If the public seems more interested in spaceflight as a vehicle for streaming TV dramas, the reality of both the Europa Clipper liftoff and the astounding ‘catch’ of SpaceX’s Starship booster may kindle a bit more interest in exploring nearby space. When I say ‘nearby,’ bear in mind that on this site the term refers to the entire Solar System, as we routinely discuss technologies that may one day make travel to far more distant targets possible. But to get there, we need public engagement, and who could fail to be thrilled by a returning space booster landing as if in a 1950’s SF movie?
Europa may itself offer another boost if Europa Clipper’s science return is anything like what it promises to be. Closing to 15 kilometers from the surface and making 49 passes over the icy ocean world, the spacecraft may give us further evidence that outer system moons can be venues for life. We also have the European Space Agency’s Jupiter Icy Moons Explorer (JUICE), which will study Europa, Callisto and, in a spectacular move, end up orbiting Ganymede for extended close-up observations.
Image: Europa Clipper begins its journey. Credit: SpaceX.
JUICE gets to Jupiter in July of 2031, while Europa Clipper starts its flybys in the same year, though arriving in 2030. As a measure of how tricky it can be to get to these destinations, both craft make flybys of other worlds, returning in fact to the Earth for some of these. Europa Clipper’s journey will be marked by gravity assists from Mars in February of 2025 and Earth in December 2026. JUICE has already performed one Earth/Moon flyby and will make a flyby of Venus (August, 2025) followed by two Earth flybys (September 2026 and January 2029). A long and winding road indeed!
Speaking of flybys, it’s interesting to note that we have two cometary appearances this month. Comet C/2023 A3 (Tsuchinshan-ATLAS) and C/2024 S1 (ATLAS) are both likely to be visible in October, with the latter closest to Earth on October 24 as it swings toward Sol where it will likely disintegrate. The former should make an appearance in the western sky just after sunset before growing fainter in the latter part of the month. C/2023 A3 appears to be an Oort Cloud object, or long period comet, with an orbital period of some 80,000 years. Short-period comets (Halley’s Comet is one of these) have much shorter orbits, with Halley’s showing up every 76 years.
I find the Oort Cloud a fascinating subject, for it’s based on deduction and not observation. Astronomer James Wray (Georgia Tech), writing in The Conversation, makes the point that while we can’t directly image this vast collection of comets, likely numbering in the hundreds of billions, we can estimate that it extends possibly as far as halfway to the Alpha Centauri system. That’s an intriguing thought, for it means our cometary cloud may intermingle with an equivalent cloud (if one exists) from the Centauri stars. The space covered by our first interstellar probes is not vacant, though the distances between individual objects would still be vast. On the other hand, if the theory that the Oort Cloud formed because of interactions with the giant planets, it’s possible that in the absence of such planets (still not demonstrated), Centauri A and B may not have formed such a cloud.
Wray makes the case that long-period comets are conceivably our greatest planetary threat, outranking near Earth asteroids in degree of danger since an incoming Oort object would likely not be spotted until well inside the planetary system, giving us little time to react. ‘Oumuamua, after all (not an Oort object) was discovered after its closest approach to Earth.
Cometary flybys of our Sun will always be cherished for their visual appeal as ices evaporate and a tail forms, and a collision course with Earth is a highly unlikely scenario, but it’s always best to consider the prospects. Wray puts it this way:
One way to prepare for these objects is to better understand their basic properties, including their size and composition. Toward this end, my colleagues and I work to characterize new long-period comets. The largest known one, Bernardinelli–Bernstein, discovered just three years ago, is roughly 75 miles (120 kilometers) across. Most known comets are much smaller, from one to a few miles, and some smaller ones are too faint for us to see. But newer telescopes are helping. In particular, the Rubin Observatory’s decade-long Legacy Survey of Space and Time, starting up in 2025, may double the list of known Oort Cloud comets, which now stands at about 4,500.
The European Space Agency’s Comet Interceptor mission, scheduled for launch later in this decade, should offer an option for intercepting an Oort Cloud comet when one appears, making it possible to learn more about these objects in terms of their composition and possible role in the delivery of volatiles to the inner system. Oort comets are tricky because their wide orbits mean gravitational influences from other stars can nudge one into a solar close pass without any prior warning. An incoming long-period comet, writes Wray, might offer mere weeks or days to prepare any defense measures we have in place. Even so, the odds of an impact are extremely low.
