Here’s the path of ʻOumuamua as it passed through the solar system about a year ago. At its fastest it was travelling around 320000 km/h. 15 months after perihelion, it is already further from the Sun than Saturn is.

I wondered what the fastest celestial object ever observed in the solar system was (heliocentric speed): it’s probably Comet Lovejoy, which was moving at over 2 million km/h at perihelion, or Great Comet of 1843 which was going a similar speed.

The two unusual things about ʻOumuamua were:
1/ It’s strongly hyperbolic orbit, indicating an origin outside the solar system. The maths indicate that this can’t be something that was in the Oort cloud that was perturbed or anything like that. It came from somewhere else (maybe the dwarf star HIP 3757), and it came in fast: it was pegging at about 95000 km/h before it even reached the solar system and it will leave at the same speed.

2/ Based on its light curve, it is either elongated like a pen (about a 10:1 length:width ratio), or it is extremely flat and thin like a pancake.

It is a bit reddish but that’s not uncommon. Probably tholins. Or racing stripes.

So one other thing I was wondering was: could NASA build something to run a flyby of it?

It would be a big ask for a couple of reasons. 1/ It is moving ridiculously fast. It will be past the orbit of Pluto by 2023. And to catch it, the spacecraft has to be going faster than that. 2/ Because of its location, a Jupiter gravity assist is not an option. So all of the speed is going to have to come from rocketry.
So, working backwards from the objective, how much rocketry is that? Does NASA have that much rocketry? Is it all the rocketry?

Suppose the craft had the specs of the New Horizons craft. Because of signal strength issues we would want the encounter to be within 60 AU of the sun. That means the encounter has to happen by 2027. NASA already has some spare parts for the NH, and they have the design obviously: let’s say they got it manufactured, assembled and tested within a year from now so that it had 7 years to get to specific location 60 AU away.

Timing it to take maximum advantage of the Earth’s orbital speed, you’re still going to need, best case scenario, 21 km/s of delta-V from LEO.

None of the off-the-shelf hardware is well tuned to this task, but you could actually do it using SpaceX’s Falcon Heavy. It would have to launch straight to interplanetary trajectory, no messing about with an intermediate LEO phase, so yeah you’d want to be pretty sure of your guidance. Also it would mean using the non-environmentally friendly “zero reused” configuration and also it would make Elon Musk richer.

Why bother?

Bubblecar said:

Why bother?

it is science. Why ask?

roughbarked said:

Bubblecar said:

Why bother?

it is science. Why ask?

It may be science but it would require a fairly extreme effort that doesn’t seem to be justified given that it’s just going to be another funny-shaped asteroidy thing.

Bubblecar said:

roughbarked said:

Bubblecar said:

Why bother?

it is science. Why ask?

It may be science but it would require a fairly extreme effort that doesn’t seem to be justified given that it’s just going to be another funny-shaped asteroidy thing.

And what else would astronomy be without lens grinders?

Bubblecar said:

Why bother?

A fair and reasonable question and I’m not especially advocating such a mission, just checking whether it is possible.

Reasons in favour would be that this is the first object from another solar system that we’ve had the chance to investigate. Maybe it is fundamentally different from the bodies in this solar system in some way. Maybe the red is something other than tholins, maybe the isotope ratios will be instructive. Maybe there won’t be another opportunity to get a look at something from another solar system for hundreds or thousands of years.

On the “agin” side, it might not be that amazing, it’s only small, it would be a pacy flyby, the thing is so small and the flyby is so distant that there’s a worse than average chance of messing up the encounter, and the extra rocketry and rush would mean that the mission would likely cost about twice as much as a New Horizons type mission. NASA could check out two major Kuiper Belt bodies for that money, or have a tidy mission to Neptune or Uranus.

dv said:

Bubblecar said:

Why bother?

A fair and reasonable question and I’m not especially advocating such a mission, just checking whether it is possible.

