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-   -   What "weed need" is a space mission! (https://www.mersenneforum.org/showthread.php?t=17609)

Uncwilly 2018-12-04 20:34

[QUOTE=chalsall;501591]SpaceX are about to launch. [URL="https://www.spacex.com/webcast"]Live streaming for anyone who cares[/URL]....[/QUOTE]

I watched the stream on my mobile while on the road (I was not the driver.)

kladner 2018-12-05 02:29

SpaceX really seems to have a winning strategy, and a pretty regular commercial launch schedule. Almost 3 tons of "stuff" into orbit, on a reusable vehicle ain't shabby, either.

Uncwilly 2018-12-05 02:46

[QUOTE=kladner;501704]SpaceX really seems to have a winning strategy, and a pretty regular commercial launch schedule. Almost 3 tons of "stuff" into orbit, on a reusable vehicle ain't shabby, either.[/QUOTE]Should have another launch on Wednesday (#20). The last one was the 3rd launch of the same booster. 2019 they plan to do a 24-48 turn around on a first stage.

kladner 2018-12-05 05:27

[QUOTE=Uncwilly;501706]Should have another launch on Wednesday (#20). The last one was the [U]3rd launch of the same booster[/U]. 2019 they plan to do a [U]24-48 turn around on a first stage[/U].[/QUOTE]
:shock:

axn 2018-12-05 05:42

[QUOTE=kladner;501721]:shock:[/QUOTE]

?

kladner 2018-12-05 13:57

[QUOTE=axn;501724]?[/QUOTE]
The two items emphasized show progress on multiple fronts. Upping the reuse numbers, with speedy turn-arounds bespeak a practiced, smooth running system.

chalsall 2018-12-05 16:41

[QUOTE=kladner;501744]The two items emphasized show progress on multiple fronts. Upping the reuse numbers, with speedy turn-arounds bespeak a practiced, smooth running system.[/QUOTE]

SpaceX are [URL="https://www.spacex.com/webcast"]about to do their thing again in about 90 minutes[/URL]....

chalsall 2018-12-05 18:30

[QUOTE=chalsall;501753]SpaceX are [URL="https://www.spacex.com/webcast"]about to do their thing again in about 90 minutes[/URL]....[/QUOTE]

And things didn't appear to go so well for the Stage 1 landing. Lot's of spinning, and suddenly SpaceX cut away from the landing attempt....

Uncwilly 2018-12-05 18:42

[QUOTE=chalsall;501761]And things didn't appear to go so well for the Stage 1 landing. Lot's of spinning, and suddenly SpaceX cut away from the landing attempt....[/QUOTE]
It was a water landing near the cape. The reentry burn puts its path off-shore (or to miss the barge). The landing burn stears it onto the pad. It looked to me that it fought the wind to get on course and then decide that the wind was too strong and that it would not be same, then bailed out to the water. Will be interesting to hear what happened.
Two more launches with real dates slated by the end of the year for Space-X. That will bring the total to 22. Currently Space-X is responsible for about 2/3rds of the USA's launches this year.


<edit>From Twitter
[QUOTE=Elon Musk]Grid fin hydraulic pump stalled, so Falcon landed just out to sea. Appears to be undamaged & is transmitting data. Recovery ship dispatched.[/QUOTE]</edit>

Uncwilly 2018-12-05 18:57

[QUOTE=Uncwilly;501009]A little spy has informed me that Space-X is preparing to catch a fairing on Wednesday.[/QUOTE]My spy was right, even though Everyday Astronaut was reporting no. It was Monday, not Wednesday. And it was a miss.

[QUOTE=Elon]Falcon fairing halves missed the net, but touched down softly in the water. Mr Steven is picking them up. Plan is to dry them out & launch again. Nothing wrong with a little swim.[/QUOTE]

And the [URL="https://twitter.com/i/status/1069657950464073728"]video[/URL] from Space-X of Mr. Steven heading out to sea does not do it justice. I have seen large ships and the first stage of a Falcon9 from reasonable distances. Mr. Steven is a WOW!

chalsall 2018-12-05 19:01

[QUOTE=Uncwilly;501762]It was a water landing near the cape.[/QUOTE]

Yeah. But beyond analysis it's not likely to be of much use for reuse.

Trivial to have redundancy of hydraulic pressure...

chalsall 2018-12-05 21:35

[QUOTE=chalsall;501764]Trivial to have redundancy of hydraulic pressure...[/QUOTE]

A little bit dizzying to [URL="https://twitter.com/elonmusk"]watch[/URL].

The very expensive titanium grid fins are locked in position, while the rocket comes in for a soft landing on the ocean. Then it tips over....

Uncwilly 2018-12-05 22:02

Watch this view of the landing. [url]https://clips.twitch.tv/CleverSpineyEggPrimeMe[/url]

chalsall 2018-12-05 22:10

[QUOTE=Uncwilly;501776]Watch this view of the landing. [url]https://clips.twitch.tv/CleverSpineyEggPrimeMe[/url][/QUOTE]

Poor little thing. It tried really hard...

I'm sure lots of data will be analysed deeply by SpaceX. That's what they do, after all.

Failure is where you learn what not to do again....

fivemack 2018-12-06 16:05

[QUOTE=chalsall;501773]A little bit dizzying to [URL="https://twitter.com/elonmusk"]watch[/URL].

The very expensive titanium grid fins are locked in position, while the rocket comes in for a soft landing on the ocean. Then it tips over....[/QUOTE]

After a soft landing they can presumably remove, wash and reuse the very expensive titanium grid fins; it might be prohibitively expensive to requalify the engines themselves.

(in a similar direction, I believe SpaceX owns no more than two sets of space station docking adaptors, and just unscrews them from landed Dragons, test, and reinstall one onto the Dragon next in line to go to ISS)

ewmayer 2018-12-21 04:22

1 Attachment(s)
Saw the bluish-white lasso-shaped contrail pictured below on my way out of the 2nd-floor garage of the Novato (Marin county) Whole Foods - It was from a Vandenberg rocket launch, a heavy Delta IV carrying a spy satellite: [url]https://www.space.com/32286-space-calendar.html[/url]

ewmayer 2018-12-25 22:23

Re. my above post, things turned out to be much more interesting than that - a bunch of folks posted to the NextDoor site for my area, upshot is that the nearly-identical time Vandenberg launch I linked to was scrubbed, and that in fact the contrail was left by a very bright meteor which entered the atmosphere above us. I had a hard time believing it at first since no one confirmed actually seeing the flash of the bolide (and after all, disinformation is the spooks' stock in trade, though admittedly it would be odd to publicize the launch time in advance and then spread a fake cover story afterward), but over dinner last night the brother-in-law (who lives 10mi away) said they had seen the thing streaking downward while out driving. Damn, I must've *just* missed seeing that, never seen one so bright in my lifetime, at least not 'live'.

