Dawn taking chem makeup data at 385 km

Discussions ranging from space technology, near-earth and solar system missions, to efforts to understand the large-scale structure of the cosmos.

Re: Speed rel Ceres 53 m/s @ 56 kkm (nearing capture)

Postby Marshall on March 4th, 2015, 3:24 am 

A propos colonization, there is a Wikipedium http://en.wikipedia.org/wiki/Colonization_of_Ceres

Much of the article has been challenged as unreliable by Wik's internal review.

==some excerpts==
Ceres has been proposed as one possible target for human colonization in the inner Solar System.
... Observations indicate that it contains large amounts of water ice,[2][3]... The solar irradiance of 150 W/m2 at aphelion, one ninth that on Earth, is high enough for solar-power facilities.[1]...

Its colonization... could become a step on the way to the colonization of the objects in the outer Solar System, such as the moons of Jupiter. Because of its small escape velocity combined with large amounts of water ice, it also could serve as a source of water, fuel, and oxygen for ships going through and beyond the asteroid belt.[1]

The establishment of a permanent colony on Ceres might precede colonization of the Moon or Mars because the far deeper gravity wells of those bodies add dramatically to the cost and risk of colonization...
==endquote==

I must have groundhog instincts because I never picture SURFACE colonization of Ceres, I always think subsurface ice cavern habitats, providing protection from radiation, meteorite damage, and accidental loss of air pressure.

The Wik article cites http://eltamiz.com/files/ceres3.pdf, which is tagged as an unreliable source. Personally I found the source to be better described as visionary: reliable, that is, in its own kooky way.
Marshall
 


Re: Speed rel Ceres 53 m/s @ 56 kkm (nearing capture)

Postby Darby on March 4th, 2015, 8:29 am 

I wont even dignify the proposal by reading it, because although there is a real need for a nearby off-planet base, the choice of ceres is gobsmackingly laughable.
Darby
 


Re: Speed rel Ceres 51 m/s @ 57 kkm (nearing capture)

Postby Marshall on March 4th, 2015, 3:25 pm 

Darby » Wed Mar 04, 2015 5:29 am wrote:I wont even dignify the proposal by reading it, because although there is a real need for a nearby off-planet base, the choice of ceres is gobsmackingly laughable.


Ceres is not near by. It orbits at 3 AU from the Sun. So it is not in the running for a "nearby off-planet base".

What prospects and rationale do you see for a nearby off-planet base? Are you thinking of a base staffed purely by robots, or with humans stationed there as well? So far we seem to be doing surprisingly well with robotic extensions of our fleshy civilization.

BTW Darby! Do you see ORION in the upper left corner of the current status view?

I think sun would be out past the upper left corner and would appear in the simulated view if the frame were expanded to include a wider angle.
Marshall
 


Re: Speed rel Ceres 51 m/s @ 57 kkm (nearing capture)

Postby Darby on March 4th, 2015, 4:40 pm 

BTW, I apologize if my startled skepticism at the idea of ceres somehow being a viable candidate came across as snarky. Not intentional.

Ceres is not near by. It orbits at 3 AU from the Sun. So it is not in the running for a "nearby off-planet base".


I think a closer look at my prior post above will make it clear I did not suggest ceres was nearby - quite the opposite ... its one of the reasons why I find it a non starter.

As for a more reasonable candidate, and some rationale, I mentioned the moon earlier today over in the Mars Thread.
Darby
 


Re: Speed rel Ceres 51 m/s @ 57 kkm (nearing capture)

Postby Marshall on March 4th, 2015, 8:54 pm 

thanks for the link to the Mars thread! I found your post---the most recent one on the thread. I'll get a direct link to it in a moment in case anyone else wants to refer. I should apologize if I gave the impression that I was correcting you about Ceres being nearby :^) Of course it is not nearby! We all know that. I was just making the obvious point that it is NOT IN COMPETITION for an initial nearby manned base.

