Spy sats: yes!, please.

I am happy that you use metric system for the description of the video.

The 2017, Super Low Altitude Test Satellite (SLATS) or Tsubame using Ion engine propulsion has demonstrated a sustained orbit of 167 kilometers or about 104 miles for a duration of one week.

Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) operated by ESA orbit at around 250 km and to do so, they had ion thruster continuously firing to maintain that extreme low altitude. Although some satellites and spacecraft had been orbiting as low as below 150 km, they only doing it briefly. Cheers : )

there is research by ESA to collect the left air particles, decelerate them and use as fuel of Ion drives. Unfortunately I have no Idea at what altitudes they aim

GOCE flew at the edge of the atmosphere, and was kept in orbit by an ion thruster. To quote the ESA website, 'Launched on 17 March 2009, ESA's Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission was the first Earth Explorer mission in orbit.' GOCE operated until late October 2013, when its fuel was exhausted, and it de-orbited on 11th November 2013. The craft was somewhat streamlined to reduce the effects of atmospheric drag. There are plans for another launch. You might want to make a video about this interesting satellite.

Hi Lei, it would be really cool to see a video breaking down the elements of a modern Spaceport. Thanks!

The Karmen line is simply the point at which there isn't enough air to provide useful lift to an aircraft in order to stay up. At that altitude, your horizontal speed has to be so high (from the thrust of your engines) that wings don't make a difference any more.

Thanks for doing a well organized presentation, as usual!

I recently read a study proposing something like 54 km as the new boarder to space. The reasoning is, according to the person conducting the study, that is the statistically lowest altitude a satellite can still orbit before fully reentering. He said there were a few examples of satellites reentering that did at least two full orbits at that altitude, but I don't think that constitutes a better definition to the edge of space. Food for thought. Anyway, thanks for the video, and keep up the good work!

Love to hear more about the spy satellites Lei

That was very interesting Lei, well done.

Check your math. I enjoy the videos but often get hung up on silly mistakes like you saying 350 is 1/10th of 35,000. Dude! You can fix these kinds of things to take your channel to the next level

Satellites don't fly, they are constantly falling down to the planet they're orbiting. It's just that they go so fast, that they don't hit the planet.

Great video, very clear and easy to understand explanation for non-scientists. Good job

Your vids are so well made the quality is unbelievable keep up the great quality videos 👍

I would love to see a video on spy satellites! You have such interesting vids. TY Lei;)

Awesome vid bro, very informative, thanks.

A great channel in the making.

Love the channel,

Communication satellites fly that high in order to stay in a geocentric orbit (23h, 56min, 4sec) in order to stay anove the same place in the earth, so people on the groud would have constant communication without changing the dish's orientation (for example satellite TV)

Minor correction - New Horizons didn't "end its nine year journey successfully" - it's still going! On Jan 1, it will pass Kuiper Belt object (486958) 2014 MU69 (which will get a "real name" after the flyby.) It is even scheduled to pass 1/3 the distance than it did in its pass of Pluto!

Interesting subject. I recall reading that the heaviest satellite launches on ULA's Delta-4 heavy platform were all coincidentally classified military payloads. I guess all that camera glass weighs quite a lot!

I should point out that the hubble telescope is a distant cousin to the KH-11 keyhole satellites, being designed and built by the same companies between the late 80's and 90;s, the hubble of course was optimized for looking outwards, with larger instrument bay and was made to be serviced. It still features the same basic design and 2.4 meter telescope. You may not have heard but the national reconnaissance office gifted a pair of unneeded keyholes (minus the CCDs and classified electronics) to NASA in 2012. These 'obsolete' observatories were made much later than the hubble and are somewhat more advanced, despite still having the same 2.4 meter aperture they have a secondary mirror allowing wider field of view as well as more focused zoom. Fitted with more modern scientific equipment they should be vastly superior to the hubble, especially if launched as a pair for stereoscopic observation. Though NASA probably doesn't have the budget for this. The WFIRST sattelite is planned using one of these satellites, as long as funding doesn't get cut it should launch in a few years.

Excellent, Learned a lot. Cool man!