Uncwilly 2018-12-29 09:30

Hopefully all of the news media cover New Horizons encounter with Ultima Thule (closest approach is right around the change from 2018 to 2019 in the Eastern time zone) as well as they did for Pluto.

Also, NROL 71 may actually shuffle of the surface on Saturday.

xilman 2019-01-01 17:42

[QUOTE=Uncwilly;504260]Hopefully all of the news media cover New Horizons encounter with Ultima Thule (closest approach is right around the change from 2018 to 2019 in the Eastern time zone) as well as they did for Pluto.

Also, NROL 71 may actually shuffle of the surface on Saturday.[/QUOTE]

[URL="https://www.bbc.co.uk/news/science-environment-46729898"]It got there intact and has phoned home[/URL]. If Ultima Thule has an atmosphere or a dust cloud it was too thin to cause damage.

Nice picture, BTW. resolution not quite good enough to distinguish between a contact binary or a co-orbiting pair.

Spherical Cow 2019-01-01 17:56

[QUOTE=xilman;504602][URL="https://www.bbc.co.uk/news/science-environment-46729898"]It got there intact and has phoned home[/URL]. If Ultima Thule has an atmosphere or a dust cloud it was too thin to cause damage.

Nice picture, BTW. resolution not quite good enough to distinguish between a contact binary or a co-orbiting pair.[/QUOTE]

Outstanding- 6.5 billion km, and it skims past an object a few tens of km wide, and reports back using a 15 watt transmitter. Just incredible.

Uncwilly 2019-01-01 18:05

1 Attachment(s)
[QUOTE=xilman;504602]Nice picture, BTW. resolution not quite good enough to distinguish between a contact binary or a co-orbiting pair.[/QUOTE]
The images that they released were from significantly early. I took a single raw image and did some ham fisted processing to get this.

Brownfox 2019-01-01 20:12

Yop. Better images should be available tomorrow and then better still in the coming months. Current best guess seems to be a single elongated structure (think bowling pin) rather than a co-orbiting pair.

Dr Sardonicus 2019-01-01 20:50

[QUOTE=Spherical Cow;504603]Outstanding- 6.5 billion km, and it skims past an object a few tens of km wide, and reports back using a 15 watt transmitter. Just incredible.[/QUOTE]
Just [i]how[/i] incredible? The following was when NH was flying by Pluto. The quoted passage is about the challenges at the receiving end. When the Voyager probes were flying by Saturn, a guy from JPL described one major problem as being that "the receiver is not at absolute zero."

[url=https://www.quora.com/How-strong-is-the-signal-transmission-system-on-New-Horizons-that-its-able-to-send-data-back-to-earth-3-billion-miles-away]How strong is the signal transmission system on New Horizons that it's able to send data back to earth 3 billion miles away?[/url][quote]These dishes produce a signal about 29 million times stronger than the smallest possible antenna on that frequency band but it is still incredibly weak: about a millionth of a millionth of a millionth of a watt.

This is so weak that it would be completely lost in the receiver's own noise, so special amplifiers mounted right in the dish and cooled by liquid helium are used to boost the signal while adding as little noise as possible. Other sources of noise include water vapor in the atmosphere and even the distant cosmos behind the spacecraft, but little can be done about them.

Yet the signal is still so noisy that it would be lost if not for a final trick: error correction coding. New Horizons generates and adds 5 "parity" bits for each data bit so that when noise corrupts some of them they can be detected and corrected.[/quote]

chalsall 2019-01-02 02:33

[QUOTE=Dr Sardonicus;504620]The quoted passage is about the challenges at the receiving end. When the Voyager probes were flying by Saturn, a guy from JPL described one major problem as being that "the receiver is not at absolute zero.[/QUOTE]

What most people don't appreciate is the receiver has much more difficulty than the transmitter in getting a message through.

Please see [URL="https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem"]this Wikipedia article -- Shannon-Hartley theorem[/URL].

Interestingly, this forum has a much better Signal-to-Noise Ratio (SNR) than most of the entire Internet.... :smile:

Uncwilly 2019-01-02 04:50

1 Attachment(s)
In the book about NH Alan Stern talked about how that the low bit rate was an intentional choice to make the mission possible. The power limitation of a single RTG was one factor. Size/mass/complexity of the antenna was another factor.

I grabbed the latest and best image and processed it again. Looks like the larger lobe has a lump on the side.

axn 2019-01-02 06:03

[QUOTE=Uncwilly;504649]I grabbed the latest and best image and processed it again. Looks like the larger lobe has a lump on the side.[/QUOTE]

Now it looks like a fetus. Pareidolia FTW!

Dr Sardonicus 2019-01-02 13:53

[QUOTE=Uncwilly;504649]I grabbed the latest and best image and processed it again. Looks like the larger lobe has a lump on the side.[/QUOTE]Remember the "Dawn of Man" scene from [i]2001: A Space Odyssey[/i]? It's the bone!

xilman 2019-01-02 18:45

[QUOTE=Dr Sardonicus;504658]Remember the "Dawn of Man" scene from [i]2001: A Space Odyssey[/i]? It's the bone![/QUOTE]Nah, it can't be. It came back down and killed the pre-human. Remember Gilliam's Monty Python cartoon?

Dr Sardonicus 2019-01-03 01:08

[QUOTE=xilman;504683]Nah, it can't be. It came back down and killed the pre-human. Remember Gilliam's Monty Python cartoon?[/QUOTE]No. And it couldn't have. It nearly hit a space ship in modern times. Don't you remember the [b]MAD[/b] Magazine movie satire?

[u]Update:[/u] New images are now all over the Internet. It's a "contact binary." Sort of like an unfinished snowman.

xilman 2019-01-12 17:17

Beautiful pictures from [URL="https://www.bbc.co.uk/news/science-environment-46836047"]the dark side of the moon[/URL].[SUP]*[/SUP]

* There's no dark side of the moon really. As a matter of fact, it's all dark. The albedo is around 0.12, comparable with that of worn asphalt.

kladner 2019-01-13 17:17

[QUOTE]The rover and lander are carrying instruments to analyse the region's [U][B]geology[/B][/U].[/QUOTE]Shouldn't this be "selenology"? :razz:

xilman 2019-01-13 17:42

[QUOTE=kladner;505775]Shouldn't this be "selenology"? :razz:[/QUOTE]Yup

ewmayer 2019-01-14 20:25

[url=https://wolfstreet.com/2019/01/11/oops-after-funding-fiasco-in-november-spacex-to-lay-off-10-of-its-employees/]Oops, SpaceX to Lay Off 10% of its Employees after Funding Fiasco in November[/url] | Wolf Street

Batalov 2019-01-14 23:38

[QUOTE=xilman;505711]* There's no dark side of the moon really. As a matter of fact, it's all dark [/QUOTE]
"...the only thing that makes it[I] look[/I] light is the Sun."
[YOUTUBE]fGS9auPPDsg[/YOUTUBE]

[SPOILER]Another fun fact is that one of the roadies (who also provided voice bits) was Naomi Watts' father [/SPOILER]

chalsall 2019-02-13 19:02

NASA is saying goodbye to Opportunity...
 
