Author Topic: NASA Announces New Rover to Close Out Decade of New Missions  (Read 95923 times)

Offline Archibald

  • Senior Member
  • *****
  • Posts: 2611
  • Liked: 500
  • Likes Given: 1096
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #100 on: 12/06/2012 07:04 am »
So the plan is to send a rover taking samples, storing them carefully and then - wait for another mission (robotic or human, who knows) to bring the samples back.
This mean that after some years spent on the surface the rover will meet with a lander (still to be budgeted), and pass it the big bag of samples it will have collected.
Han shot first and Gwynne Shotwell !

Offline Sparky

  • Full Member
  • ***
  • Posts: 378
  • Connecticut
  • Liked: 0
  • Likes Given: 0
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #101 on: 12/06/2012 07:28 am »
So the plan is to send a rover taking samples, storing them carefully and then - wait for another mission (robotic or human, who knows) to bring the samples back.
This mean that after some years spent on the surface the rover will meet with a lander (still to be budgeted), and pass it the big bag of samples it will have collected.


Well, it will be met by a smaller "fetch" rover, the job of which is to retrieve the sample container. It would be rather fruitless if the caching rover were to fail before the return mission arrives. But yes.

Online Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 15289
  • Liked: 7827
  • Likes Given: 2
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #102 on: 12/06/2012 11:56 am »
I get the impression that some of you guys read one post and then ask the same questions that have been answered multiple times before in earlier posts.

Well some of us don't have the time to be on this forum often or long enough to read all the posts, perhaps if you would be so kind as to quote/link the answers to those questions, can't seem to find anything via search.
 

Just read earlier in the thread so that you don't ask a question that has been answered three times before and look like a newbie.

Online Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 15289
  • Liked: 7827
  • Likes Given: 2
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #103 on: 12/06/2012 12:01 pm »
So the plan is to send a rover taking samples, storing them carefully and then - wait for another mission (robotic or human, who knows) to bring the samples back.
This mean that after some years spent on the surface the rover will meet with a lander (still to be budgeted), and pass it the big bag of samples it will have collected.


Well, it will be met by a smaller "fetch" rover, the job of which is to retrieve the sample container. It would be rather fruitless if the caching rover were to fail before the return mission arrives. But yes.

Yes. If you want to get a sense of the overall architecture, go to this site:

http://www7.nationalacademies.org/ssb/SSB_059331.htm

Download the mission studies for MAX-C, Mars Lander and Mars Orbiter. Those are the three components. Of the three, the lander, which includes the ascent vehicle, is the most difficult. We know how to do rovers and orbiters and return vehicles (and even automated rendezvous). The ascent vehicle is tough because it has to survive the Mars thermal cycling (cold and colder). It would have a small "retrieval rover" for getting the sample canister onboard.

Offline Archibald

  • Senior Member
  • *****
  • Posts: 2611
  • Liked: 500
  • Likes Given: 1096
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #104 on: 12/06/2012 12:28 pm »
So we are talking about a rover meeting another rover to retrieve the canister and place it aboard the return ship.
Then what happens to the fetch rover ? abandoned on Mars ?
Can't help thinking about Wall-E and its fellow robots - Eva, Mo... ;D 
That will be one hell of a mission. I want to see that in my lifetime.

If only humans were not so "costly" to land on Mars, a suited astronaut might be as efficient as the rovers to collect the canister and bring it aboard...
« Last Edit: 12/06/2012 12:30 pm by Archibald »
Han shot first and Gwynne Shotwell !

Offline JohnFornaro

  • Not an expert
  • Senior Member
  • *****
  • Posts: 10974
  • Delta-t is an important metric.
  • Planet Eaarth
    • Design / Program Associates
  • Liked: 1257
  • Likes Given: 724
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #105 on: 12/06/2012 12:58 pm »
I get the impression that some of you guys read one post and then ask the same questions that have been answered multiple times before in earlier posts.

Well some of us don't have the time to be on this forum often or long enough to read all the posts, perhaps if you would be so kind as to quote/link the answers to those questions, can't seem to find anything via search.

