Could the soon to be launched Falcon Heavy be aimed at Oumuamua

[whitelancer64]

I knew and understand this. What I meant in this context is: Why would one be able to keep a satellite in storage waiting for a mission and not a deep space probe?

You could. You'd just need to refurbish it before it could fly.

[rakaydos]

With a Falcon Heavy rocket due to be launched and no important mission for it planned (other than car delivery to Mars), would it be possible to grab the opportunity and aim to catch up with , film and gather as much information  on the Oumuamua, inter-stellar asteroid that recently passed Earth.

It is probably just a lump of rock but as its 1:10 shape and high rotation rate make it appear an interesting object, apart from it origin probably being from another star.

There are probably no other rockets planned to be launched soon that could undertake this task.

I also feel that we should have probes ready to be launched at short notice , if an event like this occurs again.

No way. Somebody did the math: https://www.centauri-dreams.org/?p=38728

One potential mission architecture is to make use of SpaceX’s Big Falcon Rocket (BFR) and their in-space refueling technique with a launch date in 2025. To achieve the required hyperbolic excess (at least 30 km/s) a Jupiter flyby combined with a close solar flyby (down to 3 solar radii), nicknamed “solar fryby” is envisioned.

Trajectory simulation provided:

[the_other_Doug]

Unfortunately, when you copy in an XKCD comic, you lose the mouseover text.  In this case, that text was something along the lines of "Besides, we're strictly an Orbiter shop, here."

[mikelepage]

Relinking this from earlier in the thread:
https://www.centauri-dreams.org/?p=38728

Combining all those ideas, it sounds to me like the only (remotely) feasible plan would be:
1) to use (refuelled) cargo BFR to launch probe towards Jupiter, for gravity assist (launch window in 2025).
2) perform "solar fry-by" Oberth boost at distance current thermal technologies can handle:
         - calculated that "fry by" at 3 solar radii would give sufficient kick to achieve rendezvous by itself.
         - perhaps "fry by" is possible with current tech at 30 or 300 solar radii (how close can we go safely?).
         - (I'm picturing a Pica-X coated fairing structure that will jettison after solar encounter)
3) Deploy solar sail technology to make up the difference in delta-V.

EDIT: This probe is going to 8.6 solar radii.
https://www.livescience.com/58023-can-spacecraft-fly-to-the-sun.html

[speedevil]

w in 2025).
2) perform "solar fry-by" Oberth boost at distance current thermal technologies can handle:
         - calculated that "fry by" at 3 solar radii would give sufficient kick to achieve rendezvous by itself.
         - perhaps "fry by" is possible with current tech at 30 or 300 solar radii (how close can we go safely?).

In short - no.
To get any meaningful benefit for this mission, it needs to be very, very close to the sun.
The technology in principle isn't very complicated, it's just that you need many layers of vacuum spaced insulation, which works when the top layer is at ~3500C.
This would be something like a tungsten tile outer shield, with one shiny and one treated side, with niobium foil,, backed up with several layers of spaced stainless until  you get to conventional aluminium/high temperature plastic.
This is not going to be easy to develop.

[sanman]

It’s a cute coincidence, the first interstellar asteroid flying by the first Heavy being assembled. But that’s as close as they get.

Maybe the aliens have been watching SpaceX capabilities progress and decided it was time to take a closer look at this planet. 

[mikelepage]

w in 2025).
2) perform "solar fry-by" Oberth boost at distance current thermal technologies can handle:
         - calculated that "fry by" at 3 solar radii would give sufficient kick to achieve rendezvous by itself.
         - perhaps "fry by" is possible with current tech at 30 or 300 solar radii (how close can we go safely?).
3) Deploy solar sail technology to make up the difference in delta-V.*

In short - no.
To get any meaningful benefit for this mission, it needs to be very, very close to the sun.

*Firstly I've added point 3 back into the quote.  Even a "lightsail" style (32m²) solar sail could add a decent dV to a New Horizon's sized probe.

But I guess I'm confused by your answer.  I've always understood the size of the Oberth effect to be proportional to the velocity of the spacecraft when the burn is made (at perihelion in this instance).  In order to get to the "fry-by"  transfer orbit in the first place you've given your spacecraft a Jupiter gravity assist, so the semi-major axis of that transfer orbit has to be about 2.6 AU.  Given this large semi-major axis, how big a difference does a perihelion distance is 0.014 AU (3 solar radii), versus 0.14 AU (30 solar radii), really make? especially when it can make such a difference to the mass/complexity of your shielding apparatus?