Reasons in favour would be that this is the first object from another solar system that we’ve had the chance to investigate. Maybe it is fundamentally different from the bodies in this solar system in some way. Maybe the red is something other than tholins, maybe the isotope ratios will be instructive. Maybe there won’t be another opportunity to get a look at something from another solar system for hundreds or thousands of years.

On the “agin” side, it might not be that amazing, it’s only small, it would be a pacy flyby, the thing is so small and the flyby is so distant that there’s a worse than average chance of messing up the encounter, and the extra rocketry and rush would mean that the mission would likely cost about twice as much as a New Horizons type mission. NASA could check out two major Kuiper Belt bodies for that money, or have a tidy mission to Neptune or Uranus.

Also, you’re the only one suggesting it AFAIA, and nobody from NASA posts here.

Bubblecar said:

dv said:

Bubblecar said:

Why bother?

A fair and reasonable question and I’m not especially advocating such a mission, just checking whether it is possible.

Reasons in favour would be that this is the first object from another solar system that we’ve had the chance to investigate. Maybe it is fundamentally different from the bodies in this solar system in some way. Maybe the red is something other than tholins, maybe the isotope ratios will be instructive. Maybe there won’t be another opportunity to get a look at something from another solar system for hundreds or thousands of years.

On the “agin” side, it might not be that amazing, it’s only small, it would be a pacy flyby, the thing is so small and the flyby is so distant that there’s a worse than average chance of messing up the encounter, and the extra rocketry and rush would mean that the mission would likely cost about twice as much as a New Horizons type mission. NASA could check out two major Kuiper Belt bodies for that money, or have a tidy mission to Neptune or Uranus.

Also, you’re the only one suggesting it AFAIA, and nobody from NASA posts here.

B.C. posts here…

Bubblecar said:

dv said:

Bubblecar said:

Why bother?

A fair and reasonable question and I’m not especially advocating such a mission, just checking whether it is possible.

Reasons in favour would be that this is the first object from another solar system that we’ve had the chance to investigate. Maybe it is fundamentally different from the bodies in this solar system in some way. Maybe the red is something other than tholins, maybe the isotope ratios will be instructive. Maybe there won’t be another opportunity to get a look at something from another solar system for hundreds or thousands of years.

On the “agin” side, it might not be that amazing, it’s only small, it would be a pacy flyby, the thing is so small and the flyby is so distant that there’s a worse than average chance of messing up the encounter, and the extra rocketry and rush would mean that the mission would likely cost about twice as much as a New Horizons type mission. NASA could check out two major Kuiper Belt bodies for that money, or have a tidy mission to Neptune or Uranus.

Also, you’re the only one suggesting it AFAIA, and nobody from NASA posts here.

:) As could be envisaged, dv would have to make the suggestion to them and possibly call in that bloke with the muskiness for funding.

ChrispenEvan said:

Bubblecar said:

dv said:

A fair and reasonable question and I’m not especially advocating such a mission, just checking whether it is possible.

Reasons in favour would be that this is the first object from another solar system that we’ve had the chance to investigate. Maybe it is fundamentally different from the bodies in this solar system in some way. Maybe the red is something other than tholins, maybe the isotope ratios will be instructive. Maybe there won’t be another opportunity to get a look at something from another solar system for hundreds or thousands of years.

On the “agin” side, it might not be that amazing, it’s only small, it would be a pacy flyby, the thing is so small and the flyby is so distant that there’s a worse than average chance of messing up the encounter, and the extra rocketry and rush would mean that the mission would likely cost about twice as much as a New Horizons type mission. NASA could check out two major Kuiper Belt bodies for that money, or have a tidy mission to Neptune or Uranus.

Also, you’re the only one suggesting it AFAIA, and nobody from NASA posts here.

B.C. posts here…

But do we know for sure?

ChrispenEvan said:

B.C. posts here…

Thankfully not any more.

It might have been worth trying to send a probe if we’d found out about it a year or three earlier. If I was in charge of such missions I’d have to say no: the cost and risk of doing such a mission would not outweigh the possible benefits.
Just IMHO.

