Discussion Your Venus/Mars mission concepts/proposals

[Nicholander]

Hmm... Interesting, but I think 1.32 kW is a bit too much for PADSL, so about how much energy do MARTE's solar panels make? And what is there mass?

Also, I think another way to do the multistaging to get almost 3 km/s of DV could be to just jettison side fuel tanks as they become empty. This avoids having to have 3 separate propulsion systems (Engines and such) for the 3 stages.

 

[ISProgram]

I've just finished, and though I didn't do it with the Delta Glider (I did it with the UCGO Shuttle-A), it's about 550 m/s of delta-v. So, say about 1 km/s of delta-v to get into the very elliptical orbit (use aerobraking to get it's apoapsis down), 300 m/s for course corrections getting to Mars, the 550 m/s for intercepting Phobos, and the 745 m/s for getting to Deimos from Phobos, and you get 2595 m/s of delta-v. That's quite a lot if you ask me.

...not really. MAVEN, by my calculations, had ~2,400 m/s of delta-V at launch. Most deep-space probes have around the same amount of delta-V (2-2.5 km/s), so to achieve the kind of delta-V you want, you would probably just need a hypergolic or monopropellant fueled stage or tug (like the modified Fregat on Phobos-Grunt) to give you some capability and you should be fine.

Actually, delta-V capability is one of the reasons VESPA isn't the baseline spacecraft in that illustration anymore.

 

[Nicholander]

Not exactly 2,400 m/s, according to BrianJ's mod, it's 2,050 m/s. Not to be rude or anything, but I think that was mostly because that MAVEN had a low dry mass.

 

[ISProgram]

But, for the sake of comparison, how much mass does Galileo II's RTGs have, and how much would solar panels that generate the same amount of power at Mars' distance weigh?

If it helps, the RTG that Cassini, Ulysses, and New Horizons use/used is called the GPHS-RTG, and it weighs 56 kg per unit (forget if that's fueled or unfueled, probably the former).

Not sure how much power it produces either.

 

[Nicholander]

It produces 300 watts when it's fueled, according to the page. But that's just one by itself. Also, K_Jameson, what would be a good estimate for the dry mass of PADSL? (The configuration with jettisoned drop tanks, not multistageing)

 

[ISProgram]

Well, according to Spaceflight 101, MAVEN has a dry mass of 809 kg and a mass of 2,454 kg at launch. to me, this translate to roughly 1,645 kg of fuel.

MAVEN is powered by six MR-107N engines (same as baselined VESPA, if you look carefully ), which have an Isp ranging from 229 to 232 seconds. They run on hydrazine monoprop, so that makes sense.

Now I use this delta-V calculator, I consider it reliable. if you input the values mentioned earlier (dry mass 809, full mass 2454, Isp 229), you get 2492.02 m/s of delta-V capability. Going with the higher Isp number (232 seconds), you get 2,524.62 m/s of delta-V.

This is how I calculated the delta-V capability, but there is a lot of uncertainty with the actual numbers...like the fact that MAVEN also has ACS thrusters with yet another different Isp number, etc.

---------- Post added at 06:35 PM ---------- Previous post was at 06:34 PM ----------

It produces 300 watts when it's fueled, according to the page.

...I linked the page but didn't even read it. :facepalm:

 

[Nicholander]

Hmm, okay. But I would like to tell you that it's payload mass (Science stuff) was only 65 kg, compared to its dry mass of 809 kg. Also, I'm trying to figure out which launch vehicle I should use with this calculator.

 

[ISProgram]

Hmm, okay. But I would like to tell you that it's payload mass (Science stuff) was only 65 kg, compared to its dry mass of 809 kg. Also, I'm trying to figure out which launch vehicle I should use with this calculator.

All spacecraft have a tiny payload mass, at least when compared to their full mass. So not surprised at all with that.

Silverbird. Very compatible with Trajectory Browser. What exactly are you trying to figure out?

You mentioned using either the M-II or Jarvis. I would use the Jarvis (no offense Pipcard!) because it (probably) has a higher margin for error with its payload.

But what I don't think you should do (with confidence, at least) is use Trajectory Browser to try to figure out the rocket you should use. Browser can have a big discrepancy between what IT says and what Orbiter says. Orbiter is a hellavu lot more realistic, there is normally a ~10% discrepancy between these two resources.

 

[Nicholander]

Well, I've sort of selected the Jarvis C, but if the final mass of the spacecraft is low enough, I'll go with the Neptune 1B with a Fregat. The Neptune 1B with a Fregat can get about 3.9 tonnes to the TMI transfer orbit, while the Jarvis C can get about 15 tonnes to TMI transfer orbit. Keep in mind though, that I did this without fairing, since I don't know what the fairing masses are and how long it is into the flight that they're jettisoned.

Also, I was trying to do the trajectory I linked to (Launch/TMI on Oct 1 2024), and It's worked quite finely. And Orbital insertion was not 1 km/s, but instead about 630 m/s, though I don't remember it's eccentricity. (Maybe something like 0.9-0.8) I was trying it with the TotalImmersion Descartes, by the way.

 

[TachyonDriver]

If Venus has the VESPA, how about the Low Altitude Mars Base Region Environmental Telemetry Testing Antenna for Mars? LAMBRETTA - it would SCOOT around its orbit collecting the required data.