Nano-satellites, and they are an intriguing trend. Nono satellites represent are small m, as small as a cube a few inches square. Nations line Japan have been launching these; they are primarily research satellites. The advantage is the lower cost not just to produce them, but also the lower cost to put them into orbit. Because nanos are so small, they incur less aerodynamic drag at their very low orbits. Akso, there are now electronic propulsion systems capable of boosting nano-satellites to maintain minimal orbiting parameters. Separately, lowest satellite orbit ever was achieved by larger tyke satellite that skimmed the Earth with an 80 mile perigee while having a much larger apogee (elliptical orbit). It completed one revolution around the Earth before reentry.

Van Allen said 'NOPE' to moonlanding...

No, we haven't explored every corner of our solar system, that would be like saying we visited 8-9 landmarks under the ocean thus have explored every corner of the seas. There's a LOT of space out there and all our satellites have only traversed a tiny fraction of the total area that encompasses our solar system, but yes we've visited most of the major landmarks, not all the moon's yet, nor the belts, ort clouds or intergalactic visitors (omuamua).

Your videos are always well created and interesting

I love this channel i hope this channel gets a million subs soon

Apollo 15-17 achevied an even lower 'parking' orbit at ~170km before trans lunar injection. These parking orbits are not stable in the long term. It should also be noted that failing/uncontrolled objects like Tiangong-1 made a few orbits at even lower altitudes before reentry.

There's currently a development of a satellite with scramjet engine. The engine will use solar power as it's energy source. Soon, satellite can fly as low as 80 km above the Earth.

Incredible content. 👍

I am very thankful to you for giving valuable information about very hard and difficult technical subject in very simple way

Very nice video, thanks

I spend time watching ISS passes, have seen many Starlink trains, and always looking for other satellites. I’ve wondered about lowest possible orbits since witnessing a dim satellite moving west to east at an apparent speed I’m guessing was 4-6 times faster than ISS passes. No idea if it was something in a stable orbit, or if it was something destined to re-enter shortly. If it was in an eccentric orbit, and seen at perigee, it could have been quite low so apparent speed would appear much faster. Do you have any examples of things that can be seen demonstrating very low altitudes? Assuming a near circular orbit, it seems one could calculate a satellites altitude by by rigging a movable fixture / framework with a couple glow in the dark strings stretched across it, parallel and at a distance from ones eye that can remain fixed. Measure the time it takes for ISS to cross between strings, check time for others to do the same, and do a little math.

You forgot one of the main factors to why ISS is placed in its current orbit and its how high the Space Should could send useful payloads back in the day when the station where build. They could only reach so high while carrying the components that made up the station. The exeption is Hubble whom was placed in a much higher orbit but that took some extra effort to get there when they build and repaired that telescope. Johan.

A video about the spy satellites is definitely welcome 👍

Yes, please do a video on spy satellite 🛰 I was blown away when I was told that the Hubble telescope has design features and technology which most likely came from spy satellites

More and more bro good job and waiting for spy satellites

I'd love a video on spy satellites, very interesting topic!

Great video

I wonder if SpaceX's lower StarLink satellites would use air breathing ion thrusters to keep their orbit from decaying.

Hi, Lei!

Really interesting!!!

Yeah! Videos about spy satellites would be awesome! They also do not deviate from this channel's main interest...

Superb video, i want the video on spy satellites😊

Don't forget dron military spaceship like X-37-B, OTV. How many spy and military satellites are there today? I think that there are thousands, and some U.F.O cases are these vehicles sometimes. Thanks for this video. Have you got a nice weekend!

Would love to see more videos on spy sats. Speaking of spy sats, I would interested to see another follow up video on Zuma. Its surprising how quick that story got dropped by the media considering the enormous costs involved.

*....Great Video!! Can you please send me a Link to a Satellite Orbiting the Earth? I've been searching for myself over 22 years and I can only find CGI Cartoons of Satellites Orbiting the Earth.. Any information or help would be greatly appreciated.. Thank You....*

Hi Lei! Have you heard about atmosferic fed ion thrusters which will allow satelites to spend long time much lower than 200km?

Got a question Can we make an object Orbit as low and long as possible/forever In a air-less perfect sphere/spheroid earth?

Let's go for a spy satellite video!!

Yess i would love to watch...😀

Wouldn't it make sense for low earth orbit satellites to be streamlined to lower their drag coefficient?