For extreme geeks, this might be of interest.

Sadly, NASA has tried its best, but the Opportunity Rover has been declared dead. [URL="https://www.youtube.com/watch?v=21X5lGlDOfg"]NASA TV[/URL].

May it rest in peace, after doing much more than expected....

retina 2019-02-13 19:14

[QUOTE=chalsall;508449]For extreme geeks, this might be of interest.

Sadly, NASA has tried its best, but the Opportunity Rover has been declared dead. [URL="https://www.youtube.com/watch?v=21X5lGlDOfg"]NASA TV[/URL].

May it rest in peace, after doing much more than expected....[/QUOTE]Yeah. Farewell Opportunity. Thanks for your efforts.

[url]https://xkcd.com/2111/[/url]

chalsall 2019-02-13 19:49

[QUOTE=retina;508450]Yeah. Farewell Opportunity. Thanks for your efforts.[/QUOTE]

Indeed. The live stream is really quite emotional.

There was a very touching bit delivered by Jennifer talking about a serious software issue.

[URL="https://www.rapitasystems.com/blog/what-really-happened-to-the-software-on-the-mars-pathfinder-spacecraft"]Priority Inversion[/URL], for those interested....

Dr Sardonicus 2019-02-14 01:04

The life of the Opportunity probe had been estimated at 90 days. Due to the aforementioned computer problem, it very nearly didn't make it that long.

It wound up lasting, and being productive, 60 [i]times[/i] as long as its estimated lifetime.

Well done, and farewell.

chalsall 2019-02-14 01:31

[QUOTE=Dr Sardonicus;508510]Well done, and farewell.[/QUOTE]

I actually cried during that broadcast.

I'm pathetic. I'm OK with that.

retina 2019-02-14 21:38

I will be the most sad when Voyager 1 & 2 stop communicating. They are the most successful probes IMO.

41 years and still going. :bow:

nomead 2019-02-15 00:54

[URL="https://en.wikipedia.org/wiki/AMSAT-OSCAR_7"]AMSAT-OSCAR 7[/URL]
While not actually an interplanetary probe, it's a nice special case; a radio amateur satellite that already "failed" in the early 80s and then failed a bit more, and started (sort of) working again :smile: 44 years and counting, if you include the non-operational years in between.

[URL="https://en.wikipedia.org/wiki/International_Cometary_Explorer"]ICE / ISEE-3[/URL]
Another one, lost in space, then recovered, then probably lost again. There is just no way to contact it at the moment, and the exact orbital position isn't known, and it can't be adjusted anymore as the thrusters failed in 2014. But the next chance is in 2031, and it may (or may not) still be alive then. Of course it'll be more of a curiosity by then, not really useful for any actual observations.

[URL="https://en.wikipedia.org/wiki/IMAGE"]IMAGE[/URL]
A more recent orbiter, operational from 2000 until its sudden loss in 2005. Then it was suddenly recovered by accident in 2018, but only temporarily - it's fallen silent again.

Of course, none of these cases apply to the Voyagers. When their nuclear battery runs out, they're gone forever. :sad:

PhilF 2019-02-15 01:00

[QUOTE=nomead;508592]Of course, none of these cases apply to the Voyagers. When their nuclear battery runs out, they're gone forever. :sad:[/QUOTE]

Until Kirk finds one a couple hundred years from now.

Uncwilly 2019-04-10 14:06

I just thought that it was interesting where this thread started and the current announcements about SLS going slow.
[url]https://www.forbes.com/sites/jonathanocallaghan/2019/03/17/surprise-nasa-announcement-puts-future-of-new-mega-rocket-in-doubt/[/url]
And since today is the scheduled second launch of a FH.
And more launches for the FH are scheduled for this year.
And it is within the 7 year requirement laid down in the first post.

I thought it would be a fine time to post.


Space.IL, Bennu, and Ryugu all saw action on the same day last week, too. That is awesome.

ewmayer 2019-05-03 22:00

[url=https://www.cnet.com/news/nasa-was-sold-faulty-aluminum-in-19-year-scam/]NASA was sold faulty aluminum in 19-year scam[/url] | CNET
[quote]NASA on Tuesday revealed that a pair of failed missions were caused by a 19-year aluminum scam.

The space agency previously said the 2009 Orbiting Carbon Observatory and 2011 Glory missions malfunctioned when the Taurus XL rockets’ protective nose cones failed to separate on command.

However, a joint investigation involving NASA and the Justice Department revealed that the problem was caused by aluminum extrusion maker Sapa Profiles, which falsified critical tests over 19 years.

Employees at the company’s Portland, Oregon, facilities tweaked failing tests so materials appeared to pass from 1996 to 2015, according to the Justice Department. …

Sapa, which has since changed its name to Hydro Extrusion Portland, agreed to pay $46 million to the US government and other commercial customers — which doesn’t even come close to the $700 million NASA lost as a result of Taurus XL failures.[/quote]
Sounds like more Boeing-style neoliberal "allow them to self-certify"-ness. NASA has a history of this sort of thing. True, you can't independently test every component, but how about the absolutely most mission-critical ones? The infamous Hubble flawed main mirror was similar - NASA took Perkin-Elmer's word for it that the mirror was up to spec, when a scaled-up Foucault test like that done by innumerable amateur telescope makers would have revealed the problem, and there would have been no mission delay because NASA had a ready-to-go second main mirror, a backup subcontracted by P-E to Eastman Kodak which was brought out of storage and tested after the fact and found to be fully up to spec.

retina 2019-05-04 02:54

[QUOTE=ewmayer;515686][url=https://www.cnet.com/news/nasa-was-sold-faulty-aluminum-in-19-year-scam/]NASA was sold faulty aluminum in 19-year scam[/url] | CNET[/QUOTE]Was the out-of-spec metal actually the cause of the failures? Or were NASA just looking for someone to blame, found something not-to-spec, and blamed them?

ewmayer 2019-05-06 20:39

[QUOTE=retina;515695]Was the out-of-spec metal actually the cause of the failures? Or were NASA just looking for someone to blame, found something not-to-spec, and blamed them?[/QUOTE]

Falsified test reports seem pretty damning - would the company have paid the hefty fine and agreed to be excluded from further contracting with the federal government if they had a strong "not our fault" argument? Not saying it's not possible or that NASA is blameless, mind you - hence my note about the agency's dismal track record of allowing contractors to self-certify.

retina 2019-05-07 05:48

[QUOTE=ewmayer;515964]Falsified test reports seem pretty damning - would the company have paid the hefty fine and agreed to be excluded from further contracting with the federal government if they had a strong "not our fault" argument?[/QUOTE]That depends upon the contract. If it says "anything out-of-spec then you get punished" then so be it, they f.uped. But that still doesn't mean the out-of-spec stuff actually caused any problem. The spec might have been set deliberately high (quite probably I would imagine) and then stuff marginally sub-par would still cope perfectly fine. So, no, I think the punishment does not conclusively tell us that it was the cause, just that someone did bad and they got caught.