Often I think space discussion is colored by people taking sides advocating this or that in a competition for hypothetical near-term resources. Mainly I guess between Moon and Mars. I don't have a dog in that fight :^D

I see no point in arguing against Ceres as interesting in the longer term as a place humans might actually WANT to live. Lots of water. Low gravity. Little or no need for space suits and artificial sealed containers, so habitat more expandable as the population grows. Parts of the 100 km thick icy mantel might eventually be honeycombed with caves and tunnels where people LIKE to live and where they like to raise families. Two problems to solve would be A. energy--an expandable power supply and B. health in 3% of Earth gravity. (genetic modification might be requred)

Darby you know a lot of the geology---Ceres albedo is very dark: 10% I believe. Doesn't that suggest carbonaceous material? What is the chemical composition of the dark crust covering the icy mantel likely to be?

I see Moon and Mars as less suitable for humans and more suitable for robots (who don't object to a dry airless environment). they well adapted to living in dry vacuum and we aren't, so let them predominate there. survival of the fittest :^) AFAICS if you want to ACCOMPLISH anything on Moon or Mars, then it's simple build better robots. And send them to accomplish it. We already do this and it seems to be working.

Here's a direct link to your post in the Mars thread:
http://www.sciencechatforum.com/viewtop ... 23#p277299
I hope others check it out. I can understand where you are coming from since you mention interstellar diaspora. You see a manned base on the Moon as a step in that direction.

My picture of the first diaspora wave is entirely robotic. Look icy worlds, take along human DNA or frozen zygotes, set down, drill in, create a safe cave with artificial light, then hatch some humans (and possibly some other plants and animals) to live in it. That way the humans don't have to endure a long boring interstellar trip. I see Ceres as the perfect world to PRACTICE on (but without need for the frozen zygote business). I mean practicing the bit about robotically setting down and drilling in and hollowing out a place to live. Before the settlers arrive. Probably small nuclear reactors are needed. Plenty of technical problems to solve.
Marshall
 
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Re: Speed rel Ceres 50.0 m/s @ 58.4 kkm (nearing capture)

Postby Marshall on March 5th, 2015, 12:53 am 

As of 11pm pacific, current status shows speed 50.0 m/s and distance 58.4 kkm.
This on track as to speed but the distance is a little bigger than was earlier projected at this stage. Here's our table giving projected schedule for capture on 6 March:
Code: Select all
date      X          Y          Z        distance  v_esc  v_probe
F25     5.62894    25.0851    -29.7158    39.29    56.67    71.36
F26     11.407    26.4613    -29.1488    40.98    55.48      69.67
F27     17.2899    27.6663    -28.1919    43.11    54.10     68.44
F28     22.8583    28.5286    -27.0313    45.46    52.68    64.25
M1      27.9985    29.1842    -25.6846    47.90    51.32     60.73
M2      32.8862    29.7513    -24.1873    50.51    49.98     58.67
M3      37.6439    30.1647    -22.7166    53.31    48.65     55.28
M4      41.9734    30.4246    -21.3167    56.05    47.44     50.18
M5      45.8274    30.5605    -19.8726    58.55    46.42     46.96
M6      49.5028    30.6491    -18.2955    61.02    45.47     44.35
M7      52.8252    30.4896    -16.7451    63.24    44.66     40.49
M8      55.7681    30.3242    -15.1946    65.27    43.97     37.71

Some explanation:
X Y Z are coordinates relative to Ceres, which is (0,0,0), measured in kkm---thousands of km.
X is directed out from sun, in Ceres orbit plane
Y is directed perpendicularly up off the orbit plane, approximately in Ceres' north pole direction
Z is directed forwards in Ceres orbit plane, the direction Ceres is moving, a negative shows the probe trailing behind.
distance from Ceres continues increasing for a while because the probe has some excess momentum
vescape is the escape velocity at that given distance
vprobe is the predicted velocity the probe will actually have that day. It must fall below vesc to achieve capture.

