One hull crack located in ISS, another one suspected:
The specialists have discovered one more crack at the International Space Station and suspect that yet another one exists, ISS Russian Segment head Vladimir Solovyov told [news channel] Rossiya-24.
"So far, we have found one place and suspect another, where as some kind of leak exists. We must bring a powerful microscope on a cargo spacecraft and use to examine this place. We are not totally certain so far," Solovyov said.
[...] "We are working on it, of course. We understand clearly that these places are at issue. The[sic] are indeed not airtight, we understand that there could be some other places, but there is no horror in that, I can say it responsible[sic] as the mission head," he assured.
Also At: BoingBoing
Previously:
(2018) NASA and Roscosmos Release Joint Statement on ISS Leak Amid Rumors
(2018) Controversy Over ISS Leak Continues, Spacewalk Planned for November
Related Stories
Russian theory that NASA sabotaged the space station spreading like wildfire
As you may recall, a low-pressure leak occurred aboard the International Space Station in late August. Eventually the crews traced the leak to the orbital module of a Russian Soyuz spacecraft that had arrived at the station in June. After the problem was traced to what appears to be a manufacturing defect, the head of Russia's space program essentially called for the head of whoever made the error. Now, however, something entirely new is afoot in Russia. A growing number of Russian publications have been putting forth an absurd new theory—that a NASA astronaut deliberately caused the leak on board the station in order to force the evacuation of a sick crew member. The story has spread like wildfire during the last 24 hours, according to Robinson Mitchell, who translates Russian space stories for Ars.
One of the most prominent articles was published Wednesday in Kommersant, which says Russian investigators are vigorously pursuing the claim that Americans may have damaged the Soyuz deliberately. Publicly, Roscosmos leader Dmitry Rogozin was quoted as saying about Russia's investigation into the leak, "Results we have received do not give us an objective picture. The situation is much more complex than we earlier thought." Privately, however, several sources from the space agency are leaking much juicier comments to the Russian media. "Our Soyuz is next to the Rassvet (Dawn) module, right next to the hatch into the American segment of the station," one source told Kommersant. "Access to our ship is possible only with the permission of our commander, but we cannot exclude an unsanctioned access by the Americans."
After more speculation about cause of ISS leak, NASA issues another statement
A thorough Russian investigation of a leak that occurred in August in the orbital module of a Russian Soyuz spacecraft, which is attached to the International Space Station, will not be completed until November. But this week, the head of the Russian space agency Roscosmos reignited controversy about the leak with some comments during a television appearance.
A preliminary investigation, according to Russia's chief spaceflight official, Deputy Prime Minister Dmitry Rogozin, "concluded that a manufacturing defect had been ruled out which is important to establish the truth." So if it wasn't a manufacturing defect, then what was it? As Rogozin did not say, this re-fueled speculation in some media reports that the hole was intentionally drilled by NASA astronauts in space. This theory is nonsensical, but it appears to play well to Russian audiences.
After these latest comments and with an imminent Soyuz spacecraft launch on October 11 that will carry NASA astronaut Nick Hague to the International Space Station, the US space agency felt the need to put out a new statement on Wednesday. It reads:
On Aug. 29, 2018 a small hole was discovered on the International Space Station. This resulted in a pressure leak. The hole has been identified and fixed by space station crew.
Russian media recently reported that General Director Rogozin said the hole was not a manufacturing defect. Ruling out a manufacturing defect indicates that this is an isolated issue which does not categorically affect future production.
This conclusion does not necessarily mean the hole was created intentionally or with mal-intent. NASA and Roscosmos are both investigating the incident to determine the cause. The International Space Station Program is tentatively planning a spacewalk in November to gather more information.
On October 11, American Astronaut Nick Hague and Russian Cosmonaut Alexey Ovchinin will launch to the International Space Station on a Russian Soyuz MS-10 spacecraft from the Baikonur Cosmodrome in Kazakhstan. Administrator Bridenstine is scheduled to attend the launch and plans to meet with Mr. Rogozin. This will be their first in-person meeting. They had a telephone call on September 12 during which they discussed the International Space Station leak.