hansl 2019-05-11 20:13

They should be accountable for the full $700mil IMO.

kriesel 2019-05-15 15:57

Metal toothpaste
 
Extruding metal is a strange yet commodity business. I had occasion in the 1990s to deal with PEI, the winner of competitive bids, for certain custom profile aluminum extrusions for frame material for the prototyping of muon chambers for the compact muon solenoid then being built for installation at CERN. Specs included tolerances on profile cross sectional shape, twist, and bow. As I recall they ran at least two batches of each profile to get some that passed my inspection. I think PEI later went bankrupt. PEI = Precision Extrusions Incorporated.
On an earlier 1983 project, for main structural components of the WUPPE telescope space shuttle payload, we avoided the whole NASA material certification rigamarole by acquiring precertified flat plate from Marshal Space Flight Center existing stock, and turned it into thick wall 24" od 2" wall tubing, as raw material for machining thin 0.2" wall ribbed shells with mating flanges, by annealing, rolling, 4-stage welding with radiography after each quarter, rough cleanup machining, stretch-forming, aging, and final machining, along with weld coupons for metallurgical samples and tensile testing. We made 3 such tubes for a project that required two finished parts, to have a spare in case of unrecoverable error. That was a crash program to replace some parts of a different design by others, that had failed to meet spec due to excessive weld distortion. Critical $30,000 parts in a $30,000,000 project; the main telescope tube mounting and spacing the main optics. The accelerated program for replacement succeeded in a few months, necessary to keep the schedule for payload assembly completion and integration onto a 4-experiment platform, in preparation for the flight after Challenger in 1986. Challenger's February 1986 loss during launch was a disaster that grounded the shuttle fleet for two years, and upon resumption, catchup on classified payloads continued the grounding of scientific payloads for an additional two years. So the WUPPE experiment that was intended to fly in March of 1986, whose launch schedule we worked frantically and creatively to save in 1983, first flew in 1990. At that time, there was no such thing as self-certification. We had to keep every record, and used one 3rd party subcontractor to inspect the work of another. WUPPE flew twice, and is now on display in a local museum, and the nspection and purchase records are still around.

retina 2019-06-25 02:23

[url]https://www.nasaspaceflight.com/2019/06/nasa-payloads-next-falcon-heavy-lz-1/[/url]

A long a informative article about the upcoming payloads and launch of the Falcon Heavy [quote]NASA has released information regarding the U.S. space agency’s payloads that will launch on the Air Force’s STP-2 (Space Test Program -2) mission on SpaceX’s Falcon Heavy rocket later this month.

[...]

The NASA payloads are: the Deep Space Atomic Clock, the Green Propellant Infusion Mission, the Space Environment Testbeds, and the Enhanced Tandem Beacon Experiment.[/quote]

rogue 2019-06-25 13:00

While driving on our vacation this year, we discovered the [URL="https://www.nasa.gov/centers/stennis/home/index.html"]John C. Stennis Space Center[/URL] less than an hour from New Orleans. None of us had ever heard of it before. This NASA site is used for testing rocket engines. Although we didn't get to see any tests we did get to see the massive structure they use to hold the rockets for those tests. We also saw a stage 1 booster from a Saturn V and various artifacts from the Apollo missions.

Uncwilly 2019-06-25 14:12

I was on vacation in 2017 and had Stennis on my list of possible locations to see. Unfortunately Hurricane Harvey made that a real poor choice. I could have gotten a friends and family tour of the place.....

firejuggler 2019-06-29 13:33

We are going to Titan (Largest moon of saturn)
A quadcopter Drone! (except it will be 3M long and weigh 450 kilos-990 pound?-), equipped with nuclear generator.
Well, launch is slated for 2026, and landing for 8 year later.

[YOUTUBE]xn3-0a19sC8[/YOUTUBE]


[URL]https://en.wikipedia.org/wiki/Dragonfly_(spacecraft[/URL])
[url]https://gizmodo.com/will-nasa-find-life-on-titan-1835956477[/url]

The question will not be 'is there a life on mars" anymore, but is there life on Titan?

tServo 2019-08-21 13:54

The Europa Clipper mission is proceeding !
 
The decision has been made to proceed with design of the spacecraft and mission.
It may be ready by 2023 but 2025 is more realistic.
BTW, Europa has TWICE the amount of water as Earth !!!!!

[URL="https://europa.nasa.gov/news/25/mission-to-jupiters-icy-moon-confirmed/"]https://europa.nasa.gov/news/25/mission-to-jupiters-icy-moon-confirmed/[/URL]
I wonder if they'll find a monolith there?
"All these worlds are yours, except Europa."

Nick 2019-08-24 10:07

"How does the law work in space?"

Press article: [URL]https://www.bbc.com/news/world-49457912[/URL]
I'm not sure they've worked out the full implications for space tourism!

Uncwilly 2019-08-27 22:15

Dragon capsule returned today.

And Starhopper completed its test flight.

chalsall 2019-09-29 23:15

"Man of steel...
 
SWMBO thinks I have a "man-crush" on Musk.

I don't; I just greatly admire the work he, and others, are doing -- just getting stuff done...

[URL="https://arstechnica.com/features/2019/09/after-starship-unveiling-mars-seems-a-little-closer/"]Elon Musk, Man of Steel, reveals his stainless Starship[/URL]...

P.S. To put on the record, I /would/ bear children for Musk, but only if he asked... :wink:

ewmayer 2019-11-18 20:15

[url=https://www.sciencealert.com/we-ve-found-a-serious-new-health-risk-to-spaceflight-that-could-make-a-mars-trip-risky]We've Found a Serious New Health Risk to Human Spaceflight[/url] | ScienceAlert

Every SciFi film from the 1950s and 60s which I can recall featuring some kind of space station had a rotating-torus one, even if the alleged corresponding interior shots were clearly incompatible with a toroidal layout, Kubrick's [i]2001[/i] being one of the very few ones which went to great pains to get details like that right. turns out that when it comes time to actual *build* such a beast, quasi-linear layouts built up from small straight-tubular modules is far, far cheaper. So if Elon Musk wants to move to his exclusive gated community on Mars in his lifetime, he's gonna have to shell out some of those tens of $billions he made off Tesla to build a rotating setup, and solve the radiation problem, to boot. But the man clearly relishes an engineering challenge...

ewmayer 2019-11-19 19:34

Followup to my above post - long story short, if you want artifical-g at a reasonable cost, use paired modules connected by a tether and sling 'em like a gaucho's bola:

[url]https://www.nakedcapitalism.com/2019/11/links-11-18-19.html#comment-3244743[/url]

Uncwilly 2019-11-19 21:43

[QUOTE=ewmayer;531007]Followup to my above post - long story short, if you want artifical-g at a reasonable cost, use paired modules connected by a tether and sling 'em like a gaucho's bola:[/QUOTE]Spent stages or fuel tanks are useful for that. If your rocket is all-in-one, then you need a pair of launches.