You can see that for 4 March the reported speed 50.0 m/s is right but the distance 58.4 is a bit larger than the table's 56
I think what that means is that actual capture into orbit might not occur until the next day, 7 March. But barring accidents (like the September 2014 cosmic ray event) it should happen soon.
Marshall
 


Re: Speed rel Ceres 50.0 m/s @ 58.4 kkm (nearing capture)

Postby Darby on March 5th, 2015, 3:02 am 

Two problems to solve would be A. energy--an expandable power supply and B. health in 3% of Earth gravity. (genetic modification might be requred)


In-situ power generation is not the deal breaker, because once you harvest the requisite water from the icy mantle, you can use PV to electrolyze it into oxygen & hydrogen, which could then be run through a fuel cell to generate electricity, heat and water on demand, and the resulting water is then recycled in a closed loop (which is what they currently do on the ISS up in LEO). Of the two hurdles you posted, health is the much larger issue, because 0.03G is nowhere near enough gravity to support long term human health, which has already been studied ad nauseum. The moon's 0.16G is 5.5x higher than ceres, and a lot closer to what the human body requires, but it's still not optimal. The much greater proximity to earth would enable the sort of infrastructure needed to have regular transits between the lunar surface and low lunar orbit (using fuel generated in-situ), so that in addition to commuting to and from Earth, people could periodically spend time in a centripitally generated higher gravity habitat in LLO, which could involve a permanent orbital station with a large rotating section. Something like that would be wildly impractical on/around ceres.

Ceres albedo is very dark: 10% I believe. Doesn't that suggest carbonaceous material? What is the chemical composition of the dark crust covering the icy mantel likely to be?


Too soon to tell. Probably best for the time being to assume it's something in the regolith family until it can be scrutinized more closely.
Darby
 


Re: Speed rel Ceres 49.2 m/s @ 59.1 kkm (close to capture)

Postby Marshall on March 5th, 2015, 11:47 am 

Thanks, on the whole your analysis seems on solid ground. Which mammals can stay healthy in low gravity (like 3% or even zero)? I would guess that aquatic mammals like dolphins would not suffer bone loss in low gravity because their body mass is supported by more or less neutral buoyancy. Nor would some of the smaller land mammals, I imagine.
The possibility of genetic modification to adapt to low gravity is interesting. Humans may decide to employ it.
Until that is understood I would say that the problem of health in low gravity has not been adequately studied.

We are close to capture!

Current status as of 5am pacific on 5 March shows speed rel Ceres 49.2 m/s @ distance of 59.06 kkm.
Escape speed at that distance is (2G*943e18 kg/(59060 km))^.5 = 46.2 m/s
So the probe is going 3 meters per second too fast, at this point, to be classified as in orbit.
I expect capture by 7 March, but I'll check later today to see how much the excess speed is whittled down.
Marshall
 


Re: Speed rel Ceres 49.2 m/s @ 59.1 kkm (close to capture)

Postby Marshall on March 5th, 2015, 12:01 pm 

The constellation ORION is very clear in the current status view of Ceres. It helps one get "orionted". The sun must be outside the view frame in the upper left corner direction ----past Orion shoulder star Bellatrix, in effect. The Ceres Sun line deviates from the Dawn Ceres line by about 30 degrees, I would estimate. (To clarify, if Sun were directly behind Ceres, the angle I'm talking about would be zero. But it's not directly behind Ceres, it is up and to the left, past the upper left corner, outside the box.)

The width of the box corresponds to a view angle of 30 degrees. So the sun is up and to the left of Ceres, in the picture, by about the width of the box.
Marshall
 


Re: Speed rel Ceres 48.3 m/s @ 59.7 kkm (close to capture)

Postby Marshall on March 5th, 2015, 12:17 pm 

They just updated current status to 11am pacific (5 March) showing speed rel Ceres 48.3 m/s @ distance of 59.7 kkm.
Escape speed at that distance is
(2G*943e18 kg/(59700 km))^.5 = 45.9 m/s
So the probe is going 2.5 meters per second too fast to be classified as in orbit.
It is still on a flyby trajectory.
Image
Marshall
 


Re: Speed rel Ceres 48.3 m/s @ 59.7 kkm (close to capture)