[Pete]

But I guess I'm confused by your answer.  I've always understood the size of the Oberth effect to be proportional to the velocity of the spacecraft when the burn is made (at perihelion in this instance).  In order to get to the "fry-by"  transfer orbit in the first place you've given your spacecraft a Jupiter gravity assist, so the semi-major axis of that transfer orbit has to be about 2.6 AU.  Given this large semi-major axis, how big a difference does a perihelion distance is 0.014 AU (3 solar radii), versus 0.14 AU (30 solar radii), really make? especially when it can make such a difference to the mass/complexity of your shielding apparatus?

The difference in velocity at perihelion between those two orbits is very small(*), less than TWO HUNDRED AND FORTY kilometers per second difference.

_{(*) Just in case it is not obvious, at this point the Sarcasm meter is maxed out}

[Asteroza]

Wonder if you could run a solar thermal propulsion rig of sorts during the fryby, using a propellant cooled sunshield as a propellant boiler for a deep solar oberth maneuver?

[mikelepage]

But I guess I'm confused by your answer.  I've always understood the size of the Oberth effect to be proportional to the velocity of the spacecraft when the burn is made (at perihelion in this instance).  In order to get to the "fry-by"  transfer orbit in the first place you've given your spacecraft a Jupiter gravity assist, so the semi-major axis of that transfer orbit has to be about 2.6 AU.  Given this large semi-major axis, how big a difference does a perihelion distance is 0.014 AU (3 solar radii), versus 0.14 AU (30 solar radii), really make? especially when it can make such a difference to the mass/complexity of your shielding apparatus?

The difference in velocity at perihelion between those two orbits is very small(*), less than TWO HUNDRED AND FORTY kilometers per second difference.

_{(*) Just in case it is not obvious, at this point the Sarcasm meter is maxed out}

Okay.  Thanks for showing your working.*
_{(*)Still maxed out}

For anyone else who actually wants to learn something on this forum without being snarked at, the correct formula to use is as follows:

V= (2GM/r - GM/a)^0.5
where:
r is the current altitude of the craft above the sun, and
a is the semi major axis.

So for a=2.6 (coming from Jupiter gravity assist):
where r is 3 solar radii, V=356km/s
where r is 10 solar radii V=194km/s
where r is 30 solar radii, V= 111km/s

[speedevil]

Wonder if you could run a solar thermal propulsion rig of sorts during the fryby, using a propellant cooled sunshield as a propellant boiler for a deep solar oberth maneuver?

In principle, yes.
Liquid hydrogen, pumped through coolant channels might get quite decent ISP.
But, liquid hydrogen is an extreme pain to keep liquid on the way to the sun, it needs to get quite hot indeed, and the heat exchanger is untried technology that needs to be lightweight, large in area, and work at ~2000C and a thousand PSI without leaking.
And you're still 'only' looking at an ISP of ~1000 or so, which you can effectively get with an extra solid stage.

[Pete]

Okay.  Thanks for showing your working.*
_{(*)Still maxed out}

For anyone else who actually wants to learn something on this forum without being snarked at...

It's hard to judge how much detail to include..
One would expect anyone that quotes Oberth effect, to have a very fundamental understanding of orbital dynamics. At least to the extent of knowing that an orbit at 1/10th the height will be a LOT faster.
This is so true that I initially thought the OP was trolling with his comment of "how big a difference does a perihelion distance is 0.014 AU (3 solar radii), versus 0.14 AU (30 solar radii), really make?", as this comment is in the same class as an airplane enthusiast asking "so why is a f14 faster than a Cessna?".
Doubly so as he also states "or 300 solar radii (how close can we go safely?"
Considering the Earth orbits the sun at a mere 260 sol radii, this is a very, very stupid comment to make.


One presupposes that he actually knows the answer and is being sarcastic/trolling in asking that.

In light of this perceived joking mood I found my reply, including the very tongue-in-cheek comment, to be quite appropriate.

[Pete]

Small P.S.
One may ask why they have selected 3 solar radii as the 'fryby' distance, rather than anything closer.
After all, the sun would already extend over a very large part of the sky, total radiative flux would not increase that much as you get closer.

The simple answer is: at the ludicrous speeds one would be moving at that distance, the solar corona might as well be a solid brick wall. As it extends as a significant presence to about 2.6 radii, and is *highly* variable, even 3 radii is taking a big chance of running into something measurable enough to do damage.

