IPB

Welcome Guest ( Log In | Register )

2 Pages V   1 2 >  
Reply to this topicStart new topic
"Search for life on Mars is frozen", Interesting article by Colin Pillinger.
sci44
post Nov 19 2008, 02:04 PM
Post #1


Junior Member
**

Group: Members
Posts: 63
Joined: 18-November 08
Member No.: 4490



The Telegraph has this interesting new piece written by Colin Pillinger.
(I am posting to Beagle-2 thread, although it also covers Phoenix, ExoMars and Mars exploration in general.) You may remember this piece of his in the Guardian back in May.
It was always a great shame that no one can find the relatively small sum needed to send another Beagle-3 - it would be a great way to provide a continuing back-up Mars surface mission should (god forbid) there is a hitch with MSL. How practical would it be to add to a planned mission like MAVEN? How much more, in terms of an attatched delivery craft/system, etc, would be needed if it was sent on one of the new cheaper launchers, like Falcon-1/9? Beagle 2 weighed 69kg at launch and Falcon-1 delivers 670kg to LEO - which I would doubt is enough for a cruise stage plus fuel..
Go to the top of the page
 
+Quote Post
ugordan
post Nov 19 2008, 02:26 PM
Post #2


Senior Member
****

Group: Members
Posts: 3648
Joined: 1-October 05
From: Croatia
Member No.: 523



The most recent figures say Falcon 1 delivers 420 kg to 185 km LEO, while the stretched Falcon 1e, available from 2010 is supposed to be able to lift 1010 kg. Without a third, kick-stage, Falcon 1e cannot deliver anything to escape velocity. Falcon 9 on the other hand is expected to be able to boost 1200 kg to a Mars transfer trajectory directly.

Why would you want to send another Beagle 2? It was obviously not a robust enough design to live through EDL, would you like to see the failure happen again?


--------------------
Go to the top of the page
 
+Quote Post
sci44
post Nov 19 2008, 02:44 PM
Post #3


Junior Member
**

Group: Members
Posts: 63
Joined: 18-November 08
Member No.: 4490



QUOTE (ugordan @ Nov 19 2008, 02:26 PM) *
Why would you want to send another Beagle 2? It was obviously not a robust enough design to live through EDL, would you like to see the failure happen again?


Because it had a very good science package for the weight/price. Of course, without descent comms we will never know what happened for sure - it is possible it was not a design failure, just bad luck with the landing site. I think the big problem at the time was the impossibly tight schedule for implementation - not enough time to retest everything before final delivery. There was also a late reduction from the ESA in allowed probe weight - its amazing to get anything for that specification. A second bite would provide the team with a chance to refine the design - I dont know whether a descent comms package could be added with a little more weight to play with.
Go to the top of the page
 
+Quote Post
ugordan
post Nov 19 2008, 02:52 PM
Post #4


Senior Member
****

Group: Members
Posts: 3648
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (sci44 @ Nov 19 2008, 03:44 PM) *
Because it had a very good science package for the weight/price.

Exactly. The problem is it was almost too good a value of science/kg. My gut feeling is Falcon 1e could probably send something like 100 kg on a Mars transfer trajectory. That seems too small for a revised Beagle + cruise stage to me. If it were 200 kg I'd think it's doable, but 100... That would add 9 million $ for the Falcon + who knows how much for a solid 3rd stage to the bill.


--------------------
Go to the top of the page
 
+Quote Post
djellison
post Nov 19 2008, 03:19 PM
Post #5


Founder
****

Group: Chairman
Posts: 14431
Joined: 8-February 04
Member No.: 1



QUOTE (sci44 @ Nov 19 2008, 02:44 PM) *
Because it had a very good science package for the weight/price.


A smouldering pile of metalic rubble on the Martian surface doesn't do much science.

The weight/price was the problem. Not enough of either. Spend twice as much, on both, and you might buy a real chance of success.
Go to the top of the page
 
+Quote Post
sci44
post Nov 19 2008, 04:05 PM
Post #6


Junior Member
**

Group: Members
Posts: 63
Joined: 18-November 08
Member No.: 4490



QUOTE (djellison @ Nov 19 2008, 03:19 PM) *
A smouldering pile of metalic rubble on the Martian surface doesn't do much science.