Postby Darby on March 5th, 2015, 12:31 pm 

If the ion drive is giving them a deceleration delta-v of approx -3 m/s/day, simple arithmetic says they're still on target for their planned capture tomorrow, so it looks like good news.
Darby
 


Re: Speed rel Ceres 48.3 m/s @ 59.7 kkm (close to capture)

Postby Marshall on March 5th, 2015, 12:54 pm 

I'm cautiously optimistic, Darby. But I don't know what the DISTANCE will be tomorrow. It has been increasing roughly 2.5 kkm per day. If we say it is 59.7 now that would make it 62.2 at this time tomorrow
(2G*943e18 kg/(62200 km))^.5 = 45.0

So to have capture by this time tomorrow the speed would have to be under 45.0 m/s

It might be later in the day, tomorrow. Surely by Saturday. :^)
Marshall
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Marshall on March 5th, 2015, 8:41 pm 

there is still a 2 meter per second gap between the probe's speed and what it would need to get down to, to have achieved orbit at this point. right now, if it stopped thrusting it would be on a fly-by trajectory.
this is status as of 1am UT time, 6 March.

I'm thinking maybe sometime late in the day on 6 March. Or maybe 7 March. As the distance increases, escape velocity decreases and that is what you have to get your speed down to.

This paper makes the case for further exploration of Ceres--after the Dawn mission.
http://www.lpi.usra.edu/decadal/sbag/to ... -ceres.pdf
Andrew Rivkin is the lead author. plus some 28 or so others. It's a report to a planning committee:
"We recommend Ceres be considered a candidate for a New Frontiers mission in the 2015-2022 timeframe, with mission architectures to be studied based on results from Dawn and other sources..."

Andrew Rivkin is an astronomer at Johns Hopkins who specializes in studying objects in the asteroid belt, where Ceres is. He is at JHU-APL (the applied physics laboratory at Johns Hopkins)

My guess is Ceres is an attractive world for humans to settle and populate, once some genetic modification makes a bunch of us able to thrive in 3% gravity, GIVEN ONE CRITICAL THING, the availability of nitrogen.

Mars has nitrogen in its atmosphere, only 2.7% by volume but it could be separated out as needed, from the mainly CO2 Mars air.

Other key elements are likely to be available at Ceres, but there is no assurance of nitrogen. It is needed for life as we know it (proteins, amino acids, DNA...) and also incidentally for chemicals like hydrazine, which is N2H4. On the moon any project involving nitrogen would be dependent on some nitrogen material (e.g. ammonia) being IMPORTED FROM EARTH, hydrogen is also scarce on the moon. All this stuff is costly to import because of having to fight gravity.

If Ceres does not have some dissolved ammonia or nitrate salts in its natural environment this could be a stumbling block to its inhabitation by humans (although its water might still be a valuable resource for use elsewhere.)
Marshall
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Darby on March 5th, 2015, 9:03 pm 

There is no simple gene edit that alters human reliance on gravity to any meaningful degree ... it simply doesn't exist. What you're talking about would require wholesale editing of large swaths of our genome, which is far beyond both our current knowledge and technical abilities as well as far across the currently accepted no mans land of medical ethics considerations.

Any researcher or company that lands in the media spotlight for attempting such massive genetic edits will very likely trigger torch wielding mobs of religious pundits and bioethicists alike in fairly short order. It won't be pretty.
Darby
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Marshall on March 5th, 2015, 11:34 pm 

Darby » Thu Mar 05, 2015 6:03 pm wrote:There is no simple gene edit that alters human reliance on gravity to any meaningful degree ... it simply doesn't exist. What you're talking about would require wholesale editing of large swaths of our genome, which is far beyond both our current knowledge and technical abilities as well as far across the currently accepted no mans land of medical ethics considerations.

Any researcher or company that lands in the media spotlight for attempting such massive genetic edits will very likely trigger torch wielding mobs of religious pundits and bioethicists alike in fairly short order. It won't be pretty.