Spiny Norman said:

ChrispenEvan said:

B.C. posts here…

Thankfully not any more.

It might have been worth trying to send a probe if we’d found out about it a year or three earlier. If I was in charge of such missions I’d have to say no: the cost and risk of doing such a mission would not outweigh the possible benefits.
Just IMHO.

I’d think most could only agree, at this point in time.

Bubblecar said:

Also, you’re the only one suggesting it AFAIA, and nobody from NASA posts here.

That’s not intrinsically a point against the mission per se.

Spiny Norman said:

ChrispenEvan said:

B.C. posts here…

Thankfully not any more.

It might have been worth trying to send a probe if we’d found out about it a year or three earlier. If I was in charge of such missions I’d have to say no: the cost and risk of doing such a mission would not outweigh the possible benefits.
Just IMHO.

And a reasonable viewpoint that is.

dv said:

you’re the only one suggesting it AFAIA

And even I am only discussing it in an abstract, lukewarm way.

Probably the best bet for funding it would be to find some gullible wealthy nutter who believes in UFOs.

If we saw it coming would it be of any use if we tried to impact it at speed so as to hopefully create a debris field to study at our leisure?

Apparently others have suggested it, it even has a project name:

Hypothetical space missions
Main article: Project Lyra

ʻOumuamua was at first thought to be traveling too fast for any existing spacecraft to reach. The Initiative for Interstellar Studies (i4is) launched Project Lyra to assess the feasibility of a mission to ʻOumuamua. Several options for sending a spacecraft to ʻOumuamua within a time-frame of 5 to 10 years were suggested. One option is using first a Jupiter flyby followed by a close solar flyby at 3 solar radii (2.1×106 km; 1.3×106 mi) in order to take advantage of the Oberth effect. Different mission durations and their velocity requirements were explored with respect to the launch date, assuming direct impulsive transfer to the intercept trajectory. Using a powered Jupiter flyby, a solar Oberth maneuver and Parker Solar Probe heat shield technology, a Falcon Heavy-class launcher would be able to launch a spacecraft of dozens of kilograms towards 1I/ʻOumuamua, if launched in 2021. More advanced options of using solar, laser electric, and laser sail propulsion, based on Breakthrough Starshot technology, have also been considered. The challenge is to get to the asteroid in a reasonable amount of time (and so at a reasonable distance from Earth), and yet be able to gain useful scientific information. To do this, decelerating the spacecraft at ʻOumuamua would be “highly desirable, due to the minimal science return from a hyper-velocity encounter”. If the investigative craft goes too fast, it would not be able to get into orbit or land on the object and would fly past it. The authors conclude that, although challenging, an encounter mission would be feasible using near-term technology. Seligman and Laughlin adopt a complementary approach to the Lyra study but also conclude that such missions, though challenging to mount, are both feasible and scientifically attractive.

Bubblecar said:

Apparently others have suggested it, it even has a project name:

Hypothetical space missions
Main article: Project Lyra

ʻOumuamua was at first thought to be traveling too fast for any existing spacecraft to reach. The Initiative for Interstellar Studies (i4is) launched Project Lyra to assess the feasibility of a mission to ʻOumuamua. Several options for sending a spacecraft to ʻOumuamua within a time-frame of 5 to 10 years were suggested. One option is using first a Jupiter flyby followed by a close solar flyby at 3 solar radii (2.1×106 km; 1.3×106 mi) in order to take advantage of the Oberth effect. Different mission durations and their velocity requirements were explored with respect to the launch date, assuming direct impulsive transfer to the intercept trajectory. Using a powered Jupiter flyby, a solar Oberth maneuver and Parker Solar Probe heat shield technology, a Falcon Heavy-class launcher would be able to launch a spacecraft of dozens of kilograms towards 1I/ʻOumuamua, if launched in 2021. More advanced options of using solar, laser electric, and laser sail propulsion, based on Breakthrough Starshot technology, have also been considered. The challenge is to get to the asteroid in a reasonable amount of time (and so at a reasonable distance from Earth), and yet be able to gain useful scientific information. To do this, decelerating the spacecraft at ʻOumuamua would be “highly desirable, due to the minimal science return from a hyper-velocity encounter”. If the investigative craft goes too fast, it would not be able to get into orbit or land on the object and would fly past it. The authors conclude that, although challenging, an encounter mission would be feasible using near-term technology. Seligman and Laughlin adopt a complementary approach to the Lyra study but also conclude that such missions, though challenging to mount, are both feasible and scientifically attractive.