Search function here doesn't work all that well.  On short threads, you can pick "All", then use the Inet Explorer search function for an applicable term or short phrase.  Say, "Delta-v"; "delta vee"; vary the spelling sometimes.  On long threads, you can use the "print" function, which will display the text of the entire thread; again the Inet Explorer search function works well for finding some things, particularly posters.  The print function doesn't fully implement the nested quote function, but it sorta works.

So there's that.

Nothing can be done about someone not having enough time to read.  You have to make that time yourself.  Plus, it's very time consuming for somebody else to apply "research" methods, and supply quotes across threads to bring "you" up to date.  The common phrase is "do your own homework".
Sometimes I just flat out don't get it.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21451
  • Likes Given: 428
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #106 on: 12/06/2012 01:05 pm »

1.  Legit question:  How hard is it to modify the cruise stage of the EDL sequence to be able to also (aero)brake into orbit after detaching the decent stage, to then remain in orbit as a comsat?

2.  Also:  What's the delta v to get to Mars GSO above the rover landing site, so as to remain always in view?

3.  I'm thinking that a manned mission base requirement could well be a GSO relay, so that maintaining comms is basically no more than a home cable dish.  Any need to demonstrate the technology?  It'd be fun...


1.  Very hard. 
A.  It is going too low to aero brake and it would still take a lot of prop.
b.  The cruise stage has no guidance or computer, its thrusters are set up for a spinning vehicle with the entry vehicle still attached, its solar arrays are sized to just power some pumps and star tracker, and where would the comm gear and antenna go?

2.  Way too much to add on to the above

3.  The issue is justifying the dedicated mission

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21451
  • Likes Given: 428
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #107 on: 12/06/2012 01:06 pm »

I think that it a good idea,

It is a bad idea

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21451
  • Likes Given: 428
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #108 on: 12/06/2012 01:07 pm »
I get the impression that some of you guys read one post and then ask the same questions that have been answered multiple times before in earlier posts.

Well some of us don't have the time to be on this forum often or long enough to read all the posts, perhaps if you would be so kind as to quote/link the answers to those questions, can't seem to find anything via search.
 

Not our job.

Offline Norm38

  • Full Member
  • ****
  • Posts: 1696
  • Liked: 1272
  • Likes Given: 2317
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #109 on: 12/06/2012 01:46 pm »
Thanks Jim, figured it was a long shot.

Online Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 15289
  • Liked: 7827
  • Likes Given: 2
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #110 on: 12/06/2012 02:06 pm »
Another possibility is the "fetch rover" going to retrieve a canister with samples, rather than going up to the sample collecting rover.

The canister itself is an interesting device. Although it has no moving parts, it is fairly complex. It has to be designed to seal the samples securely under various thermal environments, even in the event of Earth impact.

Offline FOXP2

  • Member
  • Posts: 81
  • Liked: 0
  • Likes Given: 0
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #111 on: 12/06/2012 05:26 pm »

I think that it a good idea,

It is a bad idea

How not to be a dick, jim, lesson #1: "Say "that a good idea, but..." and then state show stopping detriments without stating them as such.  Instead of saying "that a bad idea."

Observe: "I think that it a good idea, but it would add a lot of mass."

Now if you really think flying a lander and orbiter together is a "bad idea" take that up with the designers of Viking, Mars Express, ExoMars, etc.     

Quote
Not our job.

I doubt its your job to be on this forum either. In short if your going to waste time chating on an internet forum, I see no reason to not be constructive and helpful... well unless being the opposite is fundamental to your personality. 

I get the impression that some of you guys read one post and then ask the same questions that have been answered multiple times before in earlier posts.

Well some of us don't have the time to be on this forum often or long enough to read all the posts, perhaps if you would be so kind as to quote/link the answers to those questions, can't seem to find anything via search.
 

Just read earlier in the thread so that you don't ask a question that has been answered three times before and look like a newbie.

I did, I can't find answers to
-What is the max max range of Electra?
-What is Electa bit rate at that max range?
-Could ASRG be used on this upcoming rover?