:^)
Sounds like you are presenting your own theories and conjectures as incontrovertible fact, Darby.
Marshall
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Marshall on March 5th, 2015, 11:56 pm 

I would conjecture that calcium loss is a human health problem that millions of people suffer from and it's worth understanding. Elderly people I know have osteoporosis and there are drugs (taken with calcium) that can slow bone loss down. It would be worth scientifically understanding the mechanisms.

I think there are probably several things that cause bone loss INCLUDING failure to put stress on your bones by walking in a gravity field. It would be worth understanding all those causes, and scientifically understanding all the ways to intervene.

I'm skeptical of anyone telling me we understand all this and have researched it "ad nauseam".

At some point EVOLUTION must enter in, because FISH do not stress their bones by walking around in gravity. They live in more of a force neutral environment.

I conjecture that some animals can do much better in weak gravity. And I suspect that LARGE LAND ANIMALS are more likely to need regular stressing of their bones to keep up their bone mass.

I suspect that this has not been thoroughly researched and there is a lot of stuff that is not understood. And because evolution entered in there could be a GENETIC FACTOR that came in at some point in large land animal evolution (by large I include apes). But maybe the small insect eating tree shrews that primates evolved from did not require gravity to prevent bone loss! All sorts of interesting questions here.

There could even be some species of large land animal that don't suffer from weak gravity. I don't know--it's possible (and it's possible I'm wrong).

I think it would be very interesting to find out, and understand the genetic factor.

If you DARBY or anybody has links to research in the GENETIC FACTORS IN animal bone loss, why don't you share them?
Marshall
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Darby on March 6th, 2015, 12:03 am 

Perhaps we can coax faradave to weigh in ?

As an MD id be keen to hear his opinion on the bioethics and state of tech regarding the envisioned idea to leap headlong into eugenics. The last time human engineering was attempted in a big way (re: since gene splicing didnt exist yet the tools of the day were selective breeding of dresirables and sterilization/exterminationof undesirables), it resulted in WW2.This is not mere opinion, this is history. Bioethics is a minefield riddled with historical scars and zealously held differing opinions, and I think it would be a disservice to simply handwave it away.
Last edited by Darby on March 6th, 2015, 12:26 am, edited 1 time in total.
Darby
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Marshall on March 6th, 2015, 12:08 am 

the results of future research are difficult or impossible to predict (science is like that people investigate stuff because they DON'T know the answer and) very smart people are unsure

but human history is maybe not as hard to intuitively foresee.

the health effects of low gravity are RELATED to health problems that million suffer from and will probably be addressed and solved as a BYPRODUCT of general scientific understanding related to widely share conditions (like osteoporosis) kidney stones etc etc. and it seems possible genetic factors might play a role.

and the universe is full of low gravity places to live.

there's a dynamic at work I think. have to play some music with family so have to continue later or tomorrow.
cheers :^)
Marshall
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Darby on March 6th, 2015, 12:27 am 

Crossed posts.
Darby
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby Marshall on March 6th, 2015, 12:56 am 

I think you are confusing gene therapy with "eugenics" and World War II, Darby :^)

The number of people who would need to live a large part of their lives in low gravity would be small at first---not an entire national population. I think there are a number of diseases with a genetic component where specifically genetic intervention might help---small fractions of the population---that is hardly "eugenics".

I agree it might be nice if Faradave would add some medical knowledge.


BTW I've read somewhere that individuals differ in their susceptibility to the ill effects of radiation. Some people are more resistant to cancer-causing radiation than others. There could be a genetic component. I favor massive amounts of shielding which is one reason I'm fascinated by the prospect of humans living in subsurface ice caverns on planets lacking a dense protective atmosphere like Earth's (our deep ocean of air does a great job!)

But a good genetic make-up (radiation resistance-wise) seems like good insurance in addition to a thick roof between you and the planet surface.

