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...I don't see how you can start with a singleton lump closed system that's supposed to respect conservation of energy and conservation of mass in the framework of SR...
Stop right there  :).  Nowhere in the above considerations have I  considered conservation of energy.  I only addressed conservation of momentum, so far.
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If there was no incl change doesn't super sync still mean less delta-v to circularize?

No, if you had a craft in an 0 inclination equatorial LEO then putting it into an elliptical orbit with an apogee equal to the perigee and apogee of the target circular GEO orbit it would require less impulse to in a single impulse at apogee to circularize the orbit than the sum of the two impulses needed to raise the perigee then lower the apogee. Though each of those impulses individually would be lower than the single impulse needed to circularize the orbit in the direct case.
So the only advantage of super sync is to do the plane change at the lowest possible velocity.
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Missions To Mars (HSF) / Re: Mars One Discussion Thread
« Last post by Astro_Osk on Today at 09:56 PM »
Welcome Astro_Osk :)

Flat out they should be exchanging emails and phone calls with Caterpillar (or the European equivalent thereof, but Cat has already given presentation on work they have done which I haven't seen from anywhere else) over the rover design. Cat has gotten as far as testing various lubricant's and fluids for use in "space" conditions and lets face facts this "rover" is going to be MUCH more 'tractor' than anything previously seen or designed.

Randy

Thank you for the welcome--you make some excellent points.

Hopefully we can discuss them at length :)

Quote
With respect to your Caterpillar comments, I will ask Mars One if they can disclose any past, present or planned outreach to Cat (or equivalent) as potential rover partner.  I'll let you know if they have a response!

Thanks!

As noted Caterpillar is the only company that's done any in-house work on modifying their equipment for use in space, and while I understand there are other companies that design and produce "rovers" what is being asked of the Mars One rover is much more akin to something you'd see from Caterpillar (Bobcat really since hey have off-the-shelf remote and automation options but I'm sure there are companies in Europe as well) than say the makers of MSL or Curiosity.

Randy

I know Mars One had some initial contact with Astrobotics concerning a rover, but perhaps they did not reach out to Cat.  This is the first I've heard Cat working on off-world construction equipment, so maybe I'm not the only one.  Very interesting to know, however.
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Dr Rodal, you insist that you are here doing a study of a closed system composed of a single lump of mass, i.e. that there is no separation (separation in 2 parts from a single part, as would be the case for action/reaction) nor joining ("melting" of 2 parts in a single part, as would be the case for an inelastic collision/aggregation) nor bounce (2 parts exchanging momentum but still being separate before and after such interaction). Do I understand correctly your premise ?

If so, in a given frame, considering one lump of rest mass m1 at velocity v1 and associated γ1=γ(v1) before, and same singleton object of rest mass m2 at velocity v2 and associated γ2=γ(v2), taking both conservation of momentum and of (total) energy gives (following the equations you recall) :
γ1 m1 v1 = γ2 m2 v2  (CoM)
γ1 m1 c = γ2 m2 c  (CoE)
⇔ (since c≠0)
γ1 m1 v1 = γ2 m2 v2
γ1 m1 = γ2 m2

γ1 m1 v1 = γ1 m1 v2
γ1 m1 = γ2 m2
⇔ (since γ1≠0)
m1 v1 = m1 v2
γ1 m1 = γ2 m2

Now, all depends on m1

m1=0, total mass of the closed system is 0 from start
since γ2≠0 ⇒ m2=0 : it must be that total mass stays 0
and v1 and v2 are independant

m1≠0, total mass of the closed system is not 0 from start
since m1≠0 ⇒ v1=v2 : it must be that velocity stays the same
and so γ1=γ2 and it follows that m1=m2

I don't see how you can start with a singleton lump closed system that's supposed to respect conservation of energy and conservation of mass in the framework of SR, even assuming possibility of negative rest mass (or imaginary rest mass, whatever) and not arrive at same conclusion. There appears to be a contradiction between your premise (closed system) and the conclusions you draw from equation of conservation of momentum alone, when a closed system needs both constraints to be taken together.