And no, I don't think we have the technology to build anything that can survive at 3 solar radii, except as a passive and heavily-shielded package.
Having to put an active probe there, including supplying it with a few dozen km/s of delta-v ability, is way beyond us.
Remember, that it would have minutes to scant hours only to utilize the full benefit of the close flyby. This precludes all of the efficient high-ISP propulsion methods we normally would use, such as ion drives.
The only thing we have that is in the right ballpark would be Orion (bang-bang, not sts), or a solar-thermal as mentioned in a post above.
While both of these are conceptually possible, we are a very,very long way from having working designs for them, in the sort of environment where they would be needed.

[envy887]

But I guess I'm confused by your answer.  I've always understood the size of the Oberth effect to be proportional to the velocity of the spacecraft when the burn is made (at perihelion in this instance).  In order to get to the "fry-by"  transfer orbit in the first place you've given your spacecraft a Jupiter gravity assist, so the semi-major axis of that transfer orbit has to be about 2.6 AU.  Given this large semi-major axis, how big a difference does a perihelion distance is 0.014 AU (3 solar radii), versus 0.14 AU (30 solar radii), really make? especially when it can make such a difference to the mass/complexity of your shielding apparatus?

The difference in velocity at perihelion between those two orbits is very small(*), less than TWO HUNDRED AND FORTY kilometers per second difference.

_{(*) Just in case it is not obvious, at this point the Sarcasm meter is maxed out}

Okay.  Thanks for showing your working.*
_{(*)Still maxed out}

For anyone else who actually wants to learn something on this forum without being snarked at, the correct formula to use is as follows:

V= (2GM/r - GM/a)^0.5
where:
r is the current altitude of the craft above the sun, and
a is the semi major axis.

So for a=2.6 (coming from Jupiter gravity assist):
where r is 3 solar radii, V=356km/s
where r is 10 solar radii V=194km/s
where r is 30 solar radii, V= 111km/s

A larger semi-major axis also increases the fry-by velocity. Using Jupiter to not only change direction but also increase speed, the semi-major axis coming out of the gravity assist could be much larger than 2.6 AU.

[speedevil]

And no, I don't think we have the technology to build anything that can survive at 3 solar radii, except as a passive and heavily-shielded package.
Having to put an active probe there, including supplying it with a few dozen km/s of delta-v ability, is way beyond us.

It doesn't need dozens of km/s (unless you want to rendezvous with the comet).

If we are considering the boost in velocity you get at infinity from a craft falling from infinity, by burning instantaneously at the closest point to the sun, then at three solar radii, with a velocity of 350km/s, a 3.5km/s burn from a solid rocket will get you a factor of ((from wikipedia) , or sqrt(700/3.5) *3.5 = 50km/s excess at infinity.

It's not this good, as this is if you are not trying to modify the trajectory at all, for a jupiter assist this limits you to a very small portion of the sky.
Also, the above calculation is for a parabolic orbit, not a hyperbolic one which a jupiter assist to the sun would get you.

Heat shielding is a really annoying problem, the heat shield on Solar Probe (2005) hit 1900C at 4 solar radii. (solar probe plus is the more recent one going to 8.5 radii that looks like it may launch.

is an image of thermal simulations when hot. Note that's C, not K.
From this study of the now cancelled probe.

The design is 'easy' in principle - you have a cone pointing down towards the sun, which lets it come to a rather lower equilibrium temperature than it might otherwise, as the light is both somewhat reflected by coatings, and only limited exposure to the sun.
Thermal insulators to the back of this shield, which operates at ~400C or so, and radiates the solar gain to space.
And the probe (with the underneath of it very reflective) on non-conductive standoffs within the cone of shadow.

At 3.5 radii, this 'just' gets a little worse.

The design would look something like the above cone, then a stage like the spherical Star 48 solid rocket on top, with a carbon fibre truss out the top to act as a counterweight during thrust.

The mechanical design gets rather harder, as it's got to take several G sideways, with vibration.

There is nothing beyond the laws of physics for even fairly modest solid rockets to do this.
It's just deeply nasty engineering.

[Zed_Noir]

A more relevant question is the Delta-V required to intercept Oumuamua? For a launch in 2020.

[speedevil]

A more relevant question is the Delta-V required to intercept Oumuamua? For a launch in 2020.

Considering direct launch.

From a blog version of the recent paper.

It can be seen that a minimum 𝐶3 exists, which is about 26.5 km/s (703km˛/s˛). However, this minimum value rapidly increases when the launch date is moved into the future. At the same time, a larger mission duration leads to a decrease of the required 𝐶3 but also implies an encounter with the asteroid at a larger distance from the Sun. A realistic launch date for a probe would be at least 10 years in the future (2027). At that point, the hyperbolic excess velocity is already at 37.4km/s (1400km˛/s˛) with a mission duration of about 15 years, which makes such an orbital insertion extremely challenging with conventional launches in the absence of a planetary fly-by.