Dr Sardonicus 2019-12-03 14:07

Followup to [url=https://www.mersenneforum.org/showpost.php?p=525361&postcount=1049]this post[/url] in RIP

[url=https://www.theguardian.com/science/2019/dec/03/indias-crashed-vikram-moon-lander-spotted-on-lunar-surface]India's crashed Vikram moon lander spotted on lunar surface[/url][quote]A Nasa satellite orbiting the moon has found India’s Vikram lander, which crashed on the lunar surface in September, the US space agency said on Monday.

Nasa released an image taken by its Lunar Reconnaissance Orbiter (LRO) that showed the site of the spacecraft’s impact and associated debris field, with parts scattered over almost two dozen locations spanning several kilometres.

In a statement, Nasa said it had released a mosaic image of the site on 26 September, inviting the public to search it for signs of the lander.

It added that a person named Shanmuga Subramanian contacted the LRO project with a positive identification of debris – with the first piece found about 750 metres north-west of the main crash site.[/quote]More on this "person" (a 33 year old engineer in Chennai [formerly known as Madras]) [url=https://www.ndtv.com/chennai-news/chandrayaan-2-shanmuga-subramanian-chennai-engineer-alerted-nasa-about-vikram-lander-2142378]here[/url]

masser 2019-12-04 21:56

Parker Solar Probe early returns:

[URL="https://www.npr.org/2019/12/04/784761596/probe-gets-close-to-the-sun-finds-rogue-plasma-waves-and-flipping-magnetic-field"]https://www.npr.org/2019/12/04/784761596/probe-gets-close-to-the-sun-finds-rogue-plasma-waves-and-flipping-magnetic-field[/URL]

storm5510 2019-12-27 23:43

[QUOTE=Uncwilly;524686]..And Starhopper completed its test flight.[/QUOTE]

Reportedly, the next Starliner flight will be crewed and a commanding officer has been picked. I do not know what the issue was last time when it returned. Something to do with the ISS from what I gather. Either way, we need our own ride to the station so we can stop hitchhiking on Soyuz missions.

Dr Sardonicus 2019-12-28 00:49

[QUOTE=storm5510;533671]Reportedly, the next Starliner flight will be crewed and a commanding officer has been picked. I do not know what the issue was last time when it returned. Something to do with the ISS from what I gather. Either way, we need our own ride to the station so we can stop hitchhiking on Soyuz missions.[/QUOTE]See also [url=https://www.mersenneforum.org/showpost.php?p=533289&postcount=12]this post[/url] [i]et seq[/i] (click on thread title in upper right).

storm5510 2020-01-24 23:11

It would appear SpaceX is going to beat everyone. Their crew-capable Dragon passed its last test. They probably will not wait long to let humans take a ride.

Dr Sardonicus 2020-02-08 20:21

There once was a "space race." Now it's a demolition derby.
 
[url]https://apnews.com/a83a0c8b152bb8f393c1500bd3fed739[/url]
[quote]CAPE CANAVERAL, Fla. (AP) — Defective software could have doomed Boeing’s crew capsule during its first test flight, a botched trip that was cut short and never made it to the International Space Station, NASA and company officials said Friday.

The Starliner capsule launched without astronauts in December, but its automatic timer was off by 11 hours, preventing the capsule from flying to the space station as planned. This software trouble — which left the capsule in the wrong orbit just after liftoff — set off a scramble to find more possible coding errors, Boeing officials said.
Hours before the Starliner's scheduled touchdown, a second software mistake was discovered, this time involving the Starliner's service module. Flight controllers rushed to fix the problem, which could have caused the cylinder to slam into the capsule once jettisoned during reentry.

Such an impact could have sent the Starliner into a tumble, said Jim Chilton, a senior vice president for Boeing. In addition, damage to the Starliner's heat shield could have caused the capsule to burn up on reentry, he noted.

He also conceded they wouldn’t have found the second problem without the first.
<snip>[/quote]
Perhaps managers thought they could save some time, or the bean-counters thought they could save a few bucks, by not bothering to check the code before they put it in control of a billion-dollar spacecraft.

But wait -- there's more! There's short-term thinking, and then there's not having enough mental capacity to handle a no-brainer:[quote]NASA has yet to decide whether Boeing should conduct another test flight without a crew, before putting astronauts on board.[/quote]

xilman 2020-03-15 18:06

I always knew that clockwork would make a come-back.

[url]https://www.nasa.gov/feature/jpl/nasa-wants-your-help-designing-a-venus-rover-concept[/url]

I wonder if something based round a lobster eye with a photo-sensitive phase-change material would work? Use a shutter mechanism to expose the detectors and magnify the volume changes with a set of levers. The dark points when the shutters are closed would reset the detector ready for the next exposure.

Dr Sardonicus 2020-03-15 18:33

Any volunteers?
 
Ahh, a new post to this thread. Excellent! I had forgotten to post a mention of this March 6 story.

[url=https://apnews.com/32280451a00709e676438424696d8ca9]Boeing hit with 61 safety fixes for astronaut capsule[/url] (my emphasis)[quote]CAPE CANAVERAL, Fla. (AP) — Boeing faces 61 safety fixes following last year's botched test flight of its Starliner crew capsule, NASA said Friday.

NASA has also designated December's aborted space station mission as a serious "high-visibility close call" that could have destroyed the capsule — twice.

[b]In releasing the outcome of a joint investigation, NASA said it still has not decided whether to require Boeing to launch the Starliner again without a crew, or go straight to putting astronauts on board.[/b]

Douglas Loverro, NASA's human exploration and operation chief, told reporters that Boeing must first present a plan and schedule for the 61 corrective actions. Boeing expects to have a plan in NASA's hands by the end of this month.

Loverro said the space agency wants to verify, among other things, that Boeing has retested all the necessary software for Starliner.

"[b]At the end of the day, what we have got to decide is ... do we have enough confidence to say we are ready to fly with a crew or do we believe that we need another uncrewed testing[/b]," Loverro said.[/quote]They're even [i]thinking[/i] about going straight to manned flights with this thing? Or is "thinking" even the right word?

:picard:

kriesel 2020-03-15 21:11

[QUOTE=Dr Sardonicus;539789]Ahh, a new post to this thread. Excellent! I had forgotten to post a mention of this March 6 story.

[URL="https://apnews.com/32280451a00709e676438424696d8ca9"]Boeing hit with 61 safety fixes for astronaut capsule[/URL] (my emphasis)They're even [I]thinking[/I] about going straight to manned flights with this thing? Or is "thinking" even the right word?