Every Mars space program has had a few of those. smile.gif In fact you could say that about all the Russian landers really - it doesnt seem to stop them trying. Pillinger thinks that the atmosphere was thinner than planned, leading to late deployment of parachutes and airbags - maybe next time we can get MRO to check on that, as it did with Phoenix! He doesnt seem to believe that a probe this small cannot work, although I am sure you are right to say more weight in, for example, the heat shield would be of benefit. Remember the original Beagle design was a bigger probe - it was downsized by necessity.

QUOTE (ugordan @ Nov 19 2008, 02:52 PM) *
My gut feeling is Falcon 1e could probably send something like 100 kg on a Mars transfer trajectory. That


I wonder if its possible to use a SMART style ion drive stage, and spiral up from LEO? That could cut the weight down, and would make an interesting "test" mission. Otherwise yes, a bigger launcher and third stage. Or if you used the Falcon-9, would you need much in the way of an additional delivery system..
Go to the top of the page
 
+Quote Post
ugordan
post Nov 19 2008, 04:31 PM
Post #7


Senior Member
****

Group: Members
Posts: 3648
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (sci44 @ Nov 19 2008, 05:05 PM) *
I wonder if its possible to use a SMART style ion drive stage, and spiral up from LEO? That could cut the weight down, and would make an interesting "test" mission.

You would need largish solar panels on the cruise stage to provide juice to the ion engine. Not sure how much that adds, but since it's an overall lightweight spacecraft, it doesn't have to be many kilowatts to produce reasonable accelerations. The whole thing probably would fit inside Falcon 1e LEO payload (though you probably wouldn't want to be placed in a 185 km parking orbit, air drag would probably overwhelm ion accels).

The thing is: spiralling out of LEO just gets you on a heliocentric trajectory, you'd have to keep thrusting to raise the orbit to Mars. It's probably doable (say also using a Moon flyby to escape Earth), but it would take a long time. You'd probably have to take >1 year in heliocentric orbit alone while pumping the orbit. The plus side is the Mars entry velocity would be lower and easier on your heatshield than typical direct, Hohmann-ish Earth->Mars injections.


--------------------
Go to the top of the page
 
+Quote Post
ElkGroveDan
post Nov 19 2008, 04:59 PM
Post #8


Senior Member
****

Group: Admin
Posts: 4763
Joined: 15-March 05
From: Glendale, AZ
Member No.: 197



QUOTE (ugordan @ Nov 19 2008, 08:26 AM) *
Falcon 9 on the other hand is expected to be able to boost 1200 kg to a Mars transfer trajectory directly.


Keep your eye on that ball. There are a whole lot of plans for a whole lot of uses for the Falcons and Dragon and they will gain a lot of Earth Orbit headlines in the near future as Spacex builds a healthy space launch business. Ultimately though Mars was Elan's original motivation for starting Spacex in the first place. That's the unwrapped Christmas present at the back of the tree that no one is paying any attention to right now.


--------------------
If Occam had heard my theory, things would be very different now.
Go to the top of the page
 
+Quote Post
sci44
post Nov 19 2008, 05:02 PM
Post #9


Junior Member
**

Group: Members
Posts: 63
Joined: 18-November 08
Member No.: 4490



QUOTE (ugordan @ Nov 19 2008, 04:31 PM) *
You would need largish solar panels on the cruise stage to provide juice to the ion engine.. <snip> ..The plus side is the Mars entry velocity would be lower and easier on your heatshield than typical direct, Hohmann-ish Earth->Mars injections.


That sounds reasonable. Ok, launch mass SMART-1 367 kg, of which only 100kg was propellant. I dont know how much more weight/cost can be saved - most of the science intruments can go, although you may want to keep a simple camera for publicity shots and to aid navigation. Assume similar comms package could work - I would guess a directional antennea is not needed for low speed mission comms. Lets loose 20kg instruments, add 80 kg of xenon propellant (wild guess) plus Beagle-3 (69Kg) - about 500 kg. I'm sure someone else can do better than that, but its a start..

SMART got a "free" launch as a payload of oppertunity - maybe Elan will have a similar slot he can donate on F9..
Go to the top of the page
 
+Quote Post
ugordan
post Nov 19 2008, 05:05 PM
Post #10


Senior Member
****

Group: Members
Posts: 3648
Joined: 1-October 05
From: Croatia
Member No.: 523



Dan, I can't personally wait till the maiden Falcon 9 launch. I wish them success on the first try and am keeping my fingers crossed, but as a cautious skeptic I've got my reservations. Getting into orbit is hard, and we're yet to see how much of their advertised low price will hold after all the reliability factors are taken into account. It's one thing to get into orbit, it's a whole other ballpark to maintain a ~97% success rate at doing so.