Previously: Russian Space Chief Vows to Find "Full Name" of Technician Who Caused ISS Leak
NASA and Roscosmos Release Joint Statement on ISS Leak Amid Rumors
(Score: 0) by Anonymous Coward on Monday January 25 2021, @02:27AM (16 children)
Let ISS sink.
We need to put up another "ISS" on a higher orbit, the real "space."
(Score: 0) by Anonymous Coward on Monday January 25 2021, @02:39AM (5 children)
Waste of money and resources.
Leave module and get one of these systems. https://www.greenbuildingadvisor.com/article/aeroseal-rolls-out-air-sealing-technology-for-houses [greenbuildingadvisor.com] Designed to fill cracks and air leaks.in new homes. Also use similar for sealing air ducts.
Give it lift to hieghter orbit or to the moon or mars. Large space warehouse if nothing else.
(Score: 5, Insightful) by tangomargarine on Monday January 25 2021, @03:47AM (3 children)
If you're talking about the ISS here, I don't think that would work for several different reasons.
1) The ISS is already past its design life,
2) it's full of mold and stuff that can't be cleaned out properly, and
3) being in Low Earth Orbit means that the astronauts are relatively protected from radiation by the atmosphere or something? Boosting the ISS out of that orbit exposes the inhabitants to all that. Because the walls of the thing aren't actually that thick. IIRC the Apollo missions that went around the moon were only out there for a couple days, so the astronauts didn't get enough exposure to harm them much. People live on the ISS for over a year at a time. Even if you were just using it as a warehouse or something, you'd want people regularly checking in on it in case something breaks.
Yes all this stuff is rather expensive (if the numbers I'm finding are accurate, the ISS in total cost only 22% of the U.S.'s annual "defense" budget), but you can't just leave something designed to last 15 years out in orbit indefinitely (current projection is 26 years) and expect it to stay useful.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 3, Informative) by takyon on Monday January 25 2021, @06:20AM (2 children)
With Starship, a station much larger than the ISS could be built for relatively nothing. Maybe 1-10% of the total cost of ISS. Maybe the next version will not have a persistent mold problem or will be even more modular making it easy to swap out every piece of the station over a few decades.
There are plenty of radiation concerns almost everywhere beyond Earth, to the point where IIRC astronauts will only be staying one month at a time at the Lunar Gateway. But maybe there is a compromise.
https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Implications_for_space_travel [wikipedia.org]
2 to 4 Earth radii is 12,756 to 25,513 kilometers. Geosynchronous orbit is 35,786 kilometers, and the Moon is roughly 384,400 km away. The ISS orbits between around 330 to 410 km, with an orbital decay of around 2 kilometers per month.
It would take more energy to reach that higher orbit, but maybe it would be worthwhile to change it up, and eliminate the need for periodic re-boosting.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: -1, Troll) by Anonymous Coward on Monday January 25 2021, @07:18AM (1 child)
Like, only a 1.6 Trillion space bucks? Whatever are you talking about, takyon! Unlimited taxpayers dollars for, what?
(Score: 2) by MIRV888 on Monday January 25 2021, @07:42AM
Your are thinking of that last aircraft carrier. This is about space travel.
(Score: 2) by Grishnakh on Monday January 25 2021, @06:03PM
I've heard of this stuff before, and I don't see the benefit to duct-sealing: if your ducts leak, where does that air go? Usually, into the interior of the house. What space are you trying to heat or cool? The interior of the house. So how is sealing leaky ductwork improving efficiency? The only thing it does is improve the delivery of heated/cooled air to the rooms you want it to go to, but we don't do any serious vent balancing in US homes, so what's the point?
As for sealing the building envelope itself, obviously that improves efficiency, but at a cost: the tighter your house is sealed, the worse the indoor air quality is. So your HVAC efficiency is great, but now you're breathing stale, O2-depleted, and polluted air. Why don't HVAC systems have any kind of air-exchange systems to replace old indoor air with fresh outdoor air? Or how about a system to stop heating or cooling altogether when the air outside is closer to the temperature you want than the air inside? Our HVAC systems are stupidly designed.
(Score: 2) by takyon on Monday January 25 2021, @06:02AM
The ISS will continue to operate through at least 2030. After that, it would be nice if they could capture modules with Starship and bring them to the Smithsonian, instead of burning them. Russia was planning to reuse some of its modules to make a new station but who knows if they will follow through.
