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SpaceX Reusability / Re: SpaceX customers' views on reuse
« Last post by FutureSpaceTourist on Today at 02:19 AM »
Not sure if this has been noted, but two boosters (1046/7) have completed double GTO flights.  Customers don't seem to be worried about reusing these stages after high energy launches/recoveries.

True and of course 1046 has had 2 GTO flights and about to be re-used again. I imagine that as this point - after so many booster reuses - most customers just trust that SpaceX know what they're doing. Should be plenty of data on the comparative condition of boosters after LEO and GTO flights etc.
Hi, I recently saw a table on ProjectRho suggesting that a BFS had the delta-v to travel between the 9 or so major moons of Saturn, and trip times were also only on the order of days instead of months, and I thought "that is the Flash Gordon future that was promised us!" .. but how would we survive there? Most importantly what do we do for power when solar may no longer be an option?

Where do you see that? AFAIK, it is impossible with chemical rockets.

IIRC that is with a BFS fully top up with propellants at a local propellant depot in Cis-Saturn space.
You can find it by following that link and searching the massively long page for "Moons of saturn" .. I don't know why they dont have html anchors so I could link to it directly.. it is not rocket science! :)

It is a nice site for hard SF info. The person did note these values were only representative, probably using the simplest formula assuming circular orbits and no other bodies etc.. Im guessing.
<SPP.jpg (second image from bottom in post)>
Any idea what those tall metal strut towers are in this picture? Are those related to the launch site (if so, wow that's huge, where did that come from overnight?!...), or are they something else like distant cranes at the port?
Space Science Coverage / Re: NASA - Kepler updates
« Last post by Targeteer on Today at 02:07 AM »
Laboratory for Atmospheric and Space Physics 4 hrs · Facebook

Kepler Telescope Bids 'Goodnight' with Final Commands

On the evening of Thursday, Nov. 15, NASA's Kepler space telescope received its final set of commands to disconnect communications with Earth. The "goodnight" commands finalize the spacecraft's transition into retirement, which began on Oct. 30 with NASA's announcement that Kepler had run out of fuel and could no longer conduct science.

Coincidentally, Kepler's "goodnight" falls on the same date as the 388-year anniversary of the death of its namesake, German astronomer Johannes Kepler, who discovered the laws of planetary motion and passed away on Nov. 15, 1630.

The final commands were sent by University of Colorado Boulder student command controllers over NASA's Deep Space Network from LASP's Kepler Mission Operations Center.

The Kepler and K2 Missions team disabled the safety modes that could inadvertently turn systems back on, and severed communications by shutting down the transmitters. Because the spacecraft is slowly spinning, the Kepler team had to carefully time the commands so that instructions would reach the spacecraft during periods of viable communication. The spacecraft is now drifting in a safe orbit around the Sun, more than 100 million miles away from Earth.

Kepler has had a profound impact on our understanding of the number of worlds that exist beyond our solar system. Through its observations, we've discovered there are more planets than stars in our galaxy. The data Kepler collected over the course of more than nine years in operation will be mined for exciting discoveries for many years to come.
The full paper is here:

they hit mice with 10 Sv of heavy ions... This compares unfavorably with the estimated 1 Sv total dose (mostly from protons, not heavy ions) for a 860 day Mars mission...

Looking at their reasoning and method:

While protons are the major component of space radiation, energetic heavy ions such as 56Fe, 28Si, and 12C contribute significantly toward the dose equivalent, and ∼30% of astronauts’ cells are predicted to be hit by heavy ions during a round trip to Mars...

Since the estimated radiation dose for a 1,000-d Mars mission is about 0.42 Gy (21), with an estimate of an 860-d Mars mission dose equivalent of ∼1.01 Sv (22) so doses of 0.5 Gy or less are more relevant, we have used 0.5 Gy to study IEC migration, which is important for intestinal homeostasis.

Wild-type mice... were irradiated (dose: 0.5 Gy) using a simulated space radiation source at the NASA Space Radiation Laboratory (NSRL), Brookhaven National Laboratory for iron (56Fe; energy: 1,000 MeV per nucleon; LET: 148 keV/μm) irradiation, and a 137Cs source was used for γ-ray (LET: 0.8 keV/μm) whole-body irradiation of mice.

How did you calculate 10x overdose?

0.5 Gy of 56Fe is 10 Sv, already more than 10x the estimated biological effective dose of ~1 Sv for a 860-day Mars mission.

Factor in shielding, dose rate, dose mix, etc. and this has no basis in reality for an actual Mars mission.

Even that 1 Sv dose is based on  wrong assumptions.
       you are correct, I do not understand how anyone could think of fields as being anything more than illusions created by a misinterpretation of the nature of electromagnetic interaction. But, being as GR is the zeitgeist and you will defend it with all the zeal of a true believer, all I can do is wish you satisfaction.
       Meantime, the possibility remains that am emdrive or a MET will one day prove itself with undeniable thrust measurements. What I am attempting to do is preempt the necessary considerations which will then follow. How could that be possible, if it proves to be happening. GR, QM and the Standard Model are not going to help you much if that happens.
So you ask a question, don't like the answer, and resort to incorrect ad hominem attacks rather than address what was said.My previous post had nothing to do with GR, and what I was describing about basic facts about how electromagnetism works with reflection is based on well tested experimental regimes. The results of previous experiments won't change if some new physics is discovered. Denying what we already know happens will not help you understand any new physics if it were shown to exist.
       ad hominem attacks!


 Personal Message (Online)
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« Sent to: spupeng7  on: 11/15/2018 12:09 AM » 

Your most recent post is little more than an insult, so it is against site rules for me to reply to it in the thread.

You can measure the existence of fields. There are experiments that demonstrate all of the properties known in electromagnetism. However, because you find these results unintuitive, you refuse to accept them, and keep making poor attempts to cram those facts into your personal model of the universe, simply refusing to acknowledge the inconsistencies. Your random mention of GR in response to a post that has no relation to GR only serves to demonstrate that you have no interest in understanding.

At this point you appear to have comparable interest in scientific research to a flat-earther. You deny and distort the facts, and when that fails you resort to insults. I find your continued insistence that fields can't be real things with no justification other than you don't understand them nearly incomprehensible. My only explanation is a severe case of Dunning–Kruger, since you seem to think you are the only one on the planet who is right. (The fact that you don't understand fields is not what confuses me, that is obviously because you have made no apparent attempt at understanding.)

       all I said was that I can not understand how anyone could think of fields as being anything more than illusions created by a misinterpretation of the nature of electromagnetic interaction. Oh and wished you satisfaction. This is not a debate closed to alternative viewpoints, so long as they are genuine. Your refusal to accept my opinion is of little consequence unless the science you are defending is at the very least seamless and complete :)
SpaceX Es'hail-2 Launch - UP CLOSE VIEWS

Published on Nov 16, 2018

Chinese Launchers / Re: Chinese 2020 Mars rover?
« Last post by Steven Pietrobon on Today at 01:26 AM »
Scientific Objectives and Payloads of Chinese First Mars Exploration

Cool! Attached is the full paper.
SpaceX BFR - Earth to Deep Space / Re: A BFR Ocean Launch Platform
« Last post by aero on Today at 01:25 AM »
Re-visiting the question of, "Why not off the coast of California?" We all seemed to forget the most obvious reason which is that the launch trajectory would go over heavily populated land.
No, because the tankers that do the filling flights can be shared between the multiple BFS depots waiting in orbit.

Your math only works if you assume one BFS flight. But aside from perhaps the first unmanned launch window, there would always be a fleet. And with filling up a fleet, the infrastructure is shared. That tanker BFS that does 5 flights could in theory fly 100 times to fill up 20 depots. Make sense?

If you assume that, then your proposal requires a lot more than twice the number of BFS tankers, because a single BFS tanker can also be shared among many BFS Mars space ships using the second method I outlined, i.e. the method shown in the SpaceX IAC 2017 slides.

So for example, if they're launching 6 Mars BFS ships, your proposal would require 7 BFS tankers in orbit, where the SpaceX method would only require 1.

Remember, Musk is talking about multiple launches of the same rocket within 24 hours, even for Block 5.
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