1862

And this is why Enceladus is my favourite thing in the solar system.

1863

Elon Musk will be giving his Mars presentation shortly

Live stream and VOD here:

1864

All the other intelligent civs are cetaceans and birds. It takes a long time to build a radio telescope with flippers and beaks lol.

1865

Havenā€™t watched the Q&A section, but did they say anything about the radiation problem?

1866

I donā€™t think Iā€™ve ever watched Elon Musk give a speech. I assumed he would be a slick businessman with a well rehearsed speech, but instead he appears to just be winging it!

1867

Nope, that his normal speaking and presentation style. Sometimes when he does a product role like the Model III rollout he is more polished. But he is an engineer not a marketing guy like Jobs.

Of course, Jobs couldnā€™t explain the physics of everything.

1868

A Verge reporter asked the question about radiation and keeping people self.

He said there will be a small amount of shielding and the engine will face the sun. But overall while radiation will probably result in modest increase in cancer it is a pretty small risk. Lots of people bring it up but it, but the risk is exaggerated.

My thoughts are that for the first million people, your chances of dying of Mars environmental risk are easily and order of magnitude higher than cancer risk.

1869

Tardigrade DNA inserted into human cells gives them X-ray resistance
By Jessica Hall on September 23, 2016 at 1:00 pm 32 Comments

A study just broke out of Tokyo that says some eyebrow-raising things about water bears and their DNA. First among the revelations is the finding that water bears might not be all that much not-tardigrade at all. Remember that story about the tardigrade genome being about 17% foreign DNA? The Tokyo University team suspected that might have been because of contamination. So, for their own experiments, they took some extra precautions when getting ready to make their little vials of extract of tardigrade. And by precautions, I mean dosing the water bears with antibiotics and soaking them in bleach. Itā€™s like how a surgeon scrubs before surgery; any microbe that can hang on through that chemical and physical onslaught probably belongs there, so itā€™s easier to mind their potential for contamination because we know to look for it.

The particular kind of water bear the researchers chose to work with is also germane. The prior art used a relatively squishy species of freshwaterbear (is that a word? Itā€™s a word now) called Hypsibius dujardini, whereas the Tokyo study decided to use the hardier Ramazzottius varieornatus precisely because itā€™s so tough to kill, and they wanted to find out why.

When the results of the sequencing came back, the Tokyo researchers found that the tardigrade genome was composed of more like 1.2% foreign DNA, which is a far cry from a sixth of the thingā€™s genes coming from lateral gene transfer. In their paper, they politely refer to the previous, possibly adulterated results as a ā€œdraft genome.ā€

What they did find in the cleaner, less fragmented genome was a series of proteins, which protect the water bearsā€™ DNA from damage. Some manage the organismā€™s response to oxidative stress or dehydration. They have four copies of a gene coding for proteins good at repairing DNA double-strand breaks, like those resulting from physical damage, such as decompression, dehydration, or freezing. And thereā€™s one notable protein thatā€™s specific to water bears, capable of repairing DNA damage from high doses of radiation.

The Tokyo University researchers were even able to watch the protein go about its work by tagging parts of the tardigrade genome with green fluorescent protein (GFP) and then watching as the protein migrated through cells in culture. The damage-suppressing protein, Dsup, is closely associated with nuclear DNA; the scientists found it in the chromatin fragment of their cream-of-tardigrade soup. Chromatin is sort of like the options page of the DNA molecule, in that it determines which parts of the DNA molecule are transcribed.

a) Free-swimming waterbear; b) Waterbear in its dehydrated ā€˜tunā€™ state; c) contents of the updated R. varieornatus genome. Image: Kyoto et al, via Nature Communications
a) Free-swimming waterbear; b) Waterbear in its dehydrated ā€˜tunā€™ state; c) contents of the updated R. varieornatus genome. Image: Kunieda et al, via Nature Communications
This is where it gets a little weird.