AHEM! Sorry, just had to think of a humorous counter to the VESPA acronym. Back to the serious mission planning.

 

[ISProgram]

If Venus has the VESPA, how about the Low Altitude Mars Base Region Environmental Telemetry Testing Antenna for Mars? LAMBRETTA - it would SCOOT around its orbit collecting the required data.

AHEM! Sorry, just had to think of a humorous counter to the VESPA acronym. Back to the serious mission planning.

The next Venus mission is called VERACRUZ (Venus Environment Radar Aperture...etc.). :thumbup:

Officially, the next Mars orbiter in planning is called MITO (Mars Interim Telecommunication Orbiter), since Mars needs an internet right now, if you know what I mean...

I WAS going to call it MIKU at one point, but...what could 'K' stand for?

 

[Nicholander]

Okay, I really don't think acronym names are really important right now. Let's get back to PADSL.

 

[ISProgram]

Oh, I used Silverbird to calculate the Jarvis C's payload capacity.

With the GTO upper stage, it gets about 24,775 kg to a 185 km x 185 km x 28.7 orbit. That's much less than the 34,100 kg listed in the Jarvis manual, so Silverbird is best used for preliminary LV performance calculations.

What exactly did you put in for your measurements? It would appear the Jarvis will have a lot of extra performance, even without the fairings.

Also: this is the Browser page I'm using for my Mars launch opportunities. It might be of help.

 

[Nicholander]

This is what I entered for the Jarvis C:

 

[K_Jameson]

The Neptune 1B with a Fregat can get about 3.9 tonnes to the TMI transfer orbit, while the Jarvis C can get about 15 tonnes to TMI transfer orbit.

Actually, the correct figure for Jarvis C is about 9.8/10 tonnes.

 

[Nicholander]

Oh. How did you figure that out, by the way? And what about for a Neptune-1B with a Fregat?

Also, K_Jameson, would it be better to have PADSL use jettisonable side tanks rather than multistaging? I think that would avoid the need for having 3 different engines and the sub-systems that they require.

 

[ISProgram]

Now it's 48,023 kg (from Cape Carnaveral), which is too high.

If my math is correct, that's a 34% increase over what it does in Orbiter, for any of your subsequent calculations, you should take out that same proportion of excess payload capability. That should approximate how much Jarvis can do for that given orbit in Orbiter.

Do you have a model of PADSL? I probably don't have programs that can open it (only SketchUp and Anim8or), but if you could obtain viable dimensions for it, we can start calculating dry mass, fuel mass, etc.

It might be wise to baseline what the spacecraft will look like:

Phobos-Grunt would've performed similar to PADSL; the lander (and the microprobe) could be excluded, and a Hayabusa/OSIRIS-REx-type orbiter place in its stead. This would be similar to its planned sequel, with the lander switched out.

It might look like this, without the Beagle 2 on top:

 

[K_Jameson]

Oh, I used Silverbird to calculate the Jarvis C's payload capacity.

With the GTO upper stage, it gets about 24,775 kg to a 185 km x 185 km x 28.7 orbit. That's much less than the 34,100 kg listed in the Jarvis manual, so Silverbird is best used for preliminary LV performance calculations.

What exactly did you put in for your measurements? It would appear the Jarvis will have a lot of extra performance, even without the fairings.

Two things. First: if I remember correctly, Jarvis C - DLL version has a bug in Orbiter because the dll was coded with a wrong value for the thrust of the third stage (exaggerated ten times). I haven't the source code, so I can't correct the problem. The ordinary multistage version, that is the one in which I was personally involved, has no problem.

Second: the 34,100 LEO value is untested in Orbiter because Jarvis C was never meant for LEO service, but only for GTO/GEO/lunar/interplanetary missions. The third stage has too weak thrust for the theoretical LEO payload of over 34 tonnes, and the gravity losses are huge. Jarvis L is perfectly suited for LEO service. If you want something bigger, move on Jarvis B (LEO only again) or Jarvis E (all type of missions).

 

[Nicholander]

I don't have a 3D model yet, sadly. I also use 3D wings, which can export to .3DS, which Anim8or can import. And I don't think It'll look much like Phobos-Grunt or Phobos-Grunt 2, It'll look more like Efesto than anything else. (Though, I haven't started modelling it, so I'm not completely sure)

Also, please could you answer my questions in my post above, K_Jameson?

EDIT: So, if there's that problem in the DLL version of the Jarvis C, are you going to use the Multistage or DLL version to launch Shakespeare/Pope?

 

[Pipcard]

The next Venus mission is called VERACRUZ (Venus Environment Radar Aperture...etc.). :thumbup:

Officially, the next Mars orbiter in planning is called MITO (Mars Interim Telecommunication Orbiter), since Mars needs an internet right now, if you know what I mean...

I WAS going to call it MIKU at one point, but...what could 'K' stand for?

Kommunications? Nah, that only belongs in Kerbal Space Program.

If I were to create HASDA's Mars probe, it might be called "Negai" (because Japan's is called "Nozomi" which pretty much means the same thing, "wish"). Although there already is a real-life spacecraft called Negai, but it's a cubesat.

Another one might be called [ame="http://en.wikipedia.org/wiki/MELOS"]Mars Exploration with a Lander-Orbiter DYnamic[/ame].