Author Topic: Gerstenmaier expands on recently announced asteroid mission  (Read 114548 times)

Offline JohnFornaro

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #40 on: 04/26/2013 07:28 PM »
If all we get to choose from is an unknown rock...

For the umpteenth time:

Arkyds

In Fornaro's world we would drag back a rock we know absolutely nothing about.

But PR's plan is to drag back a rock after extensive reconnaissance and prospecting. And NASA has expressed a desire to work with PR and DSI.

This is not in my world at all.

You are wrong again, and you do worse than willingly and knowingly mischaracterize my position. 

As you know, nobody will know for many years which rock will be the candidate.  We taxpayers are asked to trust you and the people you agree with, that you all will know it when you find it.

Left unaddressed by you are these things:

1. Whether or not the rock has any utility, beyond the theoretical.

2. Whether 100 tons of water could be cracked in zero gee, in an HLO, and why hasn't this non-exsistant technology been acoounted for in mission planning to date.

3. Whether the mission is an SEP demonstration mission, or an asteroid capture mission.  Gerst has taken asteroid capture off of the table.

4. Therefore, whether or not "nothing" in HLO has any utility.

5. If they change their plan again, and commit to capturing an asteroid, whether or not the maiden manned BEO mission is risk free enough to attempt 8 hours of EVA.

6. Whether or not eight hours of "exploration" is worth the tens of billions of dollars over more than a decade, to actually attempt asteroid capture.

7. Whether or not the mission is properly scoped in the first place, according to the Keck paper.

8. Whether or not there will be funding for this mission, the development of the necessary technology to the levels demanded by Keck, the related costs of SLS, and of the launch itself.

9. Etc. 
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #41 on: 04/26/2013 07:29 PM »
If the Chelyabinsk meteor had entered at a different angle it would have detonated with its ~50X Nagasaki power at ground level, not 35km up.  Even the expense of this mission is justified to be able to prevent the destruction of a city in the future.

Cite on either of those claims?
Sometimes I just flat out don't get it.

Offline rcoppola

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #42 on: 04/26/2013 08:10 PM »
Why not just test the propulsion system on an unmanned, relatively inexpensive program instead (if it's a "must have" for Mars)?
Exactly. There is no need to invent another "Mission" just to test SEP.


The SEP will be on the unmanned portion of the mission- the robotic asteroid fetching leg. 

Having the proven capability to find, travel too, grab, and re-direct something of this size (the Chelyabinsk meteor class is only a bit larger) is a great start to planetary protection, and a worthy goal in and of itself, and an excellent use of a 40 kW SEP module, and a good reason to do the test exactly this way. 

If the Chelyabinsk meteor had entered at a different angle it would have detonated with its ~50X Nagasaki power at ground level, not 35km up.  Even the expense of this mission is justified to be able to prevent the destruction of a city in the future.

Addendum: Development of the kind of advanced space infrastructure required to make everyone/anyone in the human spaceflight fan camp happy requires money.  The biggest historical driver of spending on space was to counter perceived geopolitical threats.  The cold war space race was great for space, and the specter of asteroid threats can fill a similar role.  Embrace this mission.
I fully support the mapping and subsequent detection of potential earthbound meteors/asteroids.

And if the powers that be would like to open an Office Of Planetary Protection, staff it, write some plans for plans, get funded and execute a few missions to test out the capabilities as currently outlined, then great.

Otherwise, we've already embraced a mission. It's called Mars. And we don't need to capture rocks to test out the tech with which to get there. It's a nice to have, not a need to have. And with our current funding levels, we should only be looking at need to have.

 
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Offline aero

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #43 on: 04/26/2013 08:22 PM »
Quote
Otherwise, we've already embraced a mission. It's called Mars. And we don't need to capture rocks to test out the tech with which to get there. It's a nice to have, not a need to have. And with our current funding levels, we should only be looking at need to have.