Image: A stunning return. The Starship booster comes home. Credit: SpaceX.
All this is by way of hoping public interest in space will be quickened both by recent mission successes, ongoing exploration of possible sources of life, and the appearance of the occasional comet. The startling SpaceX success with Starship’s ‘catch’ underlines that technological advances, like comets, can seem to come out of nowhere when we’re not paying attention. I’m thinking back to the science fiction I read as a kid and realizing that watching Starship’s booster descend was right out of Astounding Stories. Heinlein would have loved it, and indeed foreshadowed what unfolded on Sunday.
As SpaceX communications manager Dan Huot put it: “What we just saw, that looked like magic.”
If Oort cloud objects extend for lightyears, is it possible that nomadic/rogue planets rather than approaching stellar systems are the cause of the orbital perturbations resulting in comets? I ask because wasn’t there a calculation that suggested the presence of such planets was likely well within the volume defined by a 4.3 ly radius? This would allow more perturbations over time than stars closely approaching our sun, and the extent of the Oort cloud would ensure more opportunities for perturbations from these planets. While the new Vera Rubin observatory should detect more Oort cloud objects, might it not also be able detect these planets too?
Good point. And I think the calculations re rogue planets within the 4.3 light year radius are pretty well accepted. Without knowledge of the numbers it’s hard to go much further, but they would certainly produce gravitational effects and disruptions in the Oort.
@Alex
I have seen , at least a few, paper about stellar passage and the stability of the solar system, more papers on stellar passage perturbations on the Oort cloud.
No paper about rogue planet perturbation of the Oort Cloud comes to mind.
It is interesting that there has been modeling of solar system formation that suggest that the solar system has ‘companion’ planets ‘near’ the solar system. These planets could be there because they would have orbits about the center of the galaxy similar to the sun. (In some of these models these are planets ‘ejected’ during the formation of the solar system. Solar Rogues.)
Check here: https://www.popularmechanics.com/space/solar-system/a19574767/passing-star-nudged-solar-system-70000-years-ago-may-have-sent-comets-flying-in/
Ah Margarita … interesting to know you are a ‘viewer’ here.
(A researcher in the area of Exoplanets.)
Another paper of interest is downloadable
https://academic.oup.com/mnras/article/527/3/6126/7452883
There is expected to many thousand to tens of thousands of smaller objects between the stars but only a few say jupiter mass ones. So we could have a few exoJupiters closer than the stars but they only a have small mass so would IMO have no real influence on the orbits of our solar system.
Using your example of Jupiter, it is 1/1000th the mass of our sun. Therefore its gravitational attraction is 0.001 implying that for any unit of gravitation our sun provides, Jupiter will have the same attraction at 1000th the distance.
The nearest star is Proxima, 4.3 ly away, = 272,000 AU. Therefore a Jupiter mass planet will have the same effect at 272 AU as Proxima.
If any rogue planet is currently traveling within the Oort cloud, it would have the same effect as Proxima for any body if it was just 272 AU away from it. But given that we know that a few stars will get closer to our sun over many millions of years, isn’t it just as likely that a Jupiter mass planet will perturb an Oort object within that time frame, especially if there are several such planets moving through the Oort cloud?
Now maybe space is so big that it could pass through the Oort without perturbing an Oort object, perhaps needing to be within 5-10 AU to have any perturbing effect. However, if there are a number of such planets constantly traveling through the Oort, what is the likelihood that they have a significant perturbing effect compared to a star that is less frequently coming much closer.
It seems to me that this is a case for modeling to determine the relative effects and patterns of perturbations of stars vs. rogue planets. Maybe the answer is that they have very little effect, although this may depend on their relative motion and their number. Can we do a BoE calculation as an estimate?
This is an old study, I think the Roman Nancy spacecraft is designed to look for these rogue planets specifically.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwj2z6qg3pOJAxXDUkEAHQt4NRI4FBAWegQIKhAB&url=https%3A%2F%2Flegacy.ciera.northwestern.edu%2FJackson2011%2Ftalks%2Fsumi_takahiro.pdf&usg=AOvVaw3vGTCmmDTz1GB-smy_X8Gi&opi=89978449
Alex, Proxima is actually only less than 130 times the mass of Jupiter, meaning a hypothetical Jupiter-mass planet will have the same effect as Proxima at 1/130 the distance, i.e. roughly 2100 AU, meaning it would be able to do even more damage.