https://en.wikipedia.org/wiki/%CA%BBOumuamua#Hypothetical_space_missions

Witty Rejoinder said:

If we saw it coming would it be of any use if we tried to impact it at speed so as to hopefully create a debris field to study at our leisure?

Sure but if we were able to arrange an impact, then we’d be able to do a flyby with a spacecraft…

dv said:

dv said:

you’re the only one suggesting it AFAIA

And even I am only discussing it in an abstract, lukewarm way.

Probably the best bet for funding it would be to find some gullible wealthy nutter who believes in UFOs.

Zarkov?

Bubblecar said:

Apparently others have suggested it, it even has a project name:

Hypothetical space missions
Main article: Project Lyra

Ha.

Lyra? The lyre?
I would have gone with a hunting animal.

dv said:

dv said:

you’re the only one suggesting it AFAIA

And even I am only discussing it in an abstract, lukewarm way.

Probably the best bet for funding it would be to find some gullible wealthy nutter who believes in UFOs.

Yeah, they tend to be enthusiastic about CSOs (Cigar Shaped Objects), which is one interpretation of the light curve.

Bubblecar said:

dv said:

dv said:

you’re the only one suggesting it AFAIA

And even I am only discussing it in an abstract, lukewarm way.

Probably the best bet for funding it would be to find some gullible wealthy nutter who believes in UFOs.

Yeah, they tend to be enthusiastic about CSOs (Cigar Shaped Objects), which is one interpretation of the light curve.

It’s only a polly-waffle.

Witty Rejoinder said:

Bubblecar said:

dv said:

And even I am only discussing it in an abstract, lukewarm way.

Probably the best bet for funding it would be to find some gullible wealthy nutter who believes in UFOs.

Yeah, they tend to be enthusiastic about CSOs (Cigar Shaped Objects), which is one interpretation of the light curve.

It’s only a polly-waffle.

Space cucumber.

Some folks were reminded of Rama from the ACC novel, Rendezvous with Rama. I greatly enjoyed that series.

OTOH Rama rotated about its long axis, creating an internal “artificial gravity” along its inner wall. This thing flips like a ill tossed caber.

dv said:

Some folks were reminded of Rama from the ACC novel, Rendezvous with Rama. I greatly enjoyed that series.

OTOH Rama rotated about its long axis, creating an internal “artificial gravity” along its inner wall. This thing flips like an ill tossed caber.

•fixed.

dv said:

Some folks were reminded of Rama from the ACC novel, Rendezvous with Rama. I greatly enjoyed that series.

OTOH Rama rotated about its long axis, creating an internal “artificial gravity” along its inner wall. This thing flips like a ill tossed caber.

The challenge is to get to the asteroid in a reasonable amount of time (and so at a reasonable distance from Earth), and yet be able to gain useful scientific information. To do this, decelerating the spacecraft at ʻOumuamua would be “highly desirable, due to the minimal science return from a hyper-velocity encounter”. If the investigative craft goes too fast, it would not be able to get into orbit or land on the object and would fly past it.