:picard:[/QUOTE]This is the same agency that sacrificed two space shuttles with all hands and payloads in a futile attempt to maintain a much reduced schedule, and also thereby did serious damage to the schedule. Much reduced schedule from the initial unjustified hype, that is. Both catastrophic losses were the result of launches in cold January weather. At least one against engineering advice.

kladner 2020-03-16 07:49

[QUOTE=kriesel;539804]This is the same agency that sacrificed two space shuttles with all hands and payloads in a futile attempt to maintain a much reduced schedule, and also thereby did serious damage to the schedule. Much reduced schedule from the initial unjustified hype, that is. Both catastrophic losses were the result of launches in cold January weather. At least one against engineering advice.[/QUOTE]
O-rings (and political pressure) in one and ice damage in the other.

kriesel 2020-03-16 23:58

[QUOTE=kladner;539832]O-rings (and political pressure) in one and ice damage in the other.[/QUOTE]Yes. As an engineer who became one after watching Apollo missions in live prime time TV coverage, and subsequently involved in redesign and producing a shuttle payload that missed being lost by one launch date and so was delayed by 4 years, I'm very familiar with the failure mechanisms both technical and managerial. There was a consistent drive to obtain acceptable risk numbers. (The damage probability estimates were cooked at NASA to provide the desired outcomes. Repeatedly.) A professor I worked with applied to be a mission specialist, but ended up as ground support expert instead. That and timing saved his life and his instrument.

kladner 2020-03-17 03:41

Challenger:
I am convinced that pressure from the top had NASA Admin overruling the engineers on the launch parameters. The Gipper was making a speech that night. It would be in character for him to point at the ceiling and husk out, "At this moment a Teacher in Space is inspiring our KIDS!"
He probably got more mileage out of the Sad Announcement, and made the Teacher in Space into The Martyr who never made it to Space.

There is a short story involving one of the Morton Thiokol engineers who was so guilt-stricken by the disaster that he arranged shaped charges to blow the wings off the Morton Thiokol corporate jet (with him and the administrators on board) at an altitude which would have the occupants falling for the same length of time as the astronauts. When the charges go off he is finally at peace.

Maybe someone like Allan McDonald was an inspiration for the story.
[URL]https://www.nasa.gov/centers/langley/news/researchernews/rn_Colloquium1012.html[/URL]

Uncwilly 2020-03-31 03:23

Xilman (aka Paul) what are your thoughts on this?
[url]https://www.centauri-dreams.org/2020/03/27/introducing-the-q-drive-a-concept-that-offers-the-possibility-of-interstellar-flight/[/url]

chalsall 2020-04-05 19:18

[QUOTE=Uncwilly;541382]Xilman (aka Paul) what are your thoughts on this?[/QUOTE]

I would also be very interested in hearing any thoughts on this by people who understand these kinds of spaces (no joke intended) better than I do.

xilman 2020-04-05 22:51

[QUOTE=Uncwilly;541382]Xilman (aka Paul) what are your thoughts on this?
[url]https://www.centauri-dreams.org/2020/03/27/introducing-the-q-drive-a-concept-that-offers-the-possibility-of-interstellar-flight/[/url][/QUOTE]I took a quick look but haven't studied it in enough detail to say how likely it is to be built.

The Newtonian mechanics is straightforward but the engineering is anything but. Ensuring that the exhaust velocity is the same (or near enough within acceptable efficiency) as the wind velocity is likely to be much harder. Even if the mean exhaust velocity can be matched precisely, which is far from obvious to me, it is not clear to me how the inevitable velocity dispersion will affect the efficiency of the drive.

I see how the Mercury orbiter mission works; I do not yet see how to do anything but a fly-by of anything further out from the sun. The latter are valuable, of course, but it would be nice to have a Neptune orbiter for instance.

OTOH, a flight along the solar gravitational focal line could be [I]very[/I] interesting.

I should think about how to implement fuel-efficient brakes...

chalsall 2020-04-13 18:47

[QUOTE=xilman;541908]I should think about how to implement fuel-efficient brakes...[/QUOTE]

Could a bounced laser beam be of any use?

Have a huge light-sail which is used to accelerate towards the target. Then when you get near your destination, a smaller sub-section of the sail from the center separates. This then continues to get the (now lesser) impulse from the light-source, and the (greater) bounced (and, importantly, focused) photos off of the (expendable) larger section.

I assume the idea has been discussed before (both "hard" sci-fi, and real-world feasibility analysis). Should work, but you'd need /many/ *very* powerful lasers in Earth (or some) orbit -- would make a nice weapon in the wrong hands...

xilman 2020-04-13 19:23

[QUOTE=chalsall;542547]Could a bounced laser beam be of any use?

Have a huge light-sail which is used to accelerate towards the target. Then when you get near your destination, a smaller sub-section of the sail from the center separates. This then continues to get the (now lesser) impulse from the light-source, and the (greater) bounced (and, importantly, focused) photos off of the (expendable) larger section.

I assume the idea has been discussed before (both "hard" sci-fi, and real-world feasibility analysis). Should work, but you'd need /many/ *very* powerful lasers in Earth (or some) orbit -- would make a nice weapon in the wrong hands...[/QUOTE]This approach is well known in the specialist literature but, perhaps, not more widely. I could try to dig up references for those interested.

However, my response was within the context of the drive in question as opposed to, say, sails.

Weapons: such devices would be very fragile because of their power requirements. Either they have on-board fusion sources, in which case earth-bound counterparts could take them out with ease as tight beamwidths are not needed, or they would rely on the pitifully feeble ~1kW/m^2 solar power density in these parts and an asat would be sufficient. Even in Mercury orbit the power density is only ten times greater. Even today the likes of India could fly an effective asat.

chalsall 2020-04-13 19:47

[QUOTE=xilman;542557]Either they have on-board fusion sources, in which case earth-bound counterparts could take them out with ease as tight beamwidths are not needed...[/QUOTE]

I don't entirely understand this statement. (Love the conversation though -- I learn something every time! :smile:)

Are you saying an adversary could overwhelm the thermal radiation that such a power-plant would require? Wouldn't that "kit" need to be in a higher orbit, since presumably the radiators would be pointed away from Earth?

Or am I missing something obvious?

xilman 2020-04-13 20:00

[QUOTE=chalsall;542558]Or am I missing something obvious?[/QUOTE]I suspect so.

The power density for a feasible interstellar sail would be high enough to fry any unprotected installation. A tiny probe can be made very reflective and is tiny. A multi-square kilometre collecting array (1 km^2 collects around 1GW and an interstellar probe will likely need more than that to get anywhere in a reasonable time) is likely to be much more difficult to protect.

An earth-bound TW laser need only have an beamwidth of a few arcsec (assuming it is atmosphere limited) and can easily deliver GW/m2 to earth orbit. Enough to vaporize anything, protected or not.

Xyzzy 2020-04-14 11:14

[URL]https://www.bbc.com/news/science-environment-52264743[/URL]

:mike:

kriesel 2020-04-18 13:10

[QUOTE=xilman;542560]I suspect so.