I disagree. Thinking like that got us the shuttle and the ISS, at the expense of three quarters (my estimate) of the real exploration programs. And now what do we have? No shuttle, it was worn out building the ISS, and the ISS will soon be decommissioned leaving us with nothing to show for 50 years of spacefilght, except for some commercial satellites.

This history has just proven again what any school child can tell you; its a bad idea to put all the eggs in one basket.
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Offline LegendCJS

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #44 on: 04/26/2013 08:30 PM »
If the Chelyabinsk meteor had entered at a different angle it would have detonated with its ~50X Nagasaki power at ground level, not 35km up.  Even the expense of this mission is justified to be able to prevent the destruction of a city in the future.

Cite on either of those claims?
Ok. You got me.  I made up numbers to support my argument without actually looking them up.  But they were based on my memories of many references about the event, and they don't change anything and aren't even that wrong. Latest estimates: explosion 35-23km up, 20-30X Hiroshima bomb force, shallow 16 deg angle of entry.  It streaked for ~32 seconds from atmospheric entry to detonation.  Latest size estimates are upper bounded by 20-22m diameter, lower bounded by 17m.

One scientists expert says that, because of the velocity of the body at the time of the explosion, the destructive effect is projected along the velocity vector, and since this vector was 16 deg from horizontal, its impact on the ground was much reduced.  He said that for the same explosion at the same altitude damage on the ground may have been an order of magnitude worse if the velocity vector was 16 deg from vertical instead.

And it is a classroom/textbook geophysics result that the entering meteors detonate deeper in the atmosphere the steeper the angle of entry, compounding the worsening effect mentioned above based on the velocity vector projection of the blast effects.

Citations:
Latest estimates of the numbers on the event: just google and pick your event summary article from your favorite popular science outlet of choice.

Steeper entry angle = deeper detonation: go to a library and find a geophysics textbook

Velocity vector projection of blast effects: the statements of Peter Brown of the University of Western Ontario, as summarized in the April 15th article on thespacereview by Jeff Foust titled "Piecing together the Chelyabinsk event"

The only matter of opinion in my post is if the capability to prevent this in the future is worth the expense.  For that claim I can't provide a citation beyond saying that many cities have a yearly contribution to the GDP of their countries much larger than the total sum of money needed to execute this asteroid capture mission.
« Last Edit: 04/26/2013 08:32 PM by LegendCJS »
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline renclod

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #45 on: 04/26/2013 09:31 PM »
>>> Mr. Gerstenmaier mentioned NASA teams “were looking at potentially using the launch and entry suits with modified EMG (electromyographic sensors) to provide an EVA capability. <<<

Or maybe modified TMG, thermal meteoroid garment ?

>>> Mr. Gerstenmaier added that the Orion EVA capability “was a design case for Orion, but not many people thought that we were going to do it fairly early in the (exploration roadmap) sequence.” <<<

CxP/Orion EVA suit design was by umbilicals, IIRC. Did that changed ?

IIRC Orion's capability of supporting EVA was placed on back burner some time ago - am I wrong ?

=========
Thanks for the article, good stuff !

« Last Edit: 04/26/2013 09:36 PM by renclod »

Offline Chris Bergin


IIRC Orion's capability of supporting EVA was placed on back burner some time ago - am I wrong ?


Yeah, and it wasn't "from the Orion" in some cases. From an old article using L2 content, I remember one concept involved an airlock module (with a RMS) between an Orion and a Centaur! (Not that this is at all going to be the deal now).
« Last Edit: 04/27/2013 12:09 AM by Chris Bergin »

Offline JohnFornaro

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #47 on: 04/27/2013 01:26 AM »
If the Chelyabinsk meteor had entered at a different angle it would have detonated with its ~50X Nagasaki power at ground level, not 35km up.  Even the expense of this mission is justified to be able to prevent the destruction of a city in the future.

Cite on either of those claims?