A Jupiter-mass planet orbiting or flying alongside the Sun as Proxima does with the AC pair, will also have a lot more time to perturb comets than a Proxima-mass star which just flies past and goes its merry way.
It is also possible that the non-hypothetical Proxima which actually exists well within any Oort cloud which the AC pair may have, is flinging comets in any direction including towards our Solar system. Some may start arriving several millenia after AC’s closest approach 28000 years from now.
Here is a very good chart that shows stars that have made close passes to the solar system. HD 7977 a G3 type star with a mass higher then the sun passed at below a half of light year of the solar system 2.79 million years ago. Well into the Oort cloud, we should still be seeing many comets orbits gravitational perturbations by such a large star for millions of years after it passed…
https://en.wikipedia.org/wiki/HD_7977#/media/File:Objects_between_sun_and_alpha_centauri.jpg
Both stars oort clouds should have passed through each other, we should have had a direct shower from these passing stars.
Very good point and in fact there was a large impact 280,000 years after its passing. This may be the first known impactor that may be from another solar system.
The Eltanin impact is thought to be an asteroid impact in the eastern part of the South Pacific Ocean that occurred around the Pliocene-Pleistocene boundary approximately 2.51 ± 0.07 million years ago.
https://en.wikipedia.org/wiki/Eltanin_impact#
And let us not forget rogue black holes:
https://en.wikipedia.org/wiki/Rogue_black_hole
The above piece says they are on the edge of the Milky Way galaxy due to mergers, but I am more than certain there are plenty of others roaming throughout our galaxy.
The current estimate, in fact, is 100 million. See here:
https://www.astronomy.com/science/hunting-rogue-black-holes-in-the-milky-way/
I am sure their numbers are much larger than that. And who knows what else is out there that astronomers do not have a clue about yet?
Although there are over a hundred million BH’s estimated the nature of their birth gives them a kick and quite a high one at that,it has the effect of pushing them into halo orbits around the milky way diluting them.
Yes, but those black holes have to travel there through interstellar space, so one hundred million BHs roaming the galaxy need to be taken into consideration.
And how many brown dwarfs are out there that we have trouble detecting…
https://phys.org/news/2024-10-twins-mystery-famed-brown-dwarf.html
https://www.nasa.gov/missions/webb/nasas-webb-identifies-tiniest-free-floating-brown-dwarf/
As for starship I see them building loads of these towers around the earth with the booster just landing at another one down range to refuel. I believe this system of reusablilty will allow cheap and easy access to space to build the infrastructure we badly need.
Speaking of the Clipper and the Comet…
The Clipper and the Comet (APOD: 2024 Oct 17)
Image Credit & Copyright: Ben Cooper (Launch Photography)
https://apod.nasa.gov/apod/ap241017.html
Explanation: NASA’s Europa Clipper is now headed toward an ocean world beyond Earth. The large spacecraft is tucked into the payload fairing atop the Falcon Heavy rocket in this photo, taken at Kennedy Space Center the day before the mission’s successful October 14 launch.
Europa Clipper’s interplanetary voyage will first take it to Mars, then back to Earth, and then on to Jupiter on gravity assist trajectories that will allow it to enter orbit around Jupiter in April 2030.
Once orbiting Jupiter, the spacecraft will fly past Europa 49 times, exploring a Jovian moon with a global subsurface ocean that may have conditions to support life.
Posing in the background next to the flood-lit rocket is Comet Tsuchinsan-ATLAS, about a day after the comet’s closest approach to Earth. A current darling of evening skies, the naked-eye comet is a visitor from the distant Oort cloud.
http://www.launchphotography.com/Photographer.html
http://www.launchphotography.com/
Starship Asterisk* • APOD Discussion Page
https://asterisk.apod.com/discuss_apod.php?date=241017
#APOD
No feeding troughs were any part of the culture or budget for SpaceX, unlike government agencies where bureaucratic bloat is de rigueur down to the smallest branch office. Any sufficiently honest social system will seem to the rest like magic.
This was and is true even in the former Soviet Union and today’s Russia, because of the perks associated with bureaucratic rank, but siphoning off taxpayer funds was not a part of their world.