Also it is not clear how you consider mass...
.../...
where, in the above equation and in the ones to follow, m is the rest mass m=mo, the mass of an object in its rest frame.  Also, as already discussed here: http://forum.nasaspaceflight.com/index.php?topic=39214.msg1488362#msg1488362 the InitialVelocity must be measured with respect to the same frame where the InitialMass of the object was measured.  This is an acceleration problem, hence the frame where the rest mass is measured is a privileged, non-inertial frame.   If other frames of reference are used, not only the Initial Velocity will be different, but the Initial Mass will be different too, if measured in any frame other than the object's initial frame of reference to measure its mass.
.../...

<<m is the rest mass m=mo, the mass of an object in its rest frame.>>
All right so we are not using so called relativistic mass mrel, and by avoiding the traps of mrel we are conforming to prescriptions of modern physics teaching. Fine with me. That means that whenever we talk about mass we can be confident that is not mrel(v) a function of velocity, i.e. a covariant value that depends on inertial frame of reference, but we talk on an invariant value, that has the exact same value for all observers. The fact that we are talking of this invariant mo mass appears clearly in the equations, as for instance momentum is given by p=γmov otherwise we would have p=mrelv. To me it then appear as a contradiction to use mo in the equations but to discuss those very same variables as if they were a function of velocity :
<<but the Initial Mass will be different too, if measured in any frame other than the object's initial frame of reference to measure its mass. >>

And I fail to see the physical meaning of  <<InitialVelocity must be measured with respect to the same frame where the InitialMass of the object was measured>> that again seem to imply the use of mrel that is a function of velocity wrt. observer, when all equations use the invariant mo that is not a function of velocity wrt. observer

But all those question are less important than the first part of this post : unless we are talking of a 0 total (invariant) mass object from start, in SR a closed system single object with mo≠0 just has an inertial trajectory of constant velocity and constant (invariant) mass, in this later case the hypothesis of occurrence of negative mass doesn't change the game.
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The satellite might use passive magnetotorque or gravity gradient stabilisation, and have no active RCS systems, in which case it will take a while to stabilise. Early days!
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If there was no incl change doesn't super sync still mean less delta-v to circularize?

No, if you had a craft in an 0 inclination equatorial LEO then putting it into an elliptical orbit with an apogee equal to the perigee and apogee of the target circular GEO orbit it would require less impulse to in a single impulse at apogee to circularize the orbit than the sum of the two impulses needed to raise the perigee then lower the apogee. Though each of those impulses individually would be lower than the single impulse needed to circularize the orbit in the direct case.
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James has confirmed ASDS landing: https://twitter.com/flatoday_jdean/status/696816102010200065

Looks like the rocket/bottle bank's still open for deposit ;)

Wait, a super-synchronous insertion with a 5,300kg payload AND a stage 1 return?

O_o

This means more than 30% better GTO performance for the FT over v1.1 . It's a beast! (or some part of the information we have about the mission is incorrect).
Did anyone actually confirm that this was not subsyncronous on FT? Otherwise it might still be, just less so...
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I'm torn as to whether this belongs here, or in the party thread. If I'm wrong, I'd appreciate it if a mod nuked this post.

The reason I picked this thread is it's something that happened on an ASDS, OCISLY. A wedding.
https://twitter.com/Restrantek/status/696321709134241793

Finally!... A successful landing on an ASDS. OCISLY. ;D

They could make some money outta this.. maybe even enough to cover the berthing fees.
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James has confirmed ASDS landing: https://twitter.com/flatoday_jdean/status/696816102010200065

Incredible. Thanks.


IIRC SES wanted the opportunity to reuse the SES-9 S1, assuming all went well.  It makes sense that their modified launch profile would not preclude an ASDS landing attempt.
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James has confirmed ASDS landing: https://twitter.com/flatoday_jdean/status/696816102010200065

Looks like the rocket/bottle bank's still open for deposit ;)

Wait, a super-synchronous insertion with a 5,300kg payload AND a stage 1 return?

O_o

This means more than 30% better GTO performance for the FT over v1.1 . It's a beast! (or some part of the information we have about the mission is incorrect).
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