When the team treated human cells in culture with extract of tardigrade, the GFP-tagged proteins stuck to human DNA just like they stick to tardigrade DNA, and cheerfully started doing what they do best: tamping down oxidative stress. When X-rays hit human cells, they do two kinds of damage. X-rays can cause direct DNA strand breaks, which are mostly single-strand. When they strike water molecules, they can also excite them into producing reactive oxygen species, which also cause single-strand breaks. High enough doses of X-rays can cause double-strand breaks. The damage-suppressing protein Dsup went immediately to work on the culture of human cells, suppressing or repairing single-strand and double-strand breaks by about 40%.

Clearly this means we can consume water bears to gain their powers. The study authors remark that the gene portfolio of the tardigrade represents ā€œa treasury of genesā€ to improve or augment stress tolerance in other cells. Plug-and-play genetics, anyone?

Also: in the course of researching this story, I discovered that in 2008 there was an ESA-sponsored tardigrade science project called TARDIS: TARDigrades In Space. The ESA also did an experiment where they stuck Martian rocks into the heatshield of a spacecraft and found out that re-entry ablated away the top two-thirds of the dolomite, implying that nothing shallower than an inch deep in the rock could possibly survive the trip. Obviously this doesnā€™t make hard conclusions about the idea of panspermia, but it does require us to examine our assumptions about how life on our planet might have begun.

1870

If you can do it in Kerbal, Elon can do it in real life.

1871

Love it!

1872

1873

The Q&A was terrible. Full of complete non-questions mostly using the air-time to market their products.

One question was close to mine (about the Mars cycler), however. I would have asked about why they chose that particular ship design. e.g. why not use a more modular one so that only parts of it land, and if required return, rather than the entire thing going down and the entire thing coming back from Mars surface?

And what are their thoughts about water as a propellant?

1874

Yeah, I just tried to watch the Q&A tonight and turned it off halfway through the guy asking the SECOND QUESTION. Holy crap, who let these assholes in there? Epic moment in history and people are talking about poop at burning man and marketing their books and shit. Why does humanity suck so much?

1875

Ya, I agree. I would have thought my caveat that 1/2 the population has an IQ under 100,might not have applied at a space conference.`

I thought he talked about water as propellant and why it was inferior but donā€™t remember the answer.

To me the disadvantage of modular design is re-usabliity. Letā€™s say you leave a fuel tank and engines on Mars. You then have to add them back on at earth. I read Buzz Aldrins book about going to Mars, and while there is a lot of scientific elegance to his theory (at least I think, it is clear that Buzz is approaching the problem as a scientific one how can I get the most payload to more with lowest amount of thrust/weight. Whereas Elon is looking at as business problem, what is most economical way of getting a one million people to Mars.

Here are some encouraging calculations. I spent most of my career at Intel, so I looked at most any engineering problem from the perspective of Mooreā€™s law. Since 1969, the number of transistors on Intel chips has increased at the rate of 48% compounded per year. Or almost exactly what the revised Moores law say the number of transistors doubled every two years. Costs have followed almost exactly. The growth rate has been slowing recently but was higher in the beginning.

Musk needs a $10/billion to $200K cost reduction or 50,0000 times to get his making Mars affordable. If Musk can drive down space costs as Intel and the semiconductor industry did chips prices, he can achieve this in 26-27 years,.
It is hard to get great numbers on launch cost, but it does look like weā€™ve seen at least an order of magnitude drop in cost per KG to LEO since SpaceX enter the market which would put them at Mooreā€™s law speeds.

1876

Remember that SpaceX rocket that exploded recently on the launchpad?

The investigation is getting weird

1877

Oh, come on. At this point I think whoever suggested they shouldnā€™t be investigating their own failures is on to something.

Maybe it was corporate sabotage, or maybe theyā€™re grasping at straws.

1878

I like that they had to appeal to the public for their crappy quality videos. it implies they spend billions developing the rocket, but only spend 500 on a single camera recording it taking off. Iā€™d have thought in this day and age there would be cameras on every surface possible.

1879

Still canā€™t rule out a Dyson Swarm!

1880

Blue Origin has a livestream of their inflight escape test in four minutes. First inflight escape test since Little Joe II in 1966.

1881

Aaand after a 10-minute hold, the countdown restarts at 15 minutes.