We certainly are near the Dawn probe capture moment, I'll go see if current status has changed.
Marshall
 


Re: NEAR CAPTURE! speed 46.5 m/s at 61 kkm (only 1 m/s to go

Postby Marshall on March 6th, 2015, 1:09 am 

Only one more m/s to scrub!
Marshall
 


Re: Speed now 47.4 m/s (v_esc 45.7 m/s @ 60.35 kkm)

Postby doogles on March 6th, 2015, 4:12 am 

Marshall » Thu Mar 05, 2015 11:56 pm wrote:I would conjecture that calcium loss is a human health problem that millions of people suffer from and it's worth understanding. Elderly people I know have osteoporosis and there are drugs (taken with calcium) that can slow bone loss down. It would be worth scientifically understanding the mechanisms.

I think there are probably several things that cause bone loss INCLUDING failure to put stress on your bones by walking in a gravity field. It would be worth understanding all those causes, and scientifically understanding all the ways to intervene.

I'm skeptical of anyone telling me we understand all this and have researched it "ad nauseam".

At some point EVOLUTION must enter in, because FISH do not stress their bones by walking around in gravity. They live in more of a force neutral environment.

I conjecture that some animals can do much better in weak gravity. And I suspect that LARGE LAND ANIMALS are more likely to need regular stressing of their bones to keep up their bone mass.

I suspect that this has not been thoroughly researched and there is a lot of stuff that is not understood. And because evolution entered in there could be a GENETIC FACTOR that came in at some point in large land animal evolution (by large I include apes). But maybe the small insect eating tree shrews that primates evolved from did not require gravity to prevent bone loss! All sorts of interesting questions here.

There could even be some species of large land animal that don't suffer from weak gravity. I don't know--it's possible (and it's possible I'm wrong).

I think it would be very interesting to find out, and understand the genetic factor.

If you DARBY or anybody has links to research in the GENETIC FACTORS IN animal bone loss, why don't you share them?


Re the genetics of bone density, I did a brief Google Scholar search with the keywords GENETICS AND BONE DENSITY. If I was really interested in the field, I would set myself a month of spare time to develop an annotated bibliography based on the following example of references:
http://scholar.google.com.au/scholar?hl ... 5&as_sdtp=

Reduced bone density and osteoporosis associated with a polymorphic Sp1 binding site in the collagen type I α 1 gene
High bone density due to a mutation in LDL-receptor–related protein 5
Genetic variability in adult bone density among inbred strains of mice
Vitamin D–receptor gene polymorphisms and bone density in prepubertal American girls of Mexican descent
Relation of alleles of the collagen type Iα1 gene to bone density and the risk of osteoporotic fractures in postmenopausal women
Six novel missense mutations in the LDL receptor-related protein 5 (LRP5) gene in different conditions with an increased bone density
Genetic influences on bone turnover, bone density and fracture
Genetics of bone mineral density: evidence for a major pleiotropic effect from an intercontinental study
Genetic determinants of bone mass in adult women: a re-evaluation of the twin model and the potential importance of gene interaction on heritability estimates
The genetics of proximal femur geometry, distribution of bone mass and bone mineral density[i]


By simply looking at the headings of these references, I formed the impression that mammalian bone density has enough genetically controlled diversity to adapt to a wide range of variations in gravity – whether that adaptability would apply to 3% of Earth’s gravity is another matter.
As you say Marshall, we don’t know.

I’m intrigued enough to start having looking at the effects of muscle tension on bone density (the relationship to gravity is obvious), and I have some personal anecdotal experience in that field, but brevity suggests a later post if the discussion goes that way.

Just a parting thought on the same subject of adaptability to a gravity of 3% of that of Earth’s. Have you considered that in a gravity of 3%, our osteoporotic citizens may actually be able leap over tall buildings and out-speed a slow bullet?

lol
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Re: NEAR CAPTURE! speed 46.5 m/s at 61 kkm (only 1 m/s to go

Postby Marshall on March 6th, 2015, 10:48 am 

Doogles thanks so much! This is really full of information, and evocative comment!

I have an announcement. Goldstone big antenna just in touch with Dawn, confirms capture

"Confirmed: I am in orbit around #Ceres"
https://twitter.com/NASA_Dawn

orbit.jpeg
Marshall
 
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Re: CAPTURE!