The Lunar Gateway is still on the agenda [nasa.gov]. That would be smaller than ISS and substantially cheaper, and fulfill your requirement of "higher orbit", although there's no "real" reason to put a space station there.
The next big station should use inflatable modules or otherwise offer a lot of volume. Maybe they can put it between the inner and outer Van Allen belts to eliminate the need for the periodic re-boosting.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by Runaway1956 on Monday January 25 2021, @01:18PM (8 children)
No, don't allow the ISS to sink into the atmosphere. Better to move it up into a higher orbit. If you choose to abandon the ISS, park it in a nice safe "junk orbit" and start salvaging useful items from it. There is a helluva lot of money invested in what is there already, why burn it up?
(Score: 2) by Socrastotle on Monday January 25 2021, @02:44PM (3 children)
The reason the ISS was so expensive is the same reason (with current gen technology) that this idea is not so feasible. How much do you think a 16oz bottle of water on the space station would be worth? During the Space Shuttle era, the answer was about $25,000 since that's what it cost to send a pound to space. SpaceX has gotten this figure dramatically down and you can now send a pound to space for around $1200, but launch costs are still generally going to be vastly larger for nearly all payloads.
This is why people are talking about Star Ship as such a huge deal. If we can get the price of sending stuff into orbit down to reasonable levels, then suddenly you can start thinking of all sorts of really interesting ideas. Because right now any idea you have has a barrier to entry of $1000+ per pound, and that restricts just about everything. This is also one of the reasons I've gradually grown more fond of the idea of a moon development. The notion of it as a 'stepping stone' to Mars is nonsensical for reasons outside the scope of this post, but as its own independent entity to be used for manufacturing and development - it seems like it could make a lot of sense. The initial development there could also lead to more recreational development spurring on commercial lunar tourism to a region that will likely end up as all early colonies do. In other words: moon poon. Who wouldn't wanna give that a go?
(Score: 2) by Grishnakh on Monday January 25 2021, @06:19PM (2 children)
The "stepping stone" idea for Luna is indeed nonsense, at least as far as a singular mission. But the whole idea of bypassing the Moon and sending missions straight to Mars is stupid. We need to develop mining and manufacturing ability off-world before we start trying to establish colonies on other bodies. Luna is literally 3 days away with 1960s technology (and probably today's too), whereas Mars is 6-18 months away depending on relative orbital positions. Humans probably will not even survive the trip to Mars because of the radiation, so why are we even talking about such trips? There's radiation going to Luna too, but 3 days of it isn't significant compared to 100x that much from a trip that much longer.
The Moon is close, it has raw materials, it probably even has lava tubes that can be used as habitats to avoid radiation exposure. It's the perfect place to start experimenting with offworld refining and manufacturing, using material mined on Luna, or brought there from nearby asteroids. And it's a good place to build much, much larger ships (with good radiation shielding) for colonization trips to Mars.
(Score: 2) by Socrastotle on Tuesday January 26 2021, @06:55AM (1 child)
Mars is ~9 months away using current (and older) tech. SpaceX is aiming to get it down to about 6 months. And humans will easily survive the radiation. Not only are there countless viable ways to help with shielding (probably most notably being water/waste/fuel), the problem is not that it just suddenly fries you, but rather that you will have a significantly increased chance of things like cancer later in life. But all things considered, it's a near irrelevant issue. Once we start move to other planets there will be much more imminent concerns than the shaving a few years off the average lifespan.
Mars will be much easier to develop than the moon for countless reasons:
- near identitical day/night cycle to Earth instead of 2 week long nights.
- comparable temperatures ranges to some places on Earth. the moon, by contrast, oscilates between above boiling and temperatures approaching absolute zero. redefining thermal expansion/contraction!
- 0.38g instead of near 0g gravity. better for both humans and industry.
- it has an atmosphere. the moon is pelted by a never-ending series of bullet (to rocket) like meteorites. most of those would burn up in Mars atmosphere similar to how they burn up in ours.
- the atmosphere also provides some degree of radiation protection meaning some time "outside" is perfectly safe.
- far greater mineral resources alongside area for development. Mars surface area is near identical to the Earth's land surface area. The moon's surface is smaller than Asia - huge of course, but colonization will likely drive exponential development/exploitation.