I think that’s just crazy talk. This means adding more rocketry to the delivered spacecraft so it can effect the 10000 m/s burn to match Oumuamua’s velocity. Bare minimum this means multiplying the mass by 8. These things are multiplicative … it means the launcher needs to be 8 times more powerful. Falcon Heavy is out of the question, you’d be looking at several launches by launchers that don’t yet exist, followed by construction in space. Orbital missions are a huge step up from flybys in terms of launchpad mass … this is why NH was a flyby.
A flyby would be enough to characterise Oumuamua broadly. If it was successful. Would probably fail in all honesty.

dv said:

The challenge is to get to the asteroid in a reasonable amount of time (and so at a reasonable distance from Earth), and yet be able to gain useful scientific information. To do this, decelerating the spacecraft at ʻOumuamua would be “highly desirable, due to the minimal science return from a hyper-velocity encounter”. If the investigative craft goes too fast, it would not be able to get into orbit or land on the object and would fly past it.

I think that’s just crazy talk. This means adding more rocketry to the delivered spacecraft so it can effect the 10000 m/s burn to match Oumuamua’s velocity. Bare minimum this means multiplying the mass by 8. These things are multiplicative … it means the launcher needs to be 8 times more powerful. Falcon Heavy is out of the question, you’d be looking at several launches by launchers that don’t yet exist, followed by construction in space. Orbital missions are a huge step up from flybys in terms of launchpad mass … this is why NH was a flyby.
A flyby would be enough to characterise Oumuamua broadly. If it was successful. Would probably fail in all honesty.

You got there in the end.

Next time

dv said:

Next time

Yeah well, there is always the aspect of forward planning to take into account.

Because of ‘Oumuamua, the IAU added a new category to its provisional naming system. Existing categories non-periodic comets (eg C/2017 O1), P for periodic comets (P/2004 DO29 ), X for comets whose periodicity is not determined, A for asteroids, D for destroyed comets. For ‘Oumuamua they added I for interstellar, and 1I/ʻOumuamua is one of its names.

dv said:

Next time

I have a cartoon all about this, one I made up long before Oumuamua appeared, about how to catch a comet that is on a hyperbolic trajectory out of the solar system.

Basically, you need a harpoon with a bungee cord attached. Technology to do this is very much on the extreme limits of what is possible with current materials. Have you ever tried to harpoon something going past you at tens of kilometres per second?

dv said:

Next time

This.

It’s too late for this one, no matter what you try.

mollwollfumble said:

dv said:

Next time

I have a cartoon all about this, one I made up long before Oumuamua appeared, about how to catch a comet that is on a hyperbolic trajectory out of the solar system.

Basically, you need a harpoon with a bungee cord attached. Technology to do this is very much on the extreme limits of what is possible with current materials. Have you ever tried to harpoon something going past you at tens of kilometres per second?

That is one way to approach this. It is about as likely to approach any other attempts as well.

Michael V said:

dv said:

Next time

This.

It’s too late for this one, no matter what you try.

yeah, well.

Doesn’t matter. When the alien probe reports to its masters that life exists around Sol, there will be more ships arriving in future.

Bubblecar said:

roughbarked said:

Bubblecar said:

Why bother?

it is science. Why ask?

It may be science but it would require a fairly extreme effort that doesn’t seem to be justified given that it’s just going to be another funny-shaped asteroidy thing.

fantasizing about the fantastic, in detail, the intellectual test of imagining the challenge, to not do it practice, to explore why not to do it, or why it wouldn’t be done, people do that all the time.

dv said:

Here’s the path of ʻOumuamua as it passed through the solar system about a year ago. At its fastest it was travelling around 320000 km/h. 15 months after perihelion, it is already further from the Sun than Saturn is.

I wondered what the fastest celestial object ever observed in the solar system was (heliocentric speed): it’s probably Comet Lovejoy, which was moving at over 2 million km/h at perihelion, or Great Comet of 1843 which was going a similar speed.

The two unusual things about ʻOumuamua were:
1/ It’s strongly hyperbolic orbit, indicating an origin outside the solar system. The maths indicate that this can’t be something that was in the Oort cloud that was perturbed or anything like that. It came from somewhere else (maybe the dwarf star HIP 3757), and it came in fast: it was pegging at about 95000 km/h before it even reached the solar system and it will leave at the same speed.