1) Ok. You got me.  I made up numbers to support my argument without actually looking them up.  ...

2) Steeper entry angle = deeper detonation: go to a library and find a geophysics textbook

3) Velocity vector projection of blast effects: the statements of Peter Brown of the University of Western Ontario, as summarized in the April 15th article on thespacereview by Jeff Foust titled "Piecing together the Chelyabinsk event"

4) The only matter of opinion in my post is if the capability to prevent this in the future is worth the expense.  For that claim I can't provide a citation beyond saying that many cities have a yearly contribution to the GDP of their countries much larger than the total sum of money needed to execute this asteroid capture mission.

1) Believe what I say or not, I'm not into "gotchas".  Which is entirely different from accepting assertions without substantiation.

2) I'm quite aware of this general fact.

3) Well, I admit that the guy said several things of interest.  Yes, he "estimated" thusly: "Had the Chelyabinsk meteor come in at a steeper angle -- say, 16 degrees to the vertical -- the shock wave effects would have been an order of magnitude stronger, Boslough estimated."

When folks around here ask for a cite, this isn't exactly what they accept.  But you left out another opinion:

Quote
"We’re greatly exaggerating the danger," said David Morrison of NASA and the SETI Institute, noting that many people were killed in shootings or automobile accidents just during the time of the session, while Chelyabinsk killed no one. "It would greatly distort our true interest in surveying for near Earth objects in the 100, 200, 300 meter range that are the real danger if we try to divert our interest to worrying about a once-in-a century event that didn’t kill anyone."

Which leads to thing #4:

4) The hype about planetary protection is pretty much a chicken little argument to drum up funding for a specialized jobs program.  Perfectly legal, mind you.  Doesn't mean that I should "automatically" approve of this expenditure of my money.

You realize that there is not that much "excitement" or "inspiration" about this proposed mission in the larger scientific community, and that my voice is a small one in that much larger choir.  I suppose you could revert to Hop_David's strategy, personally denigrating this messenger, in order to garner support for this poorly prioritized expenditure of scarce funds for a questionable goal which will not be sought after all that much, according to Mr. Gerstenmaier's latest comments.

I mentioned 8 of my specific objections to this mission just above.
Sometimes I just flat out don't get it.

Offline Lar

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #48 on: 04/27/2013 06:07 AM »
Addendum: Development of the kind of advanced space infrastructure required to make everyone/anyone in the human spaceflight fan camp happy requires money.  The biggest historical driver of spending on space was to counter perceived geopolitical threats.  The cold war space race was great for space, and the specter of asteroid threats can fill a similar role.  Embrace this mission.

Good point. Problem is, that there is a lot of time for the mundanes to realize the Chicken Little aspect of claiming there's a problem. If there are skeptics in the space community, just wait... the mundane press will find and exploit the skepticism. Spending money on this interferes with bread and circuses.
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Offline Robert Thompson

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #49 on: 04/27/2013 10:09 AM »
http://www.spacedaily.com/reports/Astronomer_Asteroid_could_make_close_flyby_in_2026_999.html
Says close approach of a Chelyabinsk at 5300 miles (8500 km)

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2013%20GM3;orb=0;cov=0;log=0;cad=1#cad
Puts it (as of today) between 46000 km near and 274000 km nominal.

Offline MP99

http://www.spacedaily.com/reports/Astronomer_Asteroid_could_make_close_flyby_in_2026_999.html
Says close approach of a Chelyabinsk at 5300 miles (8500 km)

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2013%20GM3;orb=0;cov=0;log=0;cad=1#cad
Puts it (as of today) between 46000 km near and 274000 km nominal.

Is that unusual - 0.008 AU flyby of Venus (1977), and 0.002 AU flyby of Earth (2026)?

cheers, Martin

Offline JohnFornaro

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #51 on: 04/27/2013 12:28 PM »
http://www.spacedaily.com/reports/Astronomer_Asteroid_could_make_close_flyby_in_2026_999.html
Says close approach of a Chelyabinsk at 5300 miles (8500 km)

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2013%20GM3;orb=0;cov=0;log=0;cad=1#cad
Puts it (as of today) between 46000 km near and 274000 km nominal.