So, at the moment, about 30km/s from LEO.
Falcon heavy launching one of the centre stages, and then being  fully refuelled in LEO,, with a falcon 1 as payload.
(there are issues, which I will neglect)

This may with a following wind get you to 20km/s, and a ton payload, being generous.
That ton payload being three stages of solid rockets might get five kilos to 30km/s - being optimistic.
I am sure you can do a probe that will return some data weighing 5kg and flying by the asteroid at ~10km/s - that this is not precluded by the laws of physics.

But, you're going to need a tiny RTG of some form, and novel optical comms, and you're not going to get much data on a rapid poorly targetted flyby in badly lit conditions.

The above is the sort of thing you can almost justify by handwaving if you avoid looking really hard at any of it.
In reality, you're going to need to put very considerably more thought into this, and it's probably going to either end up as being a large RTG/reactor craft with a big ion engine on the biggest launcher you can find, or something actually preplanned and put in place in advance.

For example, a couple of new horizons type craft hanging around near Jupiter with the ability to use a relatively small kick motor to fall past Jupiter on one side or the other and get quite a large controllable delta-v to have a decent chance of meeting objects like this, combined with a survey network to find them a year before, not a year after apoapsis.

If the question was if we could launch it to intercept the same asteroid if it had its closest appoach next, not last September, the question would be a straightforward yes. (in comparison to the exotic hoops we have to jump through to catch it now)

[Patchouli]

Too bad JIMO was canned as the propulsion technology from it could be used to catch Oumuamua.
I wonder how far did the SAFE-400 get along and could at least the Safe 30 design be brought back into production.

Though another option might be to send a small probe powered by a RTG and use a Caster-30 and a Star-48 as the third and forth stages.

It would already be exiting the solar system very quickly so I'm not sure how much delta V could be added by making use of solar electric propulsion or a solar sail but it might be worth adding.

[Zed_Noir]

A more relevant question is the Delta-V required to intercept Oumuamua? For a launch in 2020.

Considering direct launch.

From a blog version of the recent paper.

It can be seen that a minimum 𝐶3 exists, which is about 26.5 km/s (703km˛/s˛). However, this minimum value rapidly increases when the launch date is moved into the future. At the same time, a larger mission duration leads to a decrease of the required 𝐶3 but also implies an encounter with the asteroid at a larger distance from the Sun. A realistic launch date for a probe would be at least 10 years in the future (2027). At that point, the hyperbolic excess velocity is already at 37.4km/s (1400km˛/s˛) with a mission duration of about 15 years, which makes such an orbital insertion extremely challenging with conventional launches in the absence of a planetary fly-by.

So, at the moment, about 30km/s from LEO.
Falcon heavy launching one of the centre stages, and then being  fully refuelled in LEO,, with a falcon 1 as payload.
(there are issues, which I will neglect)

This may with a following wind get you to 20km/s, and a ton payload, being generous.
That ton payload being three stages of solid rockets might get five kilos to 30km/s - being optimistic.
I am sure you can do a probe that will return some data weighing 5kg and flying by the asteroid at ~10km/s - that this is not precluded by the laws of physics.

But, you're going to need a tiny RTG of some form, and novel optical comms, and you're not going to get much data on a rapid poorly targetted flyby in badly lit conditions.

The above is the sort of thing you can almost justify by handwaving if you avoid looking really hard at any of it.
In reality, you're going to need to put very considerably more thought into this, and it's probably going to either end up as being a large RTG/reactor craft with a big ion engine on the biggest launcher you can find, or something actually preplanned and put in place in advance.
<snip>

Just to be clear. The OP's idea of using the Falcon Heavy demo test flight to intercept Oumuamua seem not feasible.

However as an alternate flight architecture to the one outline by @speedevil.

Put a single engine Centaur on top a complete Falcon Heavy stack enclosed in a RUAG PLF. Launch the Falcon Heavy in the fully expendable mode. Use the Centaur as the Earth Departure stage for a probe similar in mass to the New Horizon spacecraft. Assuming a gravity assist at Jupiter. The probe itself will have a MMRTG power source charging batteries for high power radio transmissions, since the MMRTG only output about 100W electrical power.

Would the probe have enough Delta-V to intercept Oumuamua?

[ThereIWas3]

Gravity assistance from Jupiter is useful if you want to accelerate in the plane of the planets.  I am not sure it is useful in this case where IIRC Oumuamua's path is inclined at 60°.