2/ Based on its light curve, it is either elongated like a pen (about a 10:1 length:width ratio), or it is extremely flat and thin like a pancake.

It is a bit reddish but that’s not uncommon. Probably tholins. Or racing stripes.

So one other thing I was wondering was: could NASA build something to run a flyby of it?

It would be a big ask for a couple of reasons. 1/ It is moving ridiculously fast. It will be past the orbit of Pluto by 2023. And to catch it, the spacecraft has to be going faster than that. 2/ Because of its location, a Jupiter gravity assist is not an option. So all of the speed is going to have to come from rocketry.
So, working backwards from the objective, how much rocketry is that? Does NASA have that much rocketry? Is it all the rocketry?

Suppose the craft had the specs of the New Horizons craft. Because of signal strength issues we would want the encounter to be within 60 AU of the sun. That means the encounter has to happen by 2027. NASA already has some spare parts for the NH, and they have the design obviously: let’s say they got it manufactured, assembled and tested within a year from now so that it had 7 years to get to specific location 60 AU away.

Timing it to take maximum advantage of the Earth’s orbital speed, you’re still going to need, best case scenario, 21 km/s of delta-V from LEO.

None of the off-the-shelf hardware is well tuned to this task, but you could actually do it using SpaceX’s Falcon Heavy. It would have to launch straight to interplanetary trajectory, no messing about with an intermediate LEO phase, so yeah you’d want to be pretty sure of your guidance. Also it would mean using the non-environmentally friendly “zero reused” configuration and also it would make Elon Musk richer.

Don’t try to match velocities, that’s a useless waste of a comet. Try this.

dv said:

Or racing stripes.

Ok i laughed

Could an interstellar object impact a planet or is it moving to fast to be captured by a planets gravity

Cymek said:

Could an interstellar object impact a planet or is it moving to fast to be captured by a planets gravity

Its path will be deviated by the planet’s gravity.

Tamb said:

Cymek said:

Could an interstellar object impact a planet or is it moving to fast to be captured by a planets gravity

Its path will be deviated by the planet’s gravity.

Was thinking compared to anything else its moving extremely fast and if it’s an interstellar asteroid is likely to be quite dense as well so it would have a significant amount of kinetic energy.

It would be an interesting project to land on one and set up an automated factory to harvest useful resources and build a transmitter than can last for many decades.

Cymek said:

Could an interstellar object impact a planet or is it moving to fast to be captured by a planets gravity

Yes

They scanned it for signs of artificial signals and nothing, could they have sent it a transmission in case it was a dormant probe waiting for a signal to wake up

Dropbear said:

Cymek said:

Could an interstellar object impact a planet or is it moving to fast to be captured by a planets gravity

Yes

Yes. And that’s the start of the plot for the book “moonfall” by Jack McSomethingorother.

“The discovery of an interstellar comet on a collision course with the moon spells catastrophic destruction not only for Moonbase — Earth’s first lunar colony — but for the planet itself …”

Cymek said:

Could an interstellar object impact a planet or is it moving to fast to be captured by a planets gravity

The former

Cymek said:

They scanned it for signs of artificial signals and nothing, could they have sent it a transmission in case it was a dormant probe waiting for a signal to wake up

sure

dv said:

Here’s the path of ʻOumuamua as it passed through the solar system about a year ago.

…

So one other thing I was wondering was: could NASA build something to run a flyby of it?

It would be a big ask for a couple of reasons. 1/ It is moving ridiculously fast. It will be past the orbit of Pluto by 2023. And to catch it, the spacecraft has to be going faster than that. 2/ Because of its location, a Jupiter gravity assist is not an option. So all of the speed is going to have to come from rocketry.
So, working backwards from the objective, how much rocketry is that? Does NASA have that much rocketry? Is it all the rocketry?

Suppose the craft had the specs of the New Horizons craft. Because of signal strength issues we would want the encounter to be within 60 AU of the sun. That means the encounter has to happen by 2027. NASA already has some spare parts for the NH, and they have the design obviously: let’s say they got it manufactured, assembled and tested within a year from now so that it had 7 years to get to specific location 60 AU away.

