Deep Space and Interplanetary Exploration - The Universe is Timeless

[Sabelkatten]

Impactors - especially high-precision ones - look great on paper, but they're extremely hard to develop (organizationally) and introduce because the topic branches over quite deeply into military applications, and because the failure rate is pretty steep. ESA for example has consistently rejected proposed impactor missions.

True, thought at least as I read it in this case the impactors aren't designed to penetrate anything - that is, they're just a way to make a cheaper landing system by making the ground a shock absorber. :)

[ANS Kamas P81]

Posing trouble for future development, being outside on Mars when a comet passes could be bad.  The magnetic field's so weak that when Siding Spring flew past and gave the place a shower, the ionized particles in the coma and tail (yes it got that close) were enough to seriously pooch Mars' quite weak magnetic field.  Certainly puts a new consideration on living there, that's for sure.

[kato]

"Close" is relative for a comet tail. Comet tails reach up to one AU length, i.e. even a comet flying right by Earth in the appropriate orbital setup could still easily hit Mars with its tail.

[Sabelkatten]

When I saw The Martian one of my first reactions were "Why did he come up with a ridiculous storm when he could just have used a meteor strike?". ::)

[kato]

ExoMars TGO and Schiaparelli lifted off successfully btw. On the 181st anniversary of Giovanni Schiaparelli's birth.

Last burn maneuver of Briz-M stage was about 2.5 hours ago, raising the stack to a high elliptic orbit. Interplanetary insertion burn is scheduled for 19:47 UTC (i.e. in three hours), 25 minutes later TGO will separate from the Briz-M stage.

[Maingunnery]

Posing trouble for future development, being outside on Mars when a comet passes could be bad.  The magnetic field's so weak that when Siding Spring flew past and gave the place a shower, the ionized particles in the coma and tail (yes it got that close) were enough to seriously pooch Mars' quite weak magnetic field.  Certainly puts a new consideration on living there, that's for sure.

Such hazards always make me think that the habitat sections for Lunar and Martian colonies should be subterranean. 

[ANS Kamas P81]

"Close" is relative for a comet tail. Comet tails reach up to one AU length, i.e. even a comet flying right by Earth in the appropriate orbital setup could still easily hit Mars with its tail.

Close is relative, yeah, but in this case it wasn't just the tail but the coma of the comet that contacted Mars.  Closest approach was under 90,000km; that's spitting distance as far as astronomy goes.

[worktroll]

When I saw The Martian one of my first reactions were "Why did he come up with a ridiculous storm when he could just have used a meteor strike?". ::)

Why 'ridiculous storm'? Mars experiences massive dust storms every Martian summer (~ 2 earth years). Sometimes the dust-storms obscure the whole planet, even covering Mons Olympus. The air might be thin, but that much dust has its own momentum.

W.

[kato]

ExoMars TGO/EDM has successfully entered interplanetary cruise phase.

Separation of TGO and EDM will occur on Oct 19th, high-elliptic orbital insertion for TGO and landing for EDM three days later.

[ANS Kamas P81]

Here's to a happy Halloween for ESA.

[Sabelkatten]

Why 'ridiculous storm'? Mars experiences massive dust storms every Martian summer (~ 2 earth years). Sometimes the dust-storms obscure the whole planet, even covering Mons Olympus. The air might be thin, but that much dust has its own momentum.

Somebody pointed it out upthread - Yes it has momentum, and IIRC you can get speeds several times higher than on Earth...

But it's the Martian atmosphere. "A lot of dust in the air" doesn't mean a whole lot on Mars, it only takes the density up to a few percent of Earth's. Which means the momentum of worst storms won't effectively be more than a stiff breeze...

[worktroll]

A lot of eroded rock disagrees with you - aeolian erosion is a real thing. Density is already a percent of Earth's - you add anything, it's gone up.

And don't forget F=MV² - double the speed, quadruple the force.

Dust storms work just like hurricanes - they rely on the temperature differential between shaded ground & sunwarmed ground. Hurricanes get their energy from hot seawater (which is why they tend to fade once over land). The dust-storms are strong enough weather systems to cross Mars' equator - something even the biggest hurricane has failed to do on Earth - and cover the whole planet.

I haven't seen the film, and it may well be that the debris sizes shown are not possible. But I sure wouldn't want to be out in the open when one hit.

W.

[Daryk]

Eh?  It's been more than 20 years since my last physics course, but last I checked, F=ma, and kinetic energy=(1/2)mv²...

[Natasha Kerensky]

The Fact and Fiction of Martian Dust Storms

It is unlikely that even these dust storms could strand an astronaut on Mars, however. Even the wind in the largest dust storms likely could not tip or rip apart major mechanical equipment. The winds in the strongest Martian storms top out at about 60 miles per hour, less than half the speed of some hurricane-force winds on Earth.

Focusing on wind speed may be a little misleading, as well. The atmosphere on Mars is about 1 percent as dense as Earth’s atmosphere. That means to fly a kite on Mars, the wind would need to blow much faster than on Earth to get the kite in the air.

http://www.nasa.gov/feature/goddard/the-fact-and-fiction-of-martian-dust-storms

[ANS Kamas P81]

Looks like the "Em-Drive" is still giving weird enough responses that the Eagleworks guys are pressing forward - this time with a full peer-review paper of their current findings.  Paul March is legit at NASA, and "Doctor White" is most likely Doctor Harold G. White who's running the Advanced Propulsion lab.  They're serious at NASA about what they've got, and even if it's too bloody weak to become useful, the mere fact it exists means there's a new part of the universe that our current theory doesn't cover yet and it's time to find out why.

Hopefully we get good answers to both soon.

