And the link to the Part II, Strategic Finance: https://rein.pk/startup-finance-for-founders-part-ii-strateg...

This is where a short abstract or executive summary upfront can make all the difference. If the main points are summarized, they will (hopefully) be read; the rest of the document, no matter the format, can then be read for context or with references from summary.

Having read this today, went home and watched https://skidrowmarathon.com/ tonight. Each of these are a way of showing the power of giving people dignity.

O well - better luck next time. Hopefully they got some more good data...would rather they have this issue now than when landing Red Dragon on Mars..!!

It's awesome that this is just an "oh well" rather than the huge disaster it would have been with any past reusable system. It would be better if it had worked, but I love how they've set it up so that their program can tolerate failures like this.

No telemetry from the landing stage? Or views from the nearby boats (how close is the nearest boat anyway?)

Well, they (the people at spacex) probably have everything, but I don't have access to this information :) Just watching the webcast, nothing indicated if the landing was ok or not. The people presenting the cast didn't know either.

They have just said that they got lots of good data. Even though the landing failed.

The boats are quite a distance away. During the JCSAT-14 mission, there was actually video on the webcast from one of the boats, and the barge was over the horizon. It was night, so it's hard to get a feel for just how far away, though.

Did the "experimental landing" work this time?

No clear word yet. Feed froze as usual and whatever was on the screen was covered in black smoke.

I did see something upright though, so who knows.

Meanwhile, for anyone looking for one of the most epic moments: https://youtu.be/L0bMeDj76ig?t=29m28s

No. It appeared briefly on the deck, but Elon tweeted it was a RUD, and that they'll be releasing video once they get access to it later today.

I love the commentator's wording: "We'll see whether yes, we landed, or no, we've got more experimental data."

Feed died.

I hope the next-gen of communications satellites improves the broadband-over-satellite situation.

If only there was a company in this day and age that is launching satellites often and at lower cost. :)

Apparently the broadband out there is great. The issue isn't lack of satellites or speed.

The issue is that when you have a Merlin 1D (or 3) firing directly at a mobile platform, it's going to shake violently. And when you have sensitive equipment on that platform shaking, you're going to have a satellite misalignment and signal cut outs while the lock is reacquired.

Considering this is a pretty unique scenario (I would imagine 99% of satellite internet connections don't have rockets landing on them), I doubt it's a high priority to resolve somehow.

On the telecast they just said it appears the vehicle was lost.

Seems like one engine was low on thrust:

https://twitter.com/elonmusk/status/743097337782763521

It's not clear. The video feed cut off at landing. There was a lot of smoke, and possibly a standing rocket.

...and now there is an interesting image showing the signals from the twin LIGO detectors - fantastic!!

Is this paper mirrored anywhere else yet? The Phys. Rev. Letters site appears to be a bit overloaded!

Here's the abstract:

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10−21. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410+160−180  Mpc corresponding to a redshift z=0.09+0.03−0.04. In the source frame, the initial black hole masses are 36+5−4M⊙ and 29+4−4M⊙, and the final black hole mass is 62+4−4M⊙, with 3.0+0.5−0.5M⊙c2 radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

I dabbled with GR many years ago, so I'd have been surprised if this hadn't turned up sooner or later... but My God, look at that... three earth masses-worth of radiated gravitational energy, I can hardly fathom that.

I think that's three solar masses.

My bad, you're right — my astonishment has risen by orders of magnitude.

Intermediate mass black holes are 100 to 1 million solar masses.

I understand frequency, SNR and significance. The other numbers are mysterious to me; anyone who understands the entirety of this abstract care to explain what the other numbers mean?

Possibly simpler than it looks.

410Mpc = 410 megaparsecs, which is about 1.3 billion light years

62M⊙ = 62 x the mass of the sun

The values have 90% error bars:

62+4−4M⊙ = 62 +/-4 solar masses

As the comments below say, the abstract says that three whole solar masses were converted to gravity waves when the black holes merged.

I'm not sure what the state of research into black hole mergers is, but the science that explains that number is going to be really interesting.

Thanks...but it was the rest of the paper itself I was wanting to look at! Trying to download the pdf...along with a fair few other from the slowness of the site.

Just to add a sense of scale, the co-moving distance to that back hole merge is roughly 1/60th the diameter of the observable universe!

Simultaneously? Are we sure?

(Joking, kind of...)

That's some serious history of physics nerd funny - it's reference to a very embarrassing failure to include time zone discrepancies when analyzing some of the first gravity wave data back in the 1960's

Woohoo, thank you!

Thank you!

Currently a "Placeholder APOD" until the LIGO Press Conference at 11AM (ET)...we're waiting!!