Is that unusual - 0.008 AU flyby of Venus (1977), and 0.002 AU flyby of Earth (2026)?

From a propaganda standpoint, .002 AU sounds a lot smaller than 46,000 km.  It will only miss us by "that much".
Sometimes I just flat out don't get it.

Offline yg1968

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #52 on: 04/27/2013 12:59 PM »
>>> Mr. Gerstenmaier mentioned NASA teams “were looking at potentially using the launch and entry suits with modified EMG (electromyographic sensors) to provide an EVA capability. <<<

Or maybe modified TMG, thermal meteoroid garment ?

=========
Thanks for the article, good stuff !


Corrected. Thanks!

Offline Hop_David

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #53 on: 04/27/2013 06:07 PM »
I suppose you could revert to Hop_David's strategy, personally denigrating this messenger,

You had said NASA has a policy against re-use. I had given counter-examples and asked you for a cite.

After forcing me to wade through several walls of text, you finally admitted this was a policy you made up.

For me time is a limited commodity and you have wasted it. You deserve to be denigrated.

Offline Hop_David

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #54 on: 04/27/2013 06:35 PM »
When folks around here ask for a cite, this isn't exactly what they accept.

You're in no position to be pointing fingers here. See my post just above.

Here's a link to the Space Review article: Piecing together the Chelyabinsk event.

Quote
Chelyabinsk lucked out, though, since the track of the meteor was relatively shallow: about 16 degrees. Had the Chelyabinsk meteor come in at a steeper angle—say, 16 degrees to the vertical—the shock wave effects would have been an order of magnitude stronger, Boslough estimated. “The damage on the ground at ground zero would have been much more serious,” he said. “The people in Chelyabinsk and surrounding villages were lucky that this came in at such a shallow angle.”

Personally I regard Mark Boslough as credible. He is correct, the event could have easily been much worse.

Chelyabinsk pinged the radar screens of many folks who ordinarily never even think of space policy. Planetary defense is gaining popular support and rightfully so.


Offline JohnFornaro

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #55 on: 04/28/2013 01:51 PM »
NASA has a policy against re-use.  This is why Jim keeps pointing out that the USG has no need to re-use space hardware.  Hop_David continues to struggle with differentiating opinion from fact, but he has no problems in quoting various cites which only support his opinions.  Somehow, he has lost the ability to use the PageDn key, and claims that he has been "forced" to read opinions that are not his own.

He acknowledges being "forced" to read about the technical issues I raise objecting to the asteroid heist, but he will assiduously not address them.  At all.  Even while he reads the article that he presents as his authoritative "cite".

The "danger" of an asteroid strike is official hype made by proponents of this unfortunately prioritized mission.

Quote
"We’re greatly exaggerating the danger," said David Morrison of NASA and the SETI Institute...

If a large, previously unseen asteroid of about 17 m in diameter lands in the middle of Meteor Crater in Arizona tomorrow, having entered the atmo at a ninety degree angle, it would serve as an existential example of the technical arguments I have raised regarding the implausible practicality of the heist.

If it could be hypothesized that I could have a drink with Gerst after work on Friday, off the record, I could test my hypothesis that he has been instructed to expand on the recently announced asteroid mission, as reported in the OP.

I'll buy.
Sometimes I just flat out don't get it.

Offline Hop_David

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #56 on: 04/28/2013 05:25 PM »
NASA has a policy against re-use.  This is why Jim keeps pointing out that the USG has no need to re-use space hardware.

Jim  is correct. In most cases there is no reason to re-use hardware.

For decades NASA had a partially re-usable vehicle - the space shuttle. But it wasn't economic. Single use expendable vehicles are cheaper to get stuff to orbit.