[Sabelkatten]

I'm still skeptical, but I agree it's worth investigating!

[HobbesHurlbut]

And we gained lots of painful and fairly expensive experience on the process of anchoring to a low gravity body of difficult to determine consistency.  Next mission of similar scope should yield better results. 

Failure has many differing grades.

A thousand failure enrich one more than a single success does, if one is willing to learn.

[Sabelkatten]

I wonder if it might be worthwhile to put an ion thruster on a meteor lander? The gravity is really low after all, so it might be possible to use a thruster to keep the probe in position (or move it, if it ends up in the wrong place). Would provide a bit more endurance than a chemical (or compressed gas) thruster.

[kato]

Couple presentations on AIM: https://indico.esa.int/indico/event/133/other-view?view=standard

[kato]

P.S.: With regard to small asteroid landers see these four among the above:

https://indico.esa.int/indico/event/133/contribution/5/material/0/0.pdf
https://indico.esa.int/indico/event/133/contribution/36/material/0/0.pdf
https://indico.esa.int/indico/event/133/contribution/31/material/0/0.pdf
https://indico.esa.int/indico/event/133/contribution/40/material/0/0.pdf

Especially the latter three are directly "learned lessons applied" from Philae.

[Wrangler]

New space module going be tested in space.  Reported on the verge, there a video of how the BEAM module will work.

This is a Bigelow inflatable type module.  Bigelow been pushing this design for long time, it was originally NASA project dropped like the space lifeboat when station was originally being designed/built.

It's pretty neat concept, takes less the space to store before deploying, but i have reservations on how well it will do when micro impacts hit the thing.

[BirdofPrey]

Oh Bigelow is finally going to get to fly their module to the space station?

[kato]

It's mostly "useful" for how BEAM is deployed. Meaning brought up in the cargo trunk of a regular supply flight, as anything NASA for ISS currently is.

The current flight is only a conceptual test. BEAM will be mounted to ISS for two years and will during this time not be used in any way. The ISS crew has eight visits during those 24 months scheduled to check its structural integrity, and otherwise sensors will monitor integrity (air pressure), radiation load and temperature. After those two years it will be dumped into the atmosphere.

The downside of BEAM and other collapsible modules is that effectively they only provide empty space - while there's a need for that (part of the Japanese module is used like that - for storage, mostly), there's only so much you can really do with it. At best they'd provide mounting points for equipment later brought onboard by other flights for on-orbit assembly. At which point you can wonder whether it wouldn't be cheaper to package that into a standard module and launch on a dedicated flight.
What in my opinion collapsible modules similar to BEAM would mostly be interesting for would be a replacement of Progress for disposal purposes. Basically a pressurized trash bag that you can fill up for a few months and then either send into the atmosphere to burn up or set aside where it doesn't get in the way once it's full. Probably should be (slightly) smaller and (considerably) lighter than BEAM for that purpose.

[Sabelkatten]

As I understand it one major reason for using an inflatable module is material - With air pressure doing the job of making the walls stiff you can get away with using much lighter walls.

Also, if you're launching from Earth a solid module has to either be strong enough to take the forces itself or be carried in a container that does. That adds a lot of structural weight that you won't need once you're up in freefall.

[ANS Kamas P81]

http://gizmodo.com/ready-to-edit-something-just-slammed-into-jupiter-1767726856 (possible NSFW content)



Thank you Jupiter!  That looks like one hell of a big impactor from the flash, and while it looks tiny remember that Big J is 88,000+ miles across.  No banana for scale on this one.

[worktroll]

Darn! I left the keys in the saucer's ignition again ...

This will be very frustrating to planetary astronomers. It's great that this got captured, but ... like finding an archeological item out of context, much information is lost.

Mind you, if they wanted confirmation, waiting half a revolution & seeing the "bruises" in the upper cloud decks would have done nicely.

W.

[Weirdo]

How long is Jupiter's day? Has that rotation happened yet?

Also, what this is teaching me? Floating cities in Jupiter's upper atmosphere - BAD idea.

[ANS Kamas P81]

How long is Jupiter's day? Has that rotation happened yet?

Also, what this is teaching me? Floating cities in Jupiter's upper atmosphere - BAD idea.

Just under 10 hours for a day.  They might not have been able to get that; it'd be at least 5 hours after the initial impact for it to even show up on the opposite side of the planet, and 7+ to get it in a good imageable position.  They may not have known what they had at the time, so it's a good question.

Damn shame Juno wasn't present for that one; she'll be there on July 4 and maybe we'll get lucky to capture another impact from a much closer view.

[worktroll]

10 hours, off the top of my head. Winds move fast there.

Two competing thoughts on Bespins -
- Jupiter's so huge, the odds of any collision affecting you are not going to be much different than living in Texas anyway.
- OTOH, Jupiter sucks - it's got a huge gravitational capture field. The solar system can reasonably accurately be described as "The Sun, Jupiter, plus debris".

What I really want to see is something slam into one of the Gallelian moons - preferably with probes on hand. Want to know what's under 100km of Europan ice? Wipe it off the RTG ...

W.

[Weirdo]

10 hours, off the top of my head. Winds move fast there.

Okay, first, HOLY ******.  :o

Two competing thoughts on Bespins -
- Jupiter's so huge, the odds of any collision affecting you are not going to be much different than living in Texas anyway.

Problem is, a Jovian Bespin would be essentially a city-sized mobile home, and people in Texas know what that does for your impact odds. And when any impact means auto-death for hundreds or thousands? I'll try Saturn instead, so the Sol system's biggest trailer park at least won't be sitting at the bottom of Tornado Gravity Well.