As for complaints that I should look it up on my own, yes I should, and did, but didn't find it on this forum:

Electra can detect a carrier signal at 110,000 km and can communicate at 1 "ksps" at 35,000 km [1]. That would mean at least 1 kbps (I assume 2 kbps at 2 bits per sample) at that distance. Simulations show 64 kbps at 6000 km is possible with standard Electra design [2]. Back-of-napkin calculate MSL averages between 208-521 kbps with existing orbiter passes that have slant ranges between 250 km to ~1000 km and fly over times averaging 8 minutes.[3]

So MAVEN should be able to communicate with a rover even at apogee at ~64 kbps to perhaps as high as 2 Mbps at pregee, right over the rover. MAVEN orbital period will be 4.5 hours long, so yes it could hang over a rover for more then 2 hours, that would be enough time to download nearly half a Gb at 64kbps, or roughly 2-5 times existing orbiter overflight performance. Unfortunately such perfect overflights would only happen rarely as MAVEN will precess in latitude as well as flyover fewer times a sol, but its average overflight time should be considerably longer then other orbiters. The question thus becomes will its reduced average bit rate be made up for by longer average and seasonally varying overflight time? There certainly would be times during a martian year where due to latitude a rover rarely if every has view of MAVEN at apogee, only of it at pregee, overflights of which would be shorter then existing orbiters and happen less then half as often due to its longer period.   
       
As for arguments that a rover could go it alone with direct to earth that would be 32 kbps at earth mars conjunction to just 0.5 kbps (500 bits) near opposition, provisional average of 3.5 kbps![3] So the orbiters are critical to lander performance: they increase data return rates from the surface by ~100 times. Right now there are 2 NASA orbiters one working full time as a relaying, and one ESA orbiter which is used rarely if ever. By 2020 there will likely only be one NASA orbiter which will be on its 7th year and a ESA mission on its 2-4th year. 

[1]http://books.google.com/books?id=4Q9BuPCKeDkC&pg=PA160&lpg=PA160&dq=electra+transceiver+110,000&source=bl&ots=EFfslyQ2Y_&sig=UKEhwt3-k0NE4YK7bo2bsalvbyQ&hl=en&sa=X&ei=1ErAULW4EcnzqAGF74Aw&ved=0CDAQ6AEwAQ#v=onepage&q=electra%20transceiver%20110%2C000&f=false
[2] http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/7832/1/03-2150.pdf
[3] http://mars.jpl.nasa.gov/msl/mission/communicationwithearth/data/

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21451
  • Likes Given: 428
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #112 on: 12/06/2012 05:31 pm »

I think that it a good idea,

It is a bad idea

How not to be a dick, jim, lesson #1: "Say "that a good idea, but..." and then state show stopping detriments without stating them as such.  Instead of saying "that a bad idea."

Observe: "I think that it a good idea, but it would add a lot of mass."

Now if you really think flying a lander and orbiter together is a "bad idea" take that up with the designers of Viking, Mars Express, ExoMars, etc.     

Quote
Not our job.

I doubt its your job to be on this forum either. In short if your going to waste time chating on an internet forum, I see no reason to not be constructive and helpful... well unless being the opposite is fundamental to your personality. 


How not to be a dick is not to ask to be spoon fed data.  I am not going to waste time helping someone who is lazy and makes unsubstantiated comments.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21451
  • Likes Given: 428
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #113 on: 12/06/2012 05:35 pm »

Now if you really think flying a lander and orbiter together is a "bad idea" take that up with the designers of Viking, Mars Express, ExoMars, etc.     


Mars express is not a relevant example since Beagle was a secondary.

No US lander since Viking, Pathfinder, MPL, MER, Phoenix, MSL haven't flown with orbiters and that goes with future ones too.
« Last Edit: 12/06/2012 05:36 pm by Jim »

Offline Khadgars

  • Full Member
  • ****
  • Posts: 1750
  • Orange County, California
  • Liked: 1132
  • Likes Given: 3156
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #114 on: 12/06/2012 05:43 pm »
Quote
I think that it a good idea,


It is a bad idea


How not to be a dick, jim, lesson #1: "Say "that a good idea, but..." and then state show stopping detriments without stating them as such.  Instead of saying "that a bad idea."