What is the lowest possible orbit on a planet/moon without an atmosphere ? Can someone do a 10m orbit on moon (assuming moon a perfect sphere)? (or in other words what is the equation to find out lowest possible orbit of a perfect sphere object in space ? )

Do a video on spy satellites, and also the components and infrastructure of future spaceport so! !

Hi Lei, I love the work you do! Keep it up. Some things I want to point out, your pronouncing Uranus wrong and we haven't explored every corner of our Solar System yet! That would imply that we have checked every single moon, asteroid and comet in our Solar System and that is not the case. But overall amazing job! Can't wait for a video talking about spy satellite and how they reboost their orbits!

How does spy satellites maintain orbit against air resistance ?

Well yes! We surely want to know deep about spy satellites. Please do make a video on it. And mention the America's biggest Intelligence failure as well which occured during May 1998, the Nuclear test in India!

Great video ---------------------------------------- Very interesting

But how do spy Sat maintain orbit since its not possible to carry fuel to do course correction for the entire lifespan of the sat.

Very good ...we need more information about earth orbit...

Okay, a better video after a while

SLATS(thats a satellite from the japapanese space agency) is currently in orbit, lowering gradually and will be flying at an altitude of just 180km's for a certain amount of time next year. see here (currently at stage 5) news.mynavi.jp/article/20171012-slats/images/007l.jpg (not sure if theres a plan like that in english)

Nice video thanks. I appreciate it's ideas you're trying to get across with your graphics rather than specifics, but could you show at least one of them to scale for us geeks?

5:26 is it Fedor?

Nice vide, would be nice to show the correct perspective of earths size to LEO/GEO distance.

More of these videos, please. And thank you for not having those terrible background music productions, like is common place in netvideos.

also any internet based satellites in teh leo orbit can get close to 200. I know I thought was a communications statellite for a foreign customer of spaceX was going lower but might be wrong about that. Again we have to much garbage up there right now

So, when will that video of spy satellites be available? Also, have you found information about any satellites with an altitude, say, 160km? ;)

Spy secret satellites would be very interesting

Yes very interested

There’s a satellite with an air breathing ion engine being developed, I’m pretty sure it will fly below the Karman line, it will fire its engine non stop to stay up. You should do a video on that

Yeah we r really interested in info about spy satellites... Waiting for upcmg video....

But what was the altitude of the parking orbit of the Saturn V?

please do one about the spy satellites

Just a small correction, we haven't literally explored the entire solar system. Far from it. Awesome video!!!!!!!

Yes more Spy sats!

There's also a new form of ion engine being developed by ESA, instead of using xenon it uses the Earth's atmosphere, it can be used at very low altitudes. You can read more about it here. www.esa.int/Our_Activities/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster

Make video on orbital mechanics

Yessssssssss plz make video on spy setallite....plz

Spy sats 😍

When did we explore the Oort Cloud?

I would have loved some relatively accurate orbits..even though not too scale but 400km and 340km looks like 2000km and 400km

So how many kilometers?

Oh I wouldn't say that we have explored every corner of our solar system. Uranus and Neptune have only gotten a brief fly by and the sun itself still leaves us with mysteries which especially Parker Solar Probe is going to solve within the next decade. But we do certainly know a low more about the solar sytsem than 100 years ago.

What is the orbiting speed at 200km

Do one on the Black Knight satellite

Brand new subscriber here, spy satellites please!

The lower the orbit of a satellite, the faster it has to be, right? I was kinda expecting this fact as a part of this video (just because of thumbnail and name), because the max. speed could also be a limit to how low a satellite could fly I guess.. or is the "drag-problem" much more significant than the "max. speed-problem" ? maybe you could do an extra video on this topic or get to it on the spy satellite video. thanks!

Yes we need spy satellite video

It would be cool if we could see all the satellites once a year they should turn on a light or something

Yes, i wish to know more

Even lower orbits would be parking orbits of spacecraft going to GTO or those who leave earth. They can go as low as 160 km because they only stay in that orbit for up to an hour before they do their apogee raise burn or their escape burn.

I know the internation space station is always falling towards the earth because it is in earths atmosphere

Yes please

Good video, however there were 4 missions to Saturn. Pioneer 11, Voyagers 1 and 2, and Cassini.

A video on Spy satellites please!......

Ya Of course! About spy stattelites!