falcon 9

[Findthepin1]

How much mass can a Falcon 9 rocket get to a trajectory towards Jupiter? What about Venus or Mars?

[Guest]

Falcon Nine payload is a fraction of what the SLS can offer. You'd need 4 launches for a manned mars misson.

Just sat through a presentation from a ESA rep and asked him about the F9/SLS situation, so can't give you accurate figures as it was just a discussion.

[xenomorph555]

You'd need 4 launches for a manned mars misson.

Impossible, you may be thinking of Falcon heavy (50t LEO) for 4, but Falcon 9 (13t LEO) would take over 20 rockets for a basic Mars mission.

[Frozen_Heart]

Falcon 9 isn't designed with Mars missions in mind. Its much more optimised for delivering payloads to earth orbit.

I doubt that even an empty F9 stage could get to Jupiter.

[Kibble]

About 1465 kg on a Mars transfer, and about 1776 to Venus. Falcon 9 can't get anything to Jupiter without an upper stage.

[AngelLestat]

depending the payload you want to carry.. to jupiter or venus or mars.

So you need to start from there, 100kg? 1 ton? 5 tons? 22 tons?

Kibble are you sure of that? How much the falcon9 can carry to GEO?

[Frybert]

depending the payload you want to carry.. To jupiter or venus or mars.

So you need to start from there, 100kg? 1 ton? 5 tons? 22 tons?

Kibble are you sure of that? how much the falcon9 can carry to geo?

4850 kg

[1greywind]

To launch something to interplanetary trajectory with F9 (2 stage in basic configuration) you need to add some upper stage to it. F9 1.1 can lift ~13 ton to LEO. Let us see that upper stage we can put on it:

- Centaur with it's 23 full mass is out of question.

- Block D is ~19 ton, next.

- Fregat ~7,7 mass. Looks like that we need.

Well. Next we google for Solar system dV map - http://i.imgur.com/AAGJvD1.png.

Look for dV needed to reach low Mars orbit from LEO - 5710 m/s

Check Isp of Fregat's engine (á5.92) - 326 s

Drop numbers into rocket equation to get ln of minimum mass fraction:

5710 = 9.8 * 326 * frac

frac = ln (fullMass / dryMass) = 1.78

fullMass / dryMass ~= 5.95

Fregat's dry mass is 1 ton. So we need to solve simple equation:

(7.7 + x) / (1 + x) = 5.95

5.95 + 5.95*x = 7.7 + x

x = 1.75 / 4.95

x ~= 350 kg

Oh. Those 350 is not just "mass to Mars Homman transfer trajectory". It is mass delivered to low Mars orbit. Not bad mass at all. Some of best imaging satellites are twice lighter.

Edited May 5, 2015 by 1greywind

[Kryten]

Kibble are you sure of that? How much the falcon9 can carry to GEO?

Can't do GEO because the second stage doesn't have enough loiter capability, GTO payload is about 5 tons. Note that that's a 1,800m/s deficit GTO, most other operators quote 1,500m/s.

[Kibble]

Oh. Those 350 is not just "mass to Mars Homman transfer trajectory". It is mass delivered to low Mars orbit. Not bad mass at all. Some of best imaging satellites are twice lighter.

Wow Falcon-Fregat sounds like a lot of fun!

[Ralathon]

To launch something to interplanetary trajectory with F9 (2 stage in basic configuration) you need to add some upper stage to it. F9 1.1 can lift ~13 ton to LEO. Let us see that upper stage we can put on it:

- Centaur with it's 23 full mass is out of question.

- Block D is ~19 ton, next.

- Fregat ~7,7 mass. Looks like that we need.

Well. Next we google for Solar system dV map - http://i.imgur.com/AAGJvD1.png.

Look for dV needed to reach low Mars orbit from LEO - 5710 m/s

Check Isp of Fregat's engine (á5.92) - 326 s

Drop numbers into rocket equation to get ln of minimum mass fraction:

5710 = 9.8 * 326 * frac

frac = ln (fullMass / dryMass) = 1.78

fullMass / dryMass ~= 5.95

Fregat's dry mass is 1 ton. So we need to solve simple equation:

(7.7 + x) / (1 + x) = 5.95

5.95 + 5.95*x = 7.7 + x

x = 1.75 / 4.95

x ~= 350 kg

Oh. Those 350 is not just "mass to Mars Homman transfer trajectory". It is mass delivered to low Mars orbit. Not bad mass at all. Some of best imaging satellites are twice lighter.