Timing it to take maximum advantage of the Earth’s orbital speed, you’re still going to need, best case scenario, 21 km/s of delta-V from LEO.

None of the off-the-shelf hardware is well tuned to this task, but you could actually do it using SpaceX’s Falcon Heavy. It would have to launch straight to interplanetary trajectory, no messing about with an intermediate LEO phase, so yeah you’d want to be pretty sure of your guidance. Also it would mean using the non-environmentally friendly “zero reused” configuration and also it would make Elon Musk richer.

Going back to dv’s original question, but reframing it as follows:

Assuming that there was an impactor spacecraft on the launch pad ready to launch at the precise moment that the orbit of ʻOumuamua was first deduced to be hyperbolic, could we have got the impactor spacecraft to any point on the comet’s path (no attempt to match velocities) before the comet got there?

Rule out any idea of a gravitational slingshot off Venus, Mars or Jupiter, that would be way too slow.

Because the comet’s orbit is way out of the plane of the planets, we can’t rely on much speed from Earth’s own orbit.

“it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakala Observatory, Hawaii, on 19 October 2017, 40 days after it passed its closest point to the Sun. When first seen, it was about 33,000,000 km (0.22 AU) from Earth (about 85 times as far away as the Moon), and already heading away from the Sun.”

Now, 0.22 AU from Earth would take about … let’s be really optimistic and say 40 km/s, 9.5 days to traverse. The speed of ʻOumuamua at the same time would have been about 106 km/s in a direction away from us.

No chance of catching it, even at the time of first discovery.

To have a chance of catching an interstellar comet, even with the assumption of having an impactor spacecraft already on the launchpad ready the launch, it would have to be spotted at least 10 days before closest approach to Earth. That would be at a distance of about 0.6 AU away, where it would be only as bright as 0.14 times as bright as ʻOumuamua at discovery. That’s an extra 2 in magnitude above what is possible with current astaroid-finding telescopes.

A big ask all around. But not totally impossible.

mollwollfumble said:

dv said:

Here’s the path of ʻOumuamua as it passed through the solar system about a year ago.

…

So one other thing I was wondering was: could NASA build something to run a flyby of it?

It would be a big ask for a couple of reasons. 1/ It is moving ridiculously fast. It will be past the orbit of Pluto by 2023. And to catch it, the spacecraft has to be going faster than that. 2/ Because of its location, a Jupiter gravity assist is not an option. So all of the speed is going to have to come from rocketry.
So, working backwards from the objective, how much rocketry is that? Does NASA have that much rocketry? Is it all the rocketry?

Suppose the craft had the specs of the New Horizons craft. Because of signal strength issues we would want the encounter to be within 60 AU of the sun. That means the encounter has to happen by 2027. NASA already has some spare parts for the NH, and they have the design obviously: let’s say they got it manufactured, assembled and tested within a year from now so that it had 7 years to get to specific location 60 AU away.

Timing it to take maximum advantage of the Earth’s orbital speed, you’re still going to need, best case scenario, 21 km/s of delta-V from LEO.

None of the off-the-shelf hardware is well tuned to this task, but you could actually do it using SpaceX’s Falcon Heavy. It would have to launch straight to interplanetary trajectory, no messing about with an intermediate LEO phase, so yeah you’d want to be pretty sure of your guidance. Also it would mean using the non-environmentally friendly “zero reused” configuration and also it would make Elon Musk richer.

Going back to dv’s original question, but reframing it as follows:

Assuming that there was an impactor spacecraft on the launch pad ready to launch at the precise moment that the orbit of ʻOumuamua was first deduced to be hyperbolic, could we have got the impactor spacecraft to any point on the comet’s path (no attempt to match velocities) before the comet got there?

Rule out any idea of a gravitational slingshot off Venus, Mars or Jupiter, that would be way too slow.

Because the comet’s orbit is way out of the plane of the planets, we can’t rely on much speed from Earth’s own orbit.

