagal-Goldman — Sun, 16 Mar 2014 23:07:24 -0000

If anyone would like an astrobiology perspective (but certainly not THE astrobiology perspective) on this, I've been tweeting about the show (@shawndgoldman) - at times from an astrobiological perspective - and recording my thoughts at http://paleblueblog.org.

I don't have any advance notice of what the content is, so all the posts are off-the-cuff (and, naturally, < 140 characters). And, just like the rest of you, I spend a lot of time in total awe of the amazing graphics package. But I have some insights into the research that's the foundation of the series, and I try to bring in the thoughts of other planetary scientists and astrobiologists when I catch their tweets.

Re: Survey says….

Shawn Domagal-Goldman — Sat, 23 Nov 2013 16:43:46 -0000

Right! For most astrobiological endeavors, we generally do not discriminate. We'd be happy with any form of life, "intelligent" or otherwise.

Re: Survey says….

Shawn Domagal-Goldman — Sat, 23 Nov 2013 16:42:41 -0000

I think the number of eta-Earth is certainly still debatable, but I think it should be higher than 1%, even if you're fairly conservative in where you draw your boundaries. I think the range in uncertainty is more like 5% on the low side and 50% on the high side. All those are in the billions to tens of billions of potentially habitable worlds out there.

As to how many have life? Or intelligent civilizations? Or, for that matter, to measure and confirm habitability and the presence of oceans? That's what we need the next telescope for. :-)

Re: Survey says….

Shawn Domagal-Goldman — Sun, 10 Nov 2013 20:18:33 -0000

I hear ya! The good news is even in a case where we don't get everything we want, we still might get what we need. Or, at least that's my hope. :-)

Re: Survey says….

Shawn Domagal-Goldman — Sun, 10 Nov 2013 18:25:28 -0000

You may be right about the "low side" thing. Personally, I think it depends on how you're counting. I think the number for "Sun-like" stars will end up around 0.1 (10%). I think for all stars it may approach 0.5 (50%), which is astounding. We'll get a little more info when TESS and WFIRST fly - TESS will attack planets inside the inner edge of the habitable zone quite well... and WFIRST will do the same outside the outer edge.

I also think your other points right on the mark.

Ad astra... and ad planetae? ;-)

Re: Habitable Zone Lifetimes of Exoplanets around Main Sequence Stars

Shawn Domagal-Goldman — Wed, 25 Sep 2013 04:03:07 -0000

Approved

Re: More on the prospects for life on KOI-172.02

Shawn Domagal-Goldman — Tue, 29 Jan 2013 23:50:26 -0000

Randy,

Your math is correct! If the planet has the same albedo and same greenhouse effect as Earth it would have a surface temperature around 320 K (47 C/116 F). That's sounds pretty hot to you and me, but it's not uninhabitable. And as you point out, many microbes are quite happy in such temperatures. Heck, my folks have been through a few days that hot in the sun of Arizona. Some researchers (not me) even think Earth's average temperature was that high for much of its history.

However, there's an inherent assumption there - that the planet has the same greenhouse effect the Earth does. But if KOI-172.02 has an albedo of 0.3, it will absorb a LOT more energy than Earth does. And if that happens, it will have a lot more water vapor in the atmosphere, in turn leading to a higher greenhouse effect and a higher surface temperature. This probably still wouldn't "kill" the planet, but it would make it warmer than 320K.

What's worse, with that much water in the atmosphere, lots of it would get up into the upper atmosphere where it can be blown up by radiation and have its hydrogen atoms escape to space. That would lead to loss of the oceans -- and a planet that is uninhabitable, at least in the classic sense of the word.

You're also correct that if the albedo of the planet is higher, the planet could be habitable. That's the idea behind it having a haze layer similar to Titan or tremendously high amounts of cloud cover (something like 90% or more). That kind of planet could keep its oceans.

Re: More on the prospects for life on KOI-172.02

Shawn Domagal-Goldman — Sat, 12 Jan 2013 21:00:23 -0000

I do have one quibble with the Kepler team's habitability metrics, specifically the use of equilibrium temperature to estimate habitability. The equilibrium temperatures published by the Kepler team assume an "Earth-like" reflectivity. But in order to be habitable, KOI-172.02 planet must have a reflectivity higher than Earth. So, the planet is either outside the habitable zone, contrary to the team's claims... OR the planet has an equilibrium temperature that is different from the value published by the team. The team has put themselves in a scenario where they can't be right in both respects.

Re: KOI-172.02: An excellent candidate for a “Venus-twin”

Shawn Domagal-Goldman — Fri, 11 Jan 2013 21:35:06 -0000

I should also point out that this planet, if/when it is confirmed, DOES qualify as "the most Earth-like planet known around a Sun-type star." That's still a very, very, very cool discovery. But it's not the "jackpot/Earth-twin" that it's being widely reported as in the media.