Postby Marshall on March 6th, 2015, 11:22 am 

This NASA announcement
http://www.jpl.nasa.gov/news/news.php?feature=4503
says that capture occurred around 4:39 am pacific time

Now the spacecraft is in orbit, but it is a kind of loose wide-ranging eccentric orbit. So for the next 6 weeks or so it has to work to get closer in and reshape it orbit into one suitable for observation
Marshall
 


Re: CAPTURE!

Postby Marshall on March 6th, 2015, 1:19 pm 

http://www.nasa.gov/press/2015/march/na ... PnYkEI-DVo

This press release has some additional factual detail.
the 4:39am is an extrapolation back from when they actually got word which was more like an hour later.
There was a transmission received around 5:30am pacific.
I think the doppler shift of that transmission gave them speed information, and also of course a report from the probe.
I think in addition to the high gain antenna that the probe has to stop thrusting to use, and point at the earth, the probe has a low-gain antenna which it can use to transmit small amounts of information, without having to interrupt thrusting and change attitude.
Marshall
 


Re: CAPTURE!

Postby Watson on March 6th, 2015, 3:06 pm 

There is a press conference starting shortly.
http://www.nasa.gov/news/media/newsaudi ... Pn3ZvnF-EU
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Re: CAPTURE!

Postby Darby on March 6th, 2015, 5:17 pm 

Marshall: BTW, I hope you dont think I was arguing with you on the bioethics angle, because I havent actually expressed my own personal opinion one way or the other yet**. I just wanted to point out that the vision you put forth would have some pretty profound bioethical considerations, and that the topic has long and storied history of controversy and disagreement that perhaps you havent followed much to date. A cursory glance at all the hoopla over (for example) GMO Crops will give a quick introductory taste of what I'm referring to, and that's just plants, not human beings. It's a big can of worms that wont be resolved anytime soon, and for that reason I think it contributes to the overall set of reasons to view ceres as a non-starter for habitation. That's it in a nutshell.

Ok, back on topic.

------------
** For the record, an enthusiastic yes on gene therapy for the correction of clearly understood diseases or genetic damage rectification, but a very cautious and conflicted "maybe someday when we're a lot smarter and wiser" on eugenics (genetic engineering). The latter field is far too new and is rapidly outpacing our collective wisdom to properly manage it. Color me nervous, because the very soul of science is to explore the unknown and break stuff to see what's inside ... metaphorically speaking, we're big kids who smash stuff and put the fragments in our mouths to see what it tastes like. The test unto breakage is both our path to glory, to understanding, AND our path into danger.
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Re: CAPTURE!

Postby Darby on March 6th, 2015, 5:24 pm 

Regarding:

Perhaps we can coax faradave to weigh in ?


He watered the proverbial fire hydrant on a subsequent post (see below), so he's definitely lurking nearby. ;^)

Faradave liked this post


If he weighs in, perhaps it might warrant a thread split, to avoid dragging this one too far OT ? We've already dragged it into the deep grass several times.
Darby
 


Re: CAPTURE!

Postby Darby on March 6th, 2015, 5:33 pm 

Now the spacecraft is in orbit, but it is a kind of loose wide-ranging eccentric orbit. So for the next 6 weeks or so it has to work to get closer in and reshape it orbit into one suitable for observation


I missed the telecon, but based on your quote it sounds like although they achieved capture ok, the distance it occured at (relative V = zero) was a little off from projections. I'll be keen to see how they refine and revise their predicted orbital insertion diagram from earlier on in this thread, and they'll need at least one more OpNav for that, if not two.
Darby
 


Re: CAPTURE!

Postby Darby on March 6th, 2015, 7:37 pm 

BTW, is anyone else feeling an odd sense of nomenclature deja vu ?

They're calling this the first time we've orbited a Dwarf Planet, even though it just arrived from Vesta (which apparently no longer quite meets the latest and greatest revisions to the definition by the Planetary Society). That was the same occasion they demoted pluto, and Neil DeGrasse Tyson started getting finger painted death threats from disappointed school children.

To quote Maxwell Smart ...

Darby
 


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