Posts by Mike Hewson

11) Message boards : Science : new analytic model for signal from colliding neutron stars (Message 141180)
Posted 5 days ago by Profile Mike Hewson
Here's the main claim ( my emphasis ) :
Our model is the first semi-analytical model which captures the tidal amplification effects close to merger. It thereby provides the most accurate analytical representation of binary neutron star dynamics and waveforms currently available.

which would emerge as signal templates for inspiral/merges cases. However we analyse continuous waves here ie. that for which the time evolution is very little or none.

Don't worry, I was here for four years before it was kindly pointed out to me that we don't do inspirals ! :-)

Cheers, Mike.
12) Message boards : Cafe Einstein : Seti Refuge Bar & Bistro Wing of Cafe Einstein (Message 141178)
Posted 5 days ago by Profile Mike Hewson
I'll put $20 on Scarlett. :-)

Cheers, Mike.
13) Message boards : Cafe Einstein : Seti Refuge Bar & Bistro Wing of Cafe Einstein (Message 141166)
Posted 6 days ago by Profile Mike Hewson

Awww :) Hope you've stocked up on knock knock jokes :D

I think I've a few somewhere.... :o)

People will say they grow up quick. And they do, just watch yourself. As a youngun' I discovered that I could squeeze a bag of crisps without the crisps going everywhere.

Many an unknowing adult had a young Sparky sneaking up behind them with a bag of crisps stifling the laughter and just waiting to pop the bag.

Hilarity, profanity and a grounding usually followed :)

Oh they do change! The care-giving adults get used to a child in Configuration H1 and then in a few weeks time they have moved on to Configuration Q2. Moving targets. Perfectly normal development. Alas no one really remembers their own early years ie. improving memory functionality is part of said development. Hence most adults will say they were a good child - they don't recall otherwise ! :-)

But it's a feedback thingy. So if early crisp-bag-popping skill even accidentally develops the response obtained determines the further evolution of that trick. Kids frequently play with ( manipulate ) their parents eg. dummy spitting, food refusal, oooh-I-accidentally-dropped-it-(again)-will-you-pick-it-up-(again), breath holding, sneaky poo ..... :-)

Cheers, Mike.
14) Message boards : Cafe Einstein : Seti Refuge Bar & Bistro Wing of Cafe Einstein (Message 141141)
Posted 7 days ago by Profile Mike Hewson
Just when I thought I was all grown up, this young lady brought me to my senses...

Gorgeous ! :-)

Yep, she'll knock out your pretensions of maturity for sure .... kids are great for keeping things real. :-) :-)

Cheers, Mike.
15) Message boards : Cafe Einstein : Seti Refuge Bar & Bistro Wing of Cafe Einstein (Message 141138)
Posted 7 days ago by Profile Mike Hewson
Yep, the bigger hairy one looks rather dopey. As for the pink one, her mother will not mind me mentioning that some successes are rather hard won indeed, with the reward as evident in the photo. :-) :-)

Cheers, Mike.
16) Message boards : Cafe Einstein : SpaceX Dragon scheduled for 12/19 (Message 141125)
Posted 8 days ago by Profile Mike Hewson
Mike, I was about to compose a post arguing that the Heavy was not so good a candidate for recovery, and that in any case I did not think they would delay first launch for the capability, when I did a little background checking to see if I could find something SpaceX had said about heavy recovery.

Imagine my surprise on finding this animation video from SpaceX showing Heavy recovery of three separate pieces--each piece considerably like the Falcon 9, and appearing to use the same recovery scheme, but landing not on a barge (or three!) but right back at the Cape.

youtube posting of SpaceX heavy launch and recovery animation

One of my arguments against is that the most obvious customers for the Falcon Heavy are rather primitively risk-adverse. My personal guess is that use on operational launches of the Heavy will probably come after a string of successes on less sensitive Falcon 9 launches.

If you think about the customers for Heavy launches, you may find an additional reason to discount Energia use. I don't think NRO would appreciate a fully Russian booster nearly so much as they do mere rocket engines with a strong Russian heritage--which have given them indigestion. Anyway, I think that Energia booster (confusingly the name applied both to an organization and to a particular booster) has nothing resembling a current manufacturing base. Might as well propose to start up building Saturn V's again.