In other words, even though I'm complaining that this isn't an Earth-twin, it's still probably *more* similar to Earth than the other planets we know of that orbit Sun-like stars.

Re: KOI-172.02: An excellent candidate for a “Venus-twin”

Shawn Domagal-Goldman — Fri, 11 Jan 2013 21:32:52 -0000

The simplest form of the calculation is this: the amount of energy (F) the planet receives is proportional to the 4th power of the star's temperature (T), the 2nd power of the star's radius (Rs), and inversely proportional to the 2nd power of the orbiting distance (a). In equation form (normalizing everything to the Earth-Sun system):

F = (T^4)*(Rs^2)/(a^2)

According to the Kepler database, for KOI-172.02 the star's temperature of 1.008 times that of the Sun, but the star is dimmer than the Sun because it is only 0.9 times the Sun's radius. The planet has an orbiting distance 0.762 times that of the Earth. Putting all that together,

F(172.02) = (1.008^4)*(0.9^2)/(0.762^2) = 1.44

So KOI-172.02 gets about 44% more energy than the Earth gets. According to the papers on this (see Kasting et al., 1997 or Selsis et al., 2007), that's enough to cause the planet's water to get into the upper atmosphere, where it can get blown up by radiation and the H atoms then escape to space. It's also probably enough to also trigger a runaway greenhouse.

Now... the caveats I posted above still apply. This planet could be habitable if any of these measurements are "off" and their actual values move things towards lower energy. Or it could be that KOI-172.02 has enough cloud cover to block lots of the incoming radiation from the star. Or we could just be wrong on whether or not a Venus planet could support life. But all those involve us being "wrong" in some way. If KOI-172.02 has life, that means either the properties in the database are wrong, or our habitable zone boundaries are wrong, or our understanding of the limits of life are wrong.

Re: KOI-172.02: An excellent candidate for a “Venus-twin”

Shawn Domagal-Goldman — Fri, 11 Jan 2013 15:31:08 -0000

Sorry, I didn't mean to be short/dismissive, I just don't have time to elaborate until later.

You and Alan have a very legitimate concern, which is reflective of the reporting on this. I'm not at AAS this year, so I can't speak to what NASA personnel are/aren't saying on it. But I'm fairly confident in my analysis. More later...

Re: KOI-172.02: An excellent candidate for a “Venus-twin”

Shawn Domagal-Goldman — Fri, 11 Jan 2013 13:34:39 -0000

Matt/Alan, I have done that research. Even if you account for that you get too much energy. I'll post the math here after work is done.

Re: KOI-172.02: An excellent candidate for a “Venus-twin”

Shawn Domagal-Goldman — Fri, 11 Jan 2013 07:50:06 -0000

If you have questions about all this, leave them here. But I won't be able to answer them during the work-day today, as I have a retreat with all-day meetings. I'll try to answer any questions when I get home.

Re: No Methane on Mars – at least not now in Gale Crater…

Shawn Domagal-Goldman — Fri, 02 Nov 2012 17:40:22 -0000

Take a look now - it's fixed. Apologies for the confusion.

Re: No Methane on Mars – at least not now in Gale Crater…

Shawn Domagal-Goldman — Fri, 02 Nov 2012 17:01:05 -0000

Thanks! But I just realized I screwed something up in the article. Curiosity is just South of the equator... which means the fact that it is late Winter there also implies it is late Summer in the Northern Hemisphere. I'm going to correct this momentarily...

Re: Sunday Riddle!

Shawn Domagal-Goldman — Mon, 01 Oct 2012 09:50:54 -0000

Hmmm... back-and? ampersand? Reverse-and? My coffee isn't working.

Re: Imagine Harder

Shawn Domagal-Goldman — Tue, 07 Aug 2012 12:53:18 -0000

Indeed! This is one of the reasons that committees such as those organized by the National Academy of Sciences and the IPCC are so critical.

Re: Imagine Harder

Shawn Domagal-Goldman — Tue, 07 Aug 2012 10:12:37 -0000

Excellent post, lev!

One of the challenges to space exploration is the need no get our monkey brains not just to "imagine harder" but to "imagine longer." Sometimes it seems that our attention spans are getting shorter and shorter, with instant gratification becoming ever more emphasized. Yet space exploration requires a long-term focus to maintain efforts whose benefits may not be realized for years or even decades.

Re: Curiosity has landed!

Shawn Domagal-Goldman — Mon, 06 Aug 2012 04:10:50 -0000

Yahoooooo!!!!