--------------------
Go to the top of the page
 
+Quote Post
ugordan
post Nov 19 2008, 05:12 PM
Post #11


Senior Member
****

Group: Members
Posts: 3648
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (sci44 @ Nov 19 2008, 06:02 PM) *
SMART got a "free" launch as a payload of oppertunity - maybe Elan will have a similar slot he can donate on F9..

Doubt it. As I hear, the first F9 launch was supposed to be a demo flight, but Elon got a paying customer in the meantime. Probably a DoD payload, they tend to have old satellites rotting on the ground and they might as well afford the risk of launching it on an unproven rocket.

The F9 payload capacity (if indeed demonstrated) is nothing to sneeze at, it could easily haul another MER without the need for a solid third stage!


--------------------
Go to the top of the page
 
+Quote Post
ElkGroveDan
post Nov 19 2008, 05:15 PM
Post #12


Senior Member
****

Group: Admin
Posts: 4763
Joined: 15-March 05
From: Glendale, AZ
Member No.: 197



QUOTE (ugordan @ Nov 19 2008, 11:05 AM) *
Dan, I can't personally wait till the maiden Falcon 9 launch. I wish them success on the first try and am keeping my fingers crossed, but as a cautious skeptic I've got my reservations. Getting into orbit is hard


Agreed. But let me tell you at a gut level how impressed I am with this company and it's people at all levels. I've seen a lot of government projects and I've been involved with a lot of businesses with ambitious plans. However I have never seen the kind of dedication, enthusiasm and excitement among a team of people as you see with the folks at Spacex. On top of that Elan with his personal commitment and big fat checkbook backing them up, really gives me reason to be optimistic. If it can be done, these guys will do it.


--------------------
If Occam had heard my theory, things would be very different now.
Go to the top of the page
 
+Quote Post
sci44
post Nov 19 2008, 05:41 PM
Post #13


Junior Member
**

Group: Members
Posts: 63
Joined: 18-November 08
Member No.: 4490



QUOTE (ugordan @ Nov 19 2008, 05:12 PM) *
Doubt it. As I hear, the first F9 launch was supposed to be a demo flight..

Sorry, to clarify, SMART was added as a third small additional "free" GTO payload with 2 larger packages. Since F9 can take 5000-12000kg to GTO (10000-27000kg to LEO) maybe one of the future missions may have 500kg spare/donated for an interesting concept like this. Remember we would be talking some time down the road. Sure, if you can get a whole F9, send it direct, but of course you need to either pay for all of it, or share the payload with someone else en-route to Mars..
Is that right about LEO being insufficient for an ion craft launch?
Go to the top of the page
 
+Quote Post
ugordan
post Nov 19 2008, 05:51 PM
Post #14


Senior Member
****

Group: Members
Posts: 3648
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (sci44 @ Nov 19 2008, 06:41 PM) *
Is that right about LEO being insufficient for an ion craft launch?

I don't know, that's arm-waving on my part, but a low orbit such as a low parking one ought to be unstable on an order of several days. Since you're bound to be in shadow half the time, your thrusting is even more limited during that period. Ion engines provide a gentle enough thrust that there must be a point when the LEO drag is stronger than prograde thrust. SMART-1 for example was launched into an elliptical geostationary transfer orbit which helps a lot both for thrusting periods and reducing atmospheric drag. Ideally, you'd want to do the same here.

F1e has miserable payload to that kind of orbit so, yes, your best bet would be a piggyback on an F9. The problem is, noone really knows the exact payload capacity that thing has/will have, even SpaceX data are contradictory and the projected capacity tends to decrease with each successive F1 launch. The "Falcon Lunar Capability Guide" says F9 can boost something like 1600 kg to Earth escape, while the "F9 Data Sheet" gives a much larger 2500 kg. I suspect the former is true based off of some analysis on NSF.com.


--------------------
Go to the top of the page
 
+Quote Post
Del Palmer
post Nov 19 2008, 11:33 PM
Post #15


Member
***

Group: Members
Posts: 213
Joined: 21-January 07
From: Wigan, England
Member No.: 1638



With all this talk of ion propulsion and Mars, I'm surprised no-one has mentioned Dawn...

Go to the top of the page
 
+Quote Post

2 Pages V   1 2 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 28th March 2024 - 12:48 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member.