For others with a bit of curiosity on this relic of the Soviet space shuttle program, here is a not bad overview article Energia overview

Agreed. There is considerable subtlety in the Musk/SpaceX approach which makes it both more interesting and more risky. I vaguely recall several years ago Elon's comments in generality - alas I've forgotten the detail or a reference to it - about the task of reaching orbit from this planet with the chemical fuels as actually available ( he's a very deep thinker ). The take home messages were :

- the margin is only of the order of 5% at the utmost best case ie. mildly greater surface gravity and/or mildly less fuel energy density and we'd fail to even reach low Earth orbit.

- you can only tweak/optimise a little. Even a 0.5% improvement is a marvellous gain. There is no 'killer app' that will arrive one day to solve that.

Hence Mars - at one third gee surface - would be a doddle to launch or return from. But for the same reason however it doesn't have an atmosphere that natively supports our oxidative metabolism. No where near it. And it is oxidation that gets you to orbit ie. the best performers include LOX. A lovely catch-22 there.

I interpreted that to mean : given that you need to achieve ~ 7 km/sec for each and every kilo to low Earth orbit and then another 4 km/sec to leave Earth's vicinity to travel around the solar system then ( short of the miraculous ) one has to construct large ventures in orbit first by very many up/down hops, and then go from there. Hence hardware re-usability.

The other aspect is design re-usability ie. don't keep inventing different wheels. Don't keep re-certifying radically new approaches. Thus 1 x Heavy = 3 x Falcon-9's. They have the same interstage and upper shroud/stage. A Falcon-9 has nine identical engines. A Dragon has three interior modes and thus roles. One type of leg strut for those bits that return. This is high-tech LEGO writ large.

Cheers, Mike.
17) Message boards : Cafe Einstein : SpaceX Dragon scheduled for 12/19 (Message 141108)
Posted 9 days ago by Profile Mike Hewson
Looking at one thing and another my guess is that the 1st Falcon Heavy flight - as yet not precisely scheduled, but allegedly this year - could well be contingent upon a successful return-to-land demonstration for the Falcon-9 first stage. Why? Well, the Heavy is ~ 3 x Falcon-9 and it's quite a lot of expensive hardware to throw away at once otherwise. Also it would also look a tad silly to do so.

Cheers, Mike.

( edit ) Also I have been researching as to why the Russian Energia is not being mentioned in lift capacity comparisons. It has a quoted thrust of ~ 30 megaNewtons, so still well above Falcon Heavy at 17-20 megaNewtons. In any case the Heavy burns for longer and the Energia only sort of achieved it's goals in 1 of 2 test launches.
18) Message boards : Cafe Einstein : Seti Refuge Bar & Bistro Wing of Cafe Einstein (Message 141101)
Posted 9 days ago by Profile Mike Hewson
Howdy Mike, the electrons are currently being put back into my mobile after a flat battery incident, I must've been leaking electrons all over the place. Such a mess.

They do that. As long as you have not been charged with any offences all will be well ...

As for me I'm just running with the usual crowd :

Cheers, Mike.

( edit ) NB There are two children in the photo. Can you guess which one has reached middle age ? :-) :-)
19) Message boards : Cafe Einstein : Seti Refuge Bar & Bistro Wing of Cafe Einstein (Message 141082)
Posted 10 days ago by Profile Mike Hewson
Welcome, oh frog-eyed green and slimy one :-)

Please take a seat on a water lily frond ....

.... have you brought thus any bags of energetic electrons ?

Failing that, any news from across the interstellar hydrogen alpha line ? :-)

Cheers, Mike.
20) Message boards : Cafe Einstein : Cafe Einstein: LPTP # X V (Message 141009)
Posted 16 days ago by Profile Mike Hewson
Hi all,

Just popping in to say hi. I've been offline for a bit. I'm in Georgia attending engine school and will be here until the end of May.



Cool. Learn well. Best foot forward and all that .... :-)

Cheers, Mike.

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This material is based upon work supported by the National Science Foundation (NSF) under Grants PHY-1104902, PHY-1104617 and PHY-1105572 and by the Max Planck Gesellschaft (MPG). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the investigators and do not necessarily reflect the views of the NSF or the MPG.

Copyright © 2015 Bruce Allen