Is this due to NASA policy? No. It has more to do with the laws of physics. Tsiolkovsky's rocket equation. Extreme temperatures on re-entry. etc.

Occasionally there are missions whose hardware is still able at the end of the mission. If it's economic NASA can and will re-use hardware. Some examples:

Themis which was re-used in the Artemis mission.
Deep Space 1 was re-used to fly by a comet
Deep Impact was re-used in Epoxi

All of the above unexpectely long lived hardware use ion engines The Keck proposal calls for Hall Thrusters. It's not a given the Keck hardware would be worn out and unusable after the first retrieval.

Nor is it a given that economics dictates chemical rockets must always be expendable. Astronaut Don Pettit notes extra-terrestrial propellant could break the tyranny of the rocket equation.

There are two potential sources of propellant that could break the tyranny of the rocket equation: 1) lunar cold traps, 2) water rich NEAs.

You argue that savings from in situ propellent can't be realized for water rich NEAs because of a NASA policy against re-use. But it still hasn't dawned on you that this policy would be just as damaging to getting propellent from lunar cold traps. Your imaginary policy would kill your favorite hobby horse as well as asteroid in situ resources.

Further, it's unlikely NASA would be they only entity involved. They've expressed a desire to work with PR and DSI. Do these two entities also have a policy against re-use?

Somehow, he has lost the ability to use the PageDn key, and claims that he has been "forced" to read opinions that are not his own.

I don't mind reading opinions that aren't my own.

I do mind wading through walls of text when the message could be given in one sentence. Brevity, please.

Just admit your NASA policy against re-use is bollocks and move on.

Quote
"We’re greatly exaggerating the danger," said David Morrison of NASA and the SETI Institute...

You clipped part of Morrison's quote:

Quote
It would greatly distort our true interest in surveying for near Earth objects in the 100, 200, 300 meter range that are the real danger if we try to divert our interest to worrying about a once-in-a century event that didn’t kill anyone.

Chelyabinsk and Tunguska sized rocks merely have the potential to destroy cities. He regards them as a distraction from more devastating rocks.

But the potential city killers are much more common than potential nation killers. We should still find the smaller rocks and prepare to divert them.

It's like saying ordinary rain storms are much less devastating than tornadoes. Therefore patching my roof against the more common occurance is a needless distraction when I should be preparing my house to endure rare tornadoes.

« Last Edit: 04/28/2013 05:28 PM by Hop_David »

Offline JohnFornaro

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #57 on: 04/28/2013 05:41 PM »
PageDn.
Sometimes I just flat out don't get it.

Offline phred

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #58 on: 04/28/2013 06:04 PM »
I hope they don't fit this architecture model for science. Let the science float. Let the science quality of the target be the dead last concern. Photo ops can be re-captioned to enhance or make crucial the science achievements. Prioritize making the rockets go, on time, as soon as the least acceptable target allows, and getting boots beyond LEO. Behind the scenes, behind the photo ops, robots can cover the actual science and sample return from many places no boots will live.

Could be they won't be able to be choosey about the asteroid.  And it seems to me that the survey resources required to find a good candidate rock will add so much to Solar System science as to qualify as an adequate scientific justification all by itself.

The Gerstenmeier quote where he says "the mission also builds NASAs toolbox for the ultimate goal, Mars."  I'll bet that's a big motivation in this.  A 40 kW solar-electric unit is a nice thing to have in the garage.

Thanks YG for a cool cool article.

Offline deltaV

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Re: Gerstenmaier expands on recently announced asteroid mission
« Reply #59 on: 04/28/2013 06:10 PM »
Would it make sense to design a 100 kW SEP tug with a 50 kW configuration? The latter would be for the asteroid retrieval mission and the former could be used for LEO<->EML shuttling. Basically plan the upgrade path in advance even if a little efficiency is lost.

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