You could improve the payload by aerobraking at Mars. That way you can shave a few hundred dV of the journey, since you only need to put yourself into a highly eccentric Mars orbit, instead of LMO.

[Kibble]

You could improve the payload by aerobraking at Mars. That way you can shave a few hundred dV of the journey, since you only need to put yourself into a highly eccentric Mars orbit, instead of LMO.

That didn't work out so well last time we tried it.

[Ralathon]

That didn't work out so well last time we tried it.

Worked just fine for the Mars Global Surveyor, Mars odyssey and Mars Reconnaissance Orbiter.

[Kryten]

As a sanity check, the only (proposed) mission I'm aware of to use a Falcon 9 at Mars is the PADME discovery proposal. No mass has been given as such, but's closely based on the LADEE lunar spacecraft, meaning a wet mass of about 400kg. Intended to enter orbit and have enough propellant left to make multiple Phobos and Deimos flybys and be retired into heliocentric orbit at end-of-mission.

[AngelLestat]

There is something wrong with your assumptions 1greywind, also the ISP you use is very low and the deltav very high, there is not much difference in deltav with GTO vs Mars.

Take a look to the Falcon heavy numbers:

Falcon Heavy would be able to lift a surprising 53 tonnes to LEO, 19 tonnes to GTO, or 13.6 tonnes toward Mars.

If we are talking of payloads lower than 1 tons, then is possible try aerobraking in mars, then in the venus case you dont have any problem with aerobraking.

[Guest]

Impossible, you may be thinking of Falcon heavy (50t LEO) for 4, but Falcon 9 (13t LEO) would take over 20 rockets for a basic Mars mission.

My apologies, I wrongly assumed he meant Falcon 9!

It was also very interesting hearing about the economic situation between the two craft. It's estimated that a SLS Mars launch would cost ~1bn (two launches) and the economic turnover would bring ~3bn into the economy. While the Falcon option is cheaper initially, it cannot bring that kind of growth.

- - - Updated - - -

That didn't work out so well last time we tried it.

You might be thinking of aero capture, which would not work well with current tech at all.

[1greywind]

ISP you use is very low and the deltav very high

Fregat upper stage uses N2O4/UDMH combo so it has low Isp. And dV is combined for: Earth escape, Earth-Mars transit trajectory insertion, Mars low orbit insertion burns. 350 kg is mass delivered to circular low Mars orbit. Not just "to Mars trajectory".

[Dkmdlb]

While the Falcon option is cheaper initially, it cannot bring that kind of growth.

It's not growth. It's just moving money from one place to another. A sort of smearing.

[Frozen_Heart]

Falcon Heavy would be able to lift a surprising 53 tonnes to LEO

No it won't. No even close. Without the fuel crossfeed as is currently planned the payload will be closer to 40 tons. In addition to that SpaceX don't want to use it as an expendable rocket which will half the payload again to about 20 tons.

However this makes much more sense economically as the aren't any 50 tons payloads, but plenty of payloads around 10 - 20 tons which the Heavy will be able to do.

[Kryten]

Like what? When's the last time anybody put a 10+ ton payload into LEO?

[Frozen_Heart]

Like what? When's the last time anybody put a 10+ ton payload into LEO?

Almost all the main ISS modules for one. I'm pretty sure that there will be another space station at some point in the future and the Heavy is the only current rocket which would be suitable for building it.

[Kryten]

That's not exactly 'plenty', is it? That's a few purely theoretical payloads.

[Rakaydos]

Like what? When's the last time anybody put a 10+ ton payload into LEO?

If tey can get the reusability straightened out, you get more saving reusing a bigger rocket, as most of the overhead ground side stays the same and fuel cost is negligable. If that savings get passed to the customer, you'll see more large, multipurpose satelites that dont kessler near-earth space as badly.

[Guest]

Almost all the main ISS modules for one. I'm pretty sure that there will be another space station at some point in the future and the Heavy is the only current rocket which would be suitable for building it.

SLS will be ready a good time before that's necessary.

[Hcube]

Like what? When's the last time anybody put a 10+ ton payload into LEO?

Very often with dual-satellite launches. See ariane 5 for example : it pretty much never launches single satellites, but regularly some medium sized satellites, 2 in 1 launch.

And sometimes you do see really huge satellites like terrestar1 or so...

The fact that only few payloads are 10+ tons is precisely due to the limitations of the launchers... If (should i say "when" ? ) launchers big enough to launch 40t payloads in orbit were(will be?) common, you would(will?) see loads of those around.