The power density for a feasible interstellar sail would be high enough to fry any unprotected installation. A tiny probe can be made very reflective and is tiny. A multi-square kilometre collecting array (1 km^2 collects around 1GW and an interstellar probe will likely need more than that to get anywhere in a reasonable time) is likely to be much more difficult to protect.

An earth-bound TW laser need only have an beamwidth of a few arcsec (assuming it is atmosphere limited) and can easily deliver GW/m2 to earth orbit. Enough to vaporize anything, protected or not.[/QUOTE]
A GW is a large generating plant. A TW is a little more than twice the US mean stationary electrical generation. TW laser output implies multi-TW input. [URL]https://www.eia.gov/energyexplained/electricity/electricity-in-the-us-generation-capacity-and-sales.php[/URL]
And the oft advocated method of increasing or replacing grid capacity has its down sides. [URL]https://foreignpolicy.com/2019/09/06/the-path-to-clean-energy-will-be-very-dirty-climate-change-renewables/[/URL]
Energy storage challenges are even greater. [url]http://css.umich.edu/factsheets/us-grid-energy-storage-factsheet[/url]

Could be a fun project, if you had the financial support of Bill Gates, Elon Musk, Jeff Bezos, George Soros, Michael Bloomberg, etc. or a large portion of the US defense budget, and no concern about global warming from the multiple TW increase in waste heat. [URL]https://www.quora.com/What-would-happen-if-I-had-a-1-terawatt-laser-outputting-constantly-How-big-would-it-be-and-how-powerful-would-it-be-What-about-a-petawatt-laser-And-a-yottawatt-laser?share=1[/URL]
Or go maser. [URL]https://en.wikipedia.org/wiki/Astrophysical_maser[/URL]

xilman 2020-04-18 13:32

[QUOTE=kriesel;543054]A GW is a large generating plant. A TW is a little more than twice the US mean stationary electrical generation. TW laser output implies multi-TW input.[/QUOTE]You are quite correct but...

Generating peak powers in the TW range is much easier for a pulsed laser than for one operating in CW mode.

Petawatt lasers have been in operation for over thirty years. [url]https://en.wikipedia.org/wiki/Vulcan_laser[/url] is an example. [url]https://www.extremetech.com/extreme/290863-massive-10-petawatt-laser-can-vaporize-matter[/url] is a 10PW laser.

retina 2020-04-26 21:42

How Space Tries to Kill You and Make You Ugly

Oh also, it makes you blind and stupid, too.

[url]https://www.wired.com/story/how-space-tries-kill-you-make-you-ugly/[/url] [quote]Outer space is the most noxious of substances: devoid of air and filled with a soup of deadly particles in the form of high-energy photons and energetic bits of atomic nuclei. The lack of gravity there affects every element of your being, as even the proteins in your body can’t figure out which way is up.[/quote]

kriesel 2020-04-27 02:57

A rough calculation from numbers in [URL]https://en.wikipedia.org/wiki/Saturn_V[/URL] indicates the 159 seconds burn of the first stage after liftoff averages about 12.5 GW of gravity work and addition of kinetic energy to its upper stages. (So, neglecting drag on the whole craft, and gravity work and kinetic energy on the first stage.) Factoring in the mass of the emptied first stage, brings it to over 15GW average. The peak is clearly considerably higher. Computing an estimate of peak effective power based on thrust times final stage 1 velocity yields 75 GW. [URL]https://en.wikipedia.org/wiki/Saturn_V[/URL]
A typical nuclear power station unit is around 1 GWe. The world had 450 as of 2014.
[URL]https://en.wikipedia.org/wiki/List_of_nuclear_power_stations[/URL]

xilman 2020-04-27 08:25

[QUOTE=kriesel;543909]A rough calculation from numbers in [URL]https://en.wikipedia.org/wiki/Saturn_V[/URL] indicates the 159 seconds burn of the first stage after liftoff averages about 12.5 GW of gravity work and addition of kinetic energy to its upper stages. (So, neglecting drag on the whole craft, and gravity work and kinetic energy on the first stage.) Factoring in the mass of the emptied first stage, brings it to over 15GW average. The peak is clearly considerably higher. Computing an estimate of peak effective power based on thrust times final stage 1 velocity yields 75 GW. [URL]https://en.wikipedia.org/wiki/Saturn_V[/URL]
A typical nuclear power station unit is around 1 GWe. The world had 450 as of 2014.
[URL]https://en.wikipedia.org/wiki/List_of_nuclear_power_stations[/URL][/QUOTE]An alternative way of looking at it: the astronauts were sitting on top of a device with the explosive yield roughly half that of those which were used at Hiroshima and Nagasaki.

A major reason why the sightseers were several kilometres away.

retina 2020-04-27 09:05

[QUOTE=xilman;543928]An alternative way of looking at it: the astronauts were sitting on top of a device with the explosive yield roughly half that of those which were used at Hiroshima and Nagasaki.

A major reason why the sightseers were several kilometres away.[/QUOTE]Although the energy release mechanisms are very different.

A typical power bank has more stored energy than a hand grenade, but I know which one I'd much rather be near to when it is in use.

kriesel 2020-04-27 10:15

It takes a special kind of person to sit atop all that fuel and oxygen, knowing that every bit of it was built by a low bidder, and what happened to Grissom, Chaffee, and White. [URL]https://www.spaceanswers.com/space-exploration/an-interview-with-nasas-chief-photographer-bill-ingalls-the-man-behind-the-camera/[/URL]
Or to take a space shuttle up the time after the Challenger disaster. Sitting not atop but next to a giant fuel tank the equal of which had killed a previous crew. Or was it the managers. [URL]https://www.britannica.com/event/Challenger-disaster[/URL] "The Rogers Commission heard disturbing testimony from a number of engineers who had been expressing concern about the reliability of the seals for at least two years and who had warned superiors about a possible failure the night before 51-L was launched."
Or after the loss of Columbia during return. [URL]https://www.space.com/19436-columbia-disaster.html[/URL] "An investigation board determined that a large piece of foam fell from the shuttle's external tank and breached the spacecraft wing. This problem with foam had been known for years, and NASA came under intense scrutiny in Congress and in the media for allowing the situation to continue."

Dr Sardonicus 2020-04-27 12:04

[QUOTE=kriesel;543931]It takes a special kind of person to sit atop all that fuel and oxygen, knowing that every bit of it was built by a low bidder, and what happened to Grissom, Chaffee, and White.[/QUOTE]
I seemed to recall hearing decades ago that John Glenn had said something about the low bidder. It took me very little time to find the following quotes attributed to him. No specific citation, though.