- a regolith on Mars somewhat comparable to Earth, contrasted to the wide widespread ultra-fine 'gunpowder smelling' regolith on Mars that's fine enough to get into just about everything.
Basically the Moon will be vastly more complex and difficult to develop than Mars. And what works on the Moon will likely have relatively little application to what works on Mars. It doesn't work as a stepping stone because it's simply going to be a lot harder. All you have going for you is less travel time. And that is indeed a big benefit, but one that should weighed against the complexities, and limited generalization, of its development.
SpaceX's goal is pretty straight forward. In 2022 they will be launching a number of Starships to Mars. These ships will be unmanned and contain the supplies and cargo the next crew will need. Assuming the launch and landing of these ships is successful, humans followin 2024. They will have ~6 months there, 9 months of time to work, and then 6 months back. So the basic question becomes simple. Can we create a biome humans could survive for in 2 years, in isolation - given let's say ~3000 cubic meters of space? And the answer there is obviously yes.
Had we not given up on space following our winning the race to the moon, we likely would have had a human settlement setup on Mars decades ago. Wernher von Braun (the brains behind our space program's success) even had laid out templates for Mars explanation that, had our space trajectory continued, would have seen us colonizing the planet around the 1980s. It's really not an especially huge challenge. The only issue is that there's no direct path to profit or influence, and so governments generally have relatively little interest in it. And it goes without saying that any significant colony on Mars will ultimately declare its own political independence so they're also being asked to fund something that they will not be able to control. This is why we had to wait until economic development reached the point such that even private corporations/individuals could fund large scale projects to other planets.
(Score: 1, Troll) by Grishnakh on Tuesday January 26 2021, @05:11PM
>Mars is ~9 months away using current (and older) tech. SpaceX is aiming to get it down to about 6 months.
No, it's not. It's 6-18 months, depending on where the planets are. SpaceX will never, ever have the technology to make their orbits synchronous, or in any other way make the transit time a single number (except maybe by intentionally going really slow when Earth and Mars are near each other).
> - near identitical day/night cycle to Earth instead of 2 week long nights.
Who cares? This is what artificial habitats are for. You can have day/night whenever you want.
> - comparable temperatures ranges to some places on Earth. the moon, by contrast, oscilates between above boiling and temperatures approaching absolute zero. redefining thermal expansion/contraction!
Who cares? This is what artificial habitats are for. Set the temperature to whatever you want. It's not like you're going to be living outside. Mars doesn't have a breathable atmosphere, and it has no magnetosphere, so radiation on the surface will kill you over time.
>- 0.38g instead of near 0g gravity. better for both humans and industry.
Wrong. Luna has 1/6g gravity, about half of Mars'. Better for industry is debatable: a lot of processes would benefit from lower gravity, not more.
>- it has an atmosphere. the moon is pelted by a never-ending series of bullet (to rocket) like meteorites. most of those would burn up in Mars atmosphere similar to how they burn up in ours.
Mars does not have an atmosphere; it has an "atmosphere". It's a puny 1/200 the pressure of Earth's. Maybe enough to deal with micro-meteorites, but again, who cares? You're not going to be living on the surface.
>- the atmosphere also provides some degree of radiation protection meaning some time "outside" is perfectly safe.
Very little.
> - far greater mineral resources alongside area for development. Mars surface area is near identical to the Earth's land surface area. The moon's surface is smaller than Asia - huge of course, but colonization will likely drive exponential development/exploitation.
Oh please; this won't be a concern for centuries. Besides, asteroids are more useful for minerals than the surface of Mars. The moon is just a better place for processing captured/mined asteroids.
> - a regolith on Mars somewhat comparable to Earth, contrasted to the wide widespread ultra-fine 'gunpowder smelling' regolith on Mars that's fine enough to get into just about everything.
Again, don't live on the surface, and I'm sure they can figure out protocols and technology to deal with the moon dust.
>Basically the Moon will be vastly more complex and difficult to develop than Mars.
Bullshit.
>All you have going for you is less travel time. And that is indeed a big benefit
It's such a big benefit that it outweighs everything else, by far.