“it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakala Observatory, Hawaii, on 19 October 2017, 40 days after it passed its closest point to the Sun. When first seen, it was about 33,000,000 km (0.22 AU) from Earth (about 85 times as far away as the Moon), and already heading away from the Sun.”

Now, 0.22 AU from Earth would take about … let’s be really optimistic and say 40 km/s, 9.5 days to traverse. The speed of ʻOumuamua at the same time would have been about 106 km/s in a direction away from us.

No chance of catching it, even at the time of first discovery.

To have a chance of catching an interstellar comet, even with the assumption of having an impactor spacecraft already on the launchpad ready the launch, it would have to be spotted at least 10 days before closest approach to Earth. That would be at a distance of about 0.6 AU away, where it would be only as bright as 0.14 times as bright as ʻOumuamua at discovery. That’s an extra 2 in magnitude above what is possible with current astaroid-finding telescopes.

A big ask all around. But not totally impossible.

Really need a nuclear powered rocket

Cymek said:

mollwollfumble said:

dv said:

Here’s the path of ʻOumuamua as it passed through the solar system about a year ago.

…

So one other thing I was wondering was: could NASA build something to run a flyby of it?

It would be a big ask for a couple of reasons. 1/ It is moving ridiculously fast. It will be past the orbit of Pluto by 2023. And to catch it, the spacecraft has to be going faster than that. 2/ Because of its location, a Jupiter gravity assist is not an option. So all of the speed is going to have to come from rocketry.
So, working backwards from the objective, how much rocketry is that? Does NASA have that much rocketry? Is it all the rocketry?

Suppose the craft had the specs of the New Horizons craft. Because of signal strength issues we would want the encounter to be within 60 AU of the sun. That means the encounter has to happen by 2027. NASA already has some spare parts for the NH, and they have the design obviously: let’s say they got it manufactured, assembled and tested within a year from now so that it had 7 years to get to specific location 60 AU away.

Timing it to take maximum advantage of the Earth’s orbital speed, you’re still going to need, best case scenario, 21 km/s of delta-V from LEO.

None of the off-the-shelf hardware is well tuned to this task, but you could actually do it using SpaceX’s Falcon Heavy. It would have to launch straight to interplanetary trajectory, no messing about with an intermediate LEO phase, so yeah you’d want to be pretty sure of your guidance. Also it would mean using the non-environmentally friendly “zero reused” configuration and also it would make Elon Musk richer.

Going back to dv’s original question, but reframing it as follows:

Assuming that there was an impactor spacecraft on the launch pad ready to launch at the precise moment that the orbit of ʻOumuamua was first deduced to be hyperbolic, could we have got the impactor spacecraft to any point on the comet’s path (no attempt to match velocities) before the comet got there?

Rule out any idea of a gravitational slingshot off Venus, Mars or Jupiter, that would be way too slow.

Because the comet’s orbit is way out of the plane of the planets, we can’t rely on much speed from Earth’s own orbit.

“it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakala Observatory, Hawaii, on 19 October 2017, 40 days after it passed its closest point to the Sun. When first seen, it was about 33,000,000 km (0.22 AU) from Earth (about 85 times as far away as the Moon), and already heading away from the Sun.”

Now, 0.22 AU from Earth would take about … let’s be really optimistic and say 40 km/s, 9.5 days to traverse. The speed of ʻOumuamua at the same time would have been about 106 km/s in a direction away from us.

No chance of catching it, even at the time of first discovery.

To have a chance of catching an interstellar comet, even with the assumption of having an impactor spacecraft already on the launchpad ready the launch, it would have to be spotted at least 10 days before closest approach to Earth. That would be at a distance of about 0.6 AU away, where it would be only as bright as 0.14 times as bright as ʻOumuamua at discovery. That’s an extra 2 in magnitude above what is possible with current astaroid-finding telescopes.

A big ask all around. But not totally impossible.

Really need a nuclear powered rocket

Wouldn’t hurt.

Much.