Jim is one of the more knowledgeable people on this forum, he grows on you after a while  :P
Evil triumphs when good men do nothing - Thomas Jefferson

Offline Kaputnik

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 3079
  • Liked: 722
  • Likes Given: 821
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #115 on: 12/06/2012 08:45 pm »
Just to add a, hopefully, constructive twist to the cruise bus -> GSO orbiter idea (actually, the term wouldn't be geostationary at all, since that term is reserved for Earth).

The cruise bus will, by default, intersect the atmosphere deeply enough to de-orbit (if it didn't, then neither would the entry vehicle). So the proposal would need a burn to get it clear of the atmosphere- I'm not sure how feasible that is, and I would guess that it requires an earlier release of the entry vehicle, which has obvious implications.
Having cleared the atmosphere, the bus/orbiter could brake into a very highly elliptical orbit. Another burn would be required at the high point of the orbit to circularise. That will be a very, very big burn indeed.

Due to the delta-v involved, I don't think we'll see a stationary satellite around Mars, at least not until we have electric propulsion on the go and it can spiral into position.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #116 on: 12/06/2012 08:47 pm »
Is someone going to talk about repurposing the ejected off-set weights, too?  ::)
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 15289
  • Liked: 7827
  • Likes Given: 2
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #117 on: 12/06/2012 08:52 pm »
I did, I can't find answers to
-What is the max max range of Electra?
-What is Electa bit rate at that max range?
-Could ASRG be used on this upcoming rover?

ASRG will NOT be used on this rover. Mentioned earlier in the thread. I could explain a million reasons why, but the simplest one is that NASA will not put ASRG on a $1.5 billion mission until it is flight tested first on a cheaper mission. Another reason is that you don't want to "clone" Curiosity and then put an entirely different power system on it. That would add risk to the design.

Relay is not an issue. I don't know why you guys seem to be obsessed with it, but once MAVEN's primary mission is over it's going to be used for relay until it falls out of the sky. And ESA's going to have an orbiter too. There will be plenty of comm. I work with Mars scientists and they're not worried about the relay issue. Not an issue. There are better windmills to tilt at.
« Last Edit: 12/06/2012 08:53 pm by Blackstar »

Offline Norm38

  • Full Member
  • ****
  • Posts: 1696
  • Liked: 1272
  • Likes Given: 2317
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #118 on: 12/06/2012 08:59 pm »
I thought the cruise stage had it's own RCS, radio, etc.  Forgot they were all on decent.  Was really just curious about how much extra mass it would be.  A lot.

I wish I knew orbital mechanics.  Speaking just of delta v, shouldn't it be possible for a craft designed to do so, to (aero)brake just enough to be captured by Mars in a high eliptical orbit that can then transition to MSO, for some delta-v savings?

Or do you really have to capture into a low orbit and then boost back out?
« Last Edit: 12/06/2012 09:00 pm by Norm38 »

Offline Kaputnik

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 3079
  • Liked: 722
  • Likes Given: 821
Re: NASA Announces New Rover to Close Out Decade of New Missions
« Reply #119 on: 12/06/2012 09:06 pm »
I thought the cruise stage had it's own RCS, radio, etc.  Forgot they were all on decent.  Was really just curious about how much extra mass it would be.  A lot.

I wish I knew orbital mechanics.  Speaking just of delta v, shouldn't it be possible for a craft designed to do so, to (aero)brake just enough to be captured by Mars in a high eliptical orbit that can then transition to MSO, for some delta-v savings?

Or do you really have to capture into a low orbit and then boost back out?

There are essentially two ways of achieving 'Areostationary' orbit.
One is to approach the planet on a wide flyby trajectory, aiming for a 17,000km altitude. Upon closest approach, perform a burn to enter ASO directly.
The second way is to make a more conventional approach in the region of 120km. Again, make the braking burn at closest approach. This is actually a much more efficient way of entering orbit due to the 'Oberth effect'. However it places you in an orbit with a low point of 120km. The high point depends on how long you burned your engines for. So, assuming you achieved a 120x17,000km orbit, you will need a second burn (condcuted at the high point) to circularise. That will take a lot of propellant.

I admit I don't know enough about orbital mechanics to which of these methods is more efficient. However, only the second one has any applicability to a bus/orbiter approach.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1