>SpaceX's goal is pretty straight forward. In 2022 they will be launching a number of Starships to Mars. These ships will be unmanned and contain the supplies and cargo the next crew will need. Assuming the launch and landing of these ships is successful, humans followin 2024.
And what are these humans going to do there? Are they going to set up factories and mining operations in that time? I don't think so. If you can't do that, then all you have is an outpost dependent on constant resupply; what good is that exactly, other than scientific research? Basically this is just like the outposts on Antarctica--nice for learning about an extreme and remote environment and some penguins, but not useful at all as a permanent residence for humans in the future.
>The only issue is that there's no direct path to profit or influence, and so governments generally have relatively little interest in it.
Right, and that's why this is a waste of time and money. There's no profit potential because it's just too far away to really do anything highly useful for anyone back on Earth. Why should I spend a bunch of money so some wackos can go get themselves irradiated on another planet and do science experiments? For a few scientists, sure, that's fine; it's just like Antarctica. But you're trying to make it out like we have some kind of duty to send hordes of people and bootstrap civilization on Mars. For what? The Moon is much closer and has real industrial applications that are useful here on Earth: things can be manufactured on Luna in a low-g environment, using materials mined there or from asteroids, and sent here for consumption. Colonizing Mars does absolutely nothing for the people on Earth.
(Score: 2) by Grishnakh on Monday January 25 2021, @06:07PM (3 children)
The equipment itself is mostly worthless, except perhaps for a museum. The money "invested" was all spent in launching it; it's already burned up.
Remember Mir? It was worthless too at the end of its lifespan, which is why Russia simply de-orbited it and let it burn up in the atmosphere. A leaky, obsolete old space station just doesn't have much value left, and keeping it in orbit costs a lot of money (because you need to launch spacecraft to dock with it and then give it a boost burn). At best, the scrap metal might be worth something, but it'll cost far more to safely get the pieces back to earth where it can be melted down than it does to just get more metal somewhere else. (And we don't have the capability of refining or recycling metals in space yet.)
(Score: 2) by Runaway1956 on Monday January 25 2021, @06:15PM (2 children)
Somehow, I failed to make my point.
We're already giving the platform assistance to keep it in it's existing orbit. Just give it a longer, more sustained boost to put it into a much higher, more stable orbit. Park it in one of the lagrange points between the earth and the moon, and one day it can be a museum right there. IF it isn't cannibalized first for valuable materials.
(Score: 3, Informative) by Grishnakh on Monday January 25 2021, @06:30PM (1 child)
I'm not a rocket scientist (and I suspect you aren't either), but I'm pretty sure what you're proposing isn't technically feasible, or would be more difficult or expensive than simply building a whole new ISS at that Lagrange point. ISS is in a low orbit, and only avoids destruction because of its speed, and is deep in Earth's gravity well; the amount of energy needed to boost it completely out of that well into a Lagrange point would be enormous.
Some people have asked this same question on Quora:
https://www.quora.com/Could-the-ISS-be-nudged-out-of-Earths-orbit-and-into-the-Moons-orbit [quora.com]
https://www.quora.com/Could-the-International-Space-Station-be-navigated-to-a-Lagrange-point [quora.com]
Basically, the answers say it's theoretically possible, but it would take a whole bunch of Apollo-sized rockets, and it would end up destroying parts of the station anyway (esp. the solar panels) because they weren't designed for that much thrust. The amount of money (and fuel) needed to do what you're asking is astronomical, and that effort could be put towards much more useful things, such as building a colony on the Moon rather than preserving a museum piece.
(Score: 0) by Anonymous Coward on Monday January 25 2021, @11:04PM
No - just like a refrigerator magnet can move 6 ton pendulum (see Explorium). A little boost at the right time will elongate the the orbit little at time until it is in the right orbit. They do this satellites with getting to geosync orbits, uses a lot less fuel.
(Score: 2, Insightful) by Anonymous Coward on Monday January 25 2021, @02:40AM (9 children)
$10 in Flex Tape could knock that out right quick.
(Score: 0) by Anonymous Coward on Monday January 25 2021, @03:20AM
Just use the spray or the putty, the tape sticks to everything it touches and is hard to apply cleanly.
