Search results

"NASA has certified the current version of the SpaceX Falcon 9 to launch some categories of science missions" If I have understood correctly SpaceX is not producing 'current version' any more. NASA's certification process is too slow or SpaceX development speed too high.

I don't think I have called Amos 6 as a launch failure. I know my English is bad, but I am careful with key words. I will be calling it failure or failure while preparing for launch. They were doing that. If title is 'launch failures' then you could exclude Amos 6. That is not a stat...

No I didn't. I don't know much about manufacturing. So I'll try to compare how complex products are. I think Elon said 10* production rate cut productions costs to half. That makes sense, but rocket production rate is too low. If they are limited by fairing production, then I go back to my...

6 M$ for fairing makes it roughly as expensive as 2.stage. Merlin must be much cheaper than 6 M$, because F9 has 10 Merlins. So I have trouble understanding fairing price. I found support for my ideas: Cost calculation for Falcon 9 & Falcon Heavy • r/spacex

Amos 6 failure happened during preparation for launch not during launch. If I'm hired to move a piano and I break it while backing it for transport, I should not explain to client that I did not broke it during transport. You can draw a line between preparation for launch and launch, but I'll...

As I understand this: Precession rate depends on altitude. Change of altitude will change orbital plane relative to satellites on different altitude. Those satellites must have large batteries for operation on night side. So ion-drives could be used on night side also. I think I could...

Acceleration (trust) of ion drive is limited by available power. These satellites might have rather large solar panels anyway. Dawn used ion drive about 2.5 AU from the Sun. Earth gets 6 times as much solar energy. LEO satellite is on shadow half of the time, so only 3*. With ion drive...

I think they have 2 failures, because they have lost main cargo twice. 25 launches without issues is a reason to celebrate.

I don't see large calculation errors (didn't check small ones:) Are you planning 2. stage with larger propellant tanks? I don't think SpaceX will do it, because launch cost of BFR should be smaller than launch cost of F9. I think they should copy ion drive from Dawn Mission | Mission...

After thinking this (and sleeping), I decided my first idea is correct. Change of orbital plane requires change in direction of velocity even if inclination is same. Doing that with v=sqrt(earthmass*G/(1150 km + earthradius)) = 7.281 km / s is difficult. This makes BFR less efficient in...

My first thought: No, it takes too much delta-v to change between LEO orbital planes. Fully reusable F9 would be good. Before posting I thought again: Inclination is same, so perhaps delta-v is not too high. At least if you have time. LEO constellation has 5 different inclinations and VLEO...

I did read Technical Attachment:) "Each satellite in the SpaceX System is designed for a useful lifetime of 5 to 7 years." So they need to get them to orbit in less than 5 years. LEO constellation has 83 orbital planes, so 83 launches is needed, more for 7518 VLEO satellites. VLEO is low...

Extinction causing asteroids are rare. Planet sterilizing even more rare. But city killer size asteroids come once in 100 - 200 years. For example Tunguska event - Wikipedia was about 1000 times more powerful than nuclear bomb dropped to Hiroshima. It would be very useful to detect these...

Of course there is. My purpose was to find order of magnitude. So what is wrong with this: Last change to orbit was made close to Earth, so orbits of Roadster and Earth will intersect on that point. Earth moves its own diameter in less that 7 minutes -> 7 min/year = 1.3e-05 In 100 000 years...

I agree, but I still think 2. stage is much more complex. Aerodynamic forces attacking fairing will be passed to 2. stage. It also has a rocket engine. Fraser Cain claims: Each RS-25 probably cost NASA around 60 M$. SLS uses 4 of those.

Electric motor might crash to surface of Earth, everything else only to atmosphere with speed about 15 km/s. Unless it comes in almost horizontally, most of that speed will be dissipated in one second. Anyway I trust orbit simulation more than my simple calculation.

It needs to be strong. It needs to reliably separate from rocket. It is relatively simply compared to 2. stage. Mass in 2. stage is more harmful than in fairing, because fairing does not go to orbit. Based on this it should cost 1/10 of 2. stage.

Yes, because they are developing recovery. I don't know why. It is very large. It must be very light and rather strong. Perhaps it is hand made piece of carbon fiber. I imagine automating fairing production could be alternative for recovery and reuse. This is about money:)

Don't wait too long: What now for SpaceX's Mars-bound Telsa Roadster? Very simple calculation shows it will probably crash into Earth in 100 000 years. Simulation is of course more accurate. Perhaps gravity of Jupiter and Earth will change orbit so that it less likely to hit Earth.

Not many free parking places. Perhaps 1/3.

Since BFS could reach orbit without booster (and cargo), it could reach Florida also. But would SpaceX get landing permissions? Usually rockets aim to equator 10 000 km east from launch site. Cuba is in better position than Florida. With spaceflight101.com numbers F9 1. stage is 79 % of...

From Grendals post: Elon, when asked about improving the second stage: "Under consideration. We’ve already stretched the upper stage once. Easiest part of the rocket to change. Fairing 2, flying soon, also has a slightly larger diameter. Could make fairing much longer if need be & will if BFR...

OK. Give them opposable thumbs and neocortex equivalent. Without space program their civilization would have collapsed anyway. Then small mammals would eaten their eggs during cold nights. It has been calculated that asteroid with 500 km diameter would kill last bacteria from Earth. We know...

If you deliberately spill RP-1 into sea here, you will be fined. With large spill you could end up in prison. I don't think local law even knows RP-1. It is an oil very close to lamp oil. Perhaps snake-oil seller would sell lamp oil as CnH1.953n. That formula tells only it is hydro-carbon...

Kessler syndrome is serious issue on high orbits, but it is not a problem on LEO. Read wiki page you linked.

Since orbit intersects Earths, it will come back eventually. But not soon since Earth is very small target. Very quick calculation: It will come back in 100000 years.

What do you think RP-1 - Wikipedia is?

Dinosaurs died because they did not have space program. Extinction size asteroids are of course rare. City killer size asteroids come once in 100 - 200 years. (Tunguska event - Wikipedia was 10 - 30 megatons)

Roadster goes 243 / 142.0 = 1.71 times as far as Mars from the Sun. (Using numbers from your post.) I understood that orbit is tilted, so it does not actually intersect orbit of Mars. They could not avoid intersecting Earths orbit. I believe this limits its travel time.

I don't believe it is bulletproof. Difficult part is to recover oil in it.

F9 is not designed to survive force of waves. If fuel tank survives waves, small handgun is enough to sink it. Problem is small amount of fuel left in it. Perhaps they hired somebody to try to recover fuel.

I liked it. Moon base will be for science, mining and hotel for rich, but it is necessary before any real colonization.

Air pressure at F9 1. stage separation is so low that liquids boil as in vacuum. Extra altitude will make no difference.

Youtuber published on Feb 6, 2015 new version of that car landing video: ______________________*******

Why did it happen on two engines, but on one? Random event seems unlikely. Perhaps human error: It was prepared for single engine landing.

Weird! Your message claims to quote mine, but quotes ccutrer's message. (406) I thought Roadster's orbit would stay between orbits of Mars and Earth to avoid risk of collision. They avoid that by tilting orbit. I guess they don't need to prove their aim. Success of the launch is very good...

Elon in upper video: "It will be coasting for 6 hours" When engine stops last time, orbit cannot be changed. It will travel 6 h away for Earths orbit, then change to new orbit, which will not intersect Earths orbit. This is not needed for satellites going to Mars.

Yes, I admit rocket + wings is not practical. Stratolaunch disagrees: "We are excited to report all objectives of this test were achieved – culminating to the aircraft traveling down the runway at 25 knots (28 miles per hour)." Stratolaunch News Giant zeppelin would be very valuable in...

Replies to Discussion of Numerical Punctuation Mg is official SI unit: International System of Units - Wikipedia versions of ton are not. My translation of local law as I understand it (not a lawyer): "SI units must be used when measurement is required by law or has economic value or has...

Lack of cargo space limits FH capacity to low orbit. For high orbits, Moon and planets it has enough cargo space. SpaceX has not yet saved significantly with reuse. (If it can be used only twice, it needs lot of service between flights.) Block 5 will change that. There is nothing wrong with...

But it is not dead. Wikipedia: A second airframe with a slightly different configuration[1] was partially built. Its construction was halted in 1994[1] because of lack of funding and interest, but revived briefly in 2009, bringing it to 60–70% completion.[2] On 30 August 2016, Antonov agreed to...

I don't see any reason to call FH a weak idea. I can imagine good reasons why it is late: F9 has been developed to carry much heavier loads, so need for FH is reduced. It is difficult to develop FH from F9 components, when those components are changing. I haven't seen any numbers how much...

That does not prove their idea was bad (perhaps it was, I don't know). They incorrectly assumed they can get more investor money without prototype.

Empty 1. stage of BFR weights about 150 t. Antonov An-225 Mriya - Wikipedia can take 200 t external load. Cargo hold is 6.4 m (21 ft 0 in) wide. BFR stage would add lot of air resistance with rather large torque. Perhaps that's too much. CargoLifter - Wikipedia was designed to carry 160 t...

Less propellant is needed. Risk is higher, because burn is started at low altitude. Dry mass: 22.1t Thrust 3*420 kN Over 5 g deceleration (ignoring air resistance). With 5g: 0.57 s from 100 km/h to 0 in 8 meters.

Lunar eclipse lasted 76 min. That is about 1/500 of a month, so Moon is at perigee during 1 out of 500 eclipses. Partial eclipse lasted 3:23. Perigee is once out of 200 partial eclipses. With 1.5 eclipses on a year that makes one perigee during 130 years. Of course perigee same day as...

Perhaps they tested shorter re-entry burn or none and did not expect it to survive.

Moon at perigee and a total lunar eclipse same time is rare. Moon looks larger at perigee, but difference is not enormous. I haven't checked, but every 150 years or so is probably correct.

Studying google.maps: Houses behind antennas are Boca Chica Village, Texas - Wikipedia Those houses will not be expensive problem for SpaceX.