[quote]As I hurtled through space, one thought kept crossing my mind - every part of this rocket was supplied by the lowest bidder.[/quote]
and
[quote]I guess the question I'm asked the most often is: "When you were sitting in that capsule listening to the count-down, how did you feel?" Well, the answer to that one is easy. I felt exactly how you would feel if you were getting ready to launch and knew you were sitting on top of two million parts -- all built by the lowest bidder on a government contract.[/quote]
We also have the following:
[quote]If we die, we want people to accept it. We are in a risky business and we hope that if anything happens to us it will not delay the program. The conquest of space is worth the risk of life.[/quote] - Virgil I. "Gus" Grissom, after the Gemini 3 mission, March 1965

I note that, after The Fire on January 27, 1967 the Apollo capsule was completely redesigned and rebuilt, preparatory Apollo missions flown, and Apollo 11 took the first men to the Moon and back -- within about two and a half years.

Uncwilly 2020-04-27 13:54

[QUOTE=kriesel;543931]Or to take a space shuttle up the time after the Challenger disaster. Sitting not atop but next to a giant fuel tank the equal of which had killed a previous crew. [/QUOTE]It was not the giant tank that killed the astronauts. Impact of the crew cabin with the Atlantic Ocean is what killed them. Working backward form that, the break-up of the orbiter, then the break-up of the tank as the attachment of the orbiter, then the loss of structural integrity near the aft bulkhead, then flame impingement on the ET (External Tank), then failure of the field joint (I have put my hand in one), then back to the failure of the O-ring. The tank did not kill the astronauts, rather the impact or the O-ring. There was no "explosion" of the cryogenics. No shockwave from that sort of even is observed.

retina 2020-04-27 13:58

[QUOTE=Uncwilly;543944]... then flame impingement on the ET ...[/QUOTE]ET? Extra Terrestrial?

[size=1]So it was aliens that did it! [/ConspiracyTheory][/size]

Uncwilly 2020-04-27 14:05

[QUOTE=retina;543945]ET? Extra Terrestrial?[/QUOTE]That large orange thing stuck to the bottom of the orbiter.

xilman 2020-04-27 16:42

[QUOTE=retina;543930]Although the energy release mechanisms are very different.

A typical power bank has more stored energy than a hand grenade, but I know which one I'd much rather be near to when it is in use.[/QUOTE]Yup.

That said, it is rather difficult to release the energy stored in a power bank over the few milliseconds typical of the life time of an active hand grenade. It was rather easy to release 8kt explosive yield in a Saturn V within a few seconds and the immediate effect would have been much the same as that experienced in Japan though, thankfully, without the long-term side-effects.

kriesel 2020-04-27 17:47

[QUOTE=Uncwilly;543944]It was not the giant tank that killed the astronauts. Impact of the crew cabin with the Atlantic Ocean is what killed them. Working backward form that, the break-up of the orbiter, then the break-up of the tank as the attachment of the orbiter, then the loss of structural integrity near the aft bulkhead, then flame impingement on the ET (External Tank), then failure of the field joint (I have put my hand in one), then back to the failure of the O-ring. The tank did not kill the astronauts, rather the impact or the O-ring. There was no "explosion" of the cryogenics. No shockwave from that sort of even is observed.[/QUOTE]My bad.
I remember at the time of the Challenger accident, coworkers wanting to believe there was an explosion and instant death. I knew immediately from engineering background that both the crew cabin was a pressure vessel that would provide some protection, and at the time of catastrophe they were in supersonic motion so any shock wave of an explosion would be somewhat attenuated.A recent rereading of the sequence of events showed what may have killed the crew was loss of atmosphere in the cabin, or ocean impact. The uncontrolled combustion of the released contents of the external tank was described as a fireball, not an explosion. Initially the cabin coasted upward. The impact of the cabin with the ocean surface was minutes later, and so damaging to cabin and crew that the investigation came to no conclusion about the mechanism of their deaths. There was enough time for the onboard electronics to record one of the crew saying uhoh after things went seriously bad and they knew it, before the onboard power went out. There were also other signs of activity performed probably after the cabin detached.They knew they were in trouble, at least briefly. [url]https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disaster#January_28_launch_and_failure[/url]

kriesel 2020-04-27 17:58

[QUOTE=Uncwilly;543946]That large orange thing stuck to the bottom of the orbiter.[/QUOTE]Bottom seems imprecise for a craft that initiates atmospheric reentry at 40 degree pitch angle of attack, launches vertical, and often orbited with the payload bay facing earth. The orbiter stands vertical on the launch pad. Nearest the launch pad are 3 liquid fueled rocket engines that receive fuel and oxidizer from the external tank, and a tail fin. The external tank is adjacent to the orbiter's ventral surface, the surface that is the bottom surface in reentry glide and landing and has retractable landing gear. [url]https://en.wikipedia.org/wiki/Space_Shuttle#/media/File:Space_Shuttle_Orbiter-Illustration.jpg[/url]
Initially the single-use external tanks were also painted white. Then someone advocated for not painting such tanks, pointing out leaving off the paint saved 600 pounds of mass. The color of the external tank is unprotected spray-on insulation.

chalsall 2020-04-27 18:09

[QUOTE=kriesel;543970]A recent rereading of the sequence of events showed what may have killed the crew was loss of atmosphere in the cabin, or ocean impact.[/QUOTE]

I don't have references immediately at hand, but I've read from credible sources that several of the emergency oxygen supplies were activated, and used, during the decent.

Dan Simmons' [URL="https://en.wikipedia.org/wiki/Prayers_to_Broken_Stones#%22Two_Minutes_Forty-five_Seconds%22"][I]Two Minutes Forty-five Seconds[/I][/URL] short story in his [I]Prayers to Broken Stones[/I] collection coldly covers the topic.

kriesel 2020-04-27 18:21

[QUOTE=chalsall;543973]I don't have references immediately at hand, but I've read from credible sources that several of the emergency oxygen supplies were activated, and used, during the decent.

Dan Simmons' [URL="https://en.wikipedia.org/wiki/Prayers_to_Broken_Stones#%22Two_Minutes_Forty-five_Seconds%22"][I]Two Minutes Forty-five Seconds[/I][/URL] short story in his [I]Prayers to Broken Stones[/I] collection coldly covers the topic.[/QUOTE]Yes, 3 of 4 PEAPs on the flight deck, including the captain's which required someone else to switch it on. Not adequate for the whole descent though. Also other indications of post-failure activity (switch changes etc.)
[URL]https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disaster#Cause_and_time_of_death[/URL]

Managers should be subjected to a lottery system for facing the risks they create when overruling the engineers, or required to personally notify the next of kin and cover the cost of burial out of their own pockets.

Uncwilly 2020-04-27 20:20

[QUOTE=kriesel;543972]Bottom seems imprecise .....[/QUOTE]If I showed a photo of the STS stack to a 3 year old and asked them to point to the "big orange thing" that they would have a problem finding it?
Also, toward the engines was "aft". When in space they used X, Y, Z axis nomenclature. Z went down, not aft. Underside is also a common term used for the bottom of the orbiter. Stop trying to over [U]anal[/U]-ize a flippant response to a flippant question.


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