(Score: 1, Funny) by Anonymous Coward on Monday January 25 2021, @05:11AM
https://www.youtube.com/watch?v=uBKdbbQBEJw [youtube.com]
(Score: 2) by driverless on Monday January 25 2021, @06:37AM (5 children)
Engage the auto-repair nanobots. I've watched endless movies documenting the fact that every spaceship has those, so it's really a solved problem.
(Score: 2) by Grishnakh on Monday January 25 2021, @06:14PM (4 children)
What movies are these? I can't recall any.
Honestly, this (nano-machines) is one of 2 big things that I think sci-fi has mostly completely missed, the other being biological immortality. The only interesting treatment of nano-machines I can think of in sci-fi offhand is in the one ST:TNG episode where Wesley accidentally lets some nanites go and they reproduce and evolve, and eventually threaten the science mission being run by some pompous baseball-loving jerk, who uses a phaser to commit nanite genocide. Strangely, nanites never again appear in Star Trek that I know of, even though it would change things in the Federation so much. There's also the "replicators" in the Stargate TV series.
Immortality is the other thing where sci-fi has completely missed the boat. There's already lots of research into aging and senescence, and advances being reported regularly. It's quite likely that in 100 years, aging in humans will simply be eliminated, though it will probably require periodic treatments of some kind. But sci-fi barely mentions anything like this; at most, they'll depict a future society where humans routinely live past 100, or perhaps up to 150.
(Score: 0) by Anonymous Coward on Tuesday January 26 2021, @05:46AM (1 child)
Try the Culture books by Iain Banks.
(Score: 2) by Grishnakh on Tuesday January 26 2021, @05:18PM
Books aren't movies.
(Score: 2) by driverless on Tuesday January 26 2021, @07:41AM (1 child)
Almost every SF movie involving spaceships/space battles has autorepair systems, either ones that function so that any combat/asteroid damage can be shrugged off and the subplot involving the hero and the heroine's sister to develop, or ones that eventually fail so the hero can do a spacewalk and save the ship. The few that don't have autorepair systems are so the hero can do the spacewalk directly without having to spend precious onscreen seconds worrying about the autorepair systems failing.
(Score: 2) by Grishnakh on Tuesday January 26 2021, @04:55PM
I'm sorry, I don't remember any spaceship sci-fi movies that actually depict or even mention such systems. Of course, it's very likely they would need them because of micrometeorites and of course battle damage, but I just don't remember any specifically showing this to the viewer, or using exposition to inform the viewer of their existence. Maybe I've forgotten.
(Score: 2) by sfm on Tuesday January 26 2021, @02:06AM
*** $10 in Flex Tape could knock that out right quick. ***
That may actually help with the leaks, but not so much with
the structural integrity.
(Score: 0) by Anonymous Coward on Monday January 25 2021, @02:57AM (5 children)
so drill some holes to stop them?
what could possibly go wrong
(Score: 2) by Rosco P. Coltrane on Monday January 25 2021, @03:17AM (1 child)
Nothing, if you plug them rightaway.
(Score: 0) by Anonymous Coward on Monday January 25 2021, @09:05PM
Plug them with runaway instead.
(Score: 4, Informative) by Anonymous Coward on Monday January 25 2021, @03:56AM (2 children)
Cracks grow because the tip of the crack is under more stress than the material can take. Drilling a hole at the right spot distributes that stress over a much larger area. Try it with cellophane. Once it has a nick in it the break will just run to the other side. But if you carefully punch a smooth hole in it and then tear so that the crack runs into the hole, suddenly you are back at nearly full strength to start another tear.
(Score: 2) by MIRV888 on Monday January 25 2021, @07:45AM
He's not wrong. Routinely used in aircraft maintenance.
(Score: 2, Funny) by Anonymous Coward on Tuesday January 26 2021, @04:10AM
Idiots will read this as "cellphone" and not "cellophane"...don't be surprised to read about someone drilling holes in their iPhones and complaining that you're wrong!
(Score: 0) by Anonymous Coward on Monday January 25 2021, @06:50AM (1 child)
Worth mentioning is that this is from a few moths ago, and that the leak associated with it is 1/1000 of what is considered 'a problem'.
Still doesn't exactly help you sleep at night...
(Score: 3, Interesting) by FatPhil on Monday January 25 2021, @02:08PM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves