Project Lyra

[Ozzallos]

Since the section is labelled "Challenges and Mission Ideas" I thought this would be the most appropriate place to post this. We have asteroid encounters in place, but let's up the ante.

Asteroid 1I/2017 U1 Oumuamua is shaping up to be the first interstellar asteroid encountered by humanity. The most important attribute beyond its interstellar origins is the fact that it is fast, possessing a eccentricity of 1.2 and is currently on its way out of our solar system at 26km/s. Nothing we've built so far has ever reached that speed and an intercept this late in the game would need to get started within the next few years IRL. Project Lyra was commissioned to study that proposal, but something tells me we can do better. One wonders if a somebody or group of somebodies or perhaps even Squad themselves can develop an Oumuamua encounter vaguely based on the Lyra premise. I would like to contribute but sadly do not have the modding skills or time to even consider it, so broaching the idea here will have to do. Of course, there are challenges to consider, mainly in that KSP isn't a 1:1 solar simulator. Tech realism isn't so much of an issue, but it is a consideration. In either case the basic path and composition of the asteroid are known quantities, so pluses and minuses.

If this belongs somewhere else, definitely feel free to move it. Regardless, it would be fun to see this real life event gain some traction in KSP.

 

Edited December 20, 2017 by Ozzallos
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[sevenperforce]

Flying expendable, Falcon Heavy can send 3.5 tonnes to a Pluto Hohmann transfer, which is 390 m/s short of solar escape with a hyperbolic excess velocity of zero.

Oumuamua is trucking along with a hyperbolic excess velocity of 26 km/s.

So if you can fit more than 26.39 km/s of dV into a 3.5-tonne package on Falcon Heavy, you can catch up to Oumuamua.

At launch, the Dawn spacecraft packed three ion thrusters and 425 kg of xenon with a dry mass of 792.7 kg, for a total of about 10 km/s of dV (avg isp = 2000 seconds). Let's suppose we add 2.28 tonnes of xenon (ignoring tankage mass, as that dry mass can probably be reduced since we don't need all the same things Dawn has), bringing total mass up to 3.5 tonnes.

With the same average isp, that gives us 30.8 km/s of dV. Not an early catch, but a catch. We can improve that if we strip down the mass of our spacecraft a bit. New Horizons had a dry mass of only 401 kg; optimistically, this would give us a whopping 42.6 km/s of dV.

Very doable.

[DoctorDavinci]

5 hours ago, sevenperforce said:

Flying expendable, Falcon Heavy can send 3.5 tonnes to a Pluto Hohmann transfer, which is 390 m/s short of solar escape with a hyperbolic excess velocity of zero.

Oumuamua is trucking along with a hyperbolic excess velocity of 26 km/s.

So if you can fit more than 26.39 km/s of dV into a 3.5-tonne package on Falcon Heavy, you can catch up to Oumuamua.

At launch, the Dawn spacecraft packed three ion thrusters and 425 kg of xenon with a dry mass of 792.7 kg, for a total of about 10 km/s of dV (avg isp = 2000 seconds). Let's suppose we add 2.28 tonnes of xenon (ignoring tankage mass, as that dry mass can probably be reduced since we don't need all the same things Dawn has), bringing total mass up to 3.5 tonnes.

With the same average isp, that gives us 30.8 km/s of dV. Not an early catch, but a catch. We can improve that if we strip down the mass of our spacecraft a bit. New Horizons had a dry mass of only 401 kg; optimistically, this would give us a whopping 42.6 km/s of dV.

Very doable.

Looks good on paper but can you show us within the kerbal scale how you would go about it

I am really interested in seeing a demonstration of your calculations within KSP 

[Vanamonde]

Since you're suggesting this be added to the game, your thread has been moved to Suggestions.  

[Corona688]

With something screaming by at 25km/s, I don't think a "fast catch" is practical, but a slow catch can be done.

You can get 25km/s delta-v on a two-stage ion probe.  It would carry 10,500 units of xenon, and have a dry weight of 1.2 tons.  One tank would be ejected midway. Assuming most of the burn happens near enough to the sun for full power, it can accomplish the entire burn in 6 hours realtime, 1.5 hours physwarp.  Another 9,700m/s would be added with a 30-ton nuclear engine stage.

So:  Surprisingly doable.  Communication will be a problem, leave relays on every stage you drop.  Slowing down may be slower than speeding up, out where sunlight can't be relied on.