The thread for space cadets!

[hobbsyoyo]

This Hobbs' post needs moar!

https://www-istp.gsfc.nasa.gov/Education/wtether.html


Hehe, boosting an orbit using purely electricity!
How crazy is that?
A shame the magnetic force on the wire/tether causes deorbiting, or it would be a great way to get free electricity.



My goodness, a 12.5 mile or 20117 meters long cable.

Assuming low earth orbit and an orbit crossing the magnetic field lines at a 90 degree angle, we can can calculate the voltage across the wire if we assume 25 to 65 microteslas 20 miles up for the Earth's magnetic field strength.
https://en.wikipedia.org/wiki/Earth's_magnetic_field

10:00 at the Khan academy video
https://www.khanacademy.org/science...wire/v/magnetism-12-induced-current-in-a-wire

20,117 meter cable * 7800m/s orbital velocity * 0.000045? Teslas field strength = 7061 Volts of potential difference across the whole wire?


Huh, reality was 3500 Volts.
Perhaps the cable length wasn't all there, or perhaps the orbit angle wasn't perfectly perpendicular to Earth's magnetic field, or the Earth's magnetic field up there was less than 45 microteslas?



19,700 meter cable when it broke.
3500 Volts
STS-75 had an orbital period of 90.5 minutes, so 7727 m/s orbital velocity.
Earth's magnetic field was 19,700 * 7727 * x = 3500
x = 23 microteslas?

Could read the paper on it I suppose since actual scientists know a lot more.
The current-voltage characteristics of a large probe in low Earth orbit: TSS-1R results
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/97GL02958


The magnetic force opposing the conducting wire's orbit through Earth's magnetic field?
https://courses.lumenlearning.com/p...gnetic-force-on-a-current-carrying-conductor/

With a constant flow of 1A of current, it would be 1* 19,700 * 0.000023 = 0.4531 Newtons applied to the entire 19,700 meter wire.
1 Newton accelerates 1 kilogram 1 meter per second every second.
Would need to know the mass of the 19,700 meter cable and attached satellite.

Only need to lower the orbital velocity from 7727m/s to 7637m/s to deorbit like the shuttle, a loss of 90m/s
https://space.stackexchange.com/que...enough-to-commit-the-space-shuttle-to-landing

Call the cable+satellite 518kg
https://space.skyrocket.de/doc_sdat/tss-1.htm

It should lose 90 meters per second in orbital velocity and start crashing into Earth after 518 / 0.4531 * 90 = 102,891 seconds or 28.5 hours conducting 1 Amp.
A bit over a day to crash.

No idea if these calculations are even close.
In reality, the thing stayed up there for over 3 days at least.
Can't seem to find how long it stayed up in Earth's orbit.


**Edit**
Sigh, it was 0.48A, not 1A
https://www.americaspace.com/2014/0...cond-flight-of-the-tethered-satellite-part-2/
=========================

I also want to plug the spinning wheels that make it so satellites and spaceships don't spin out of control.

14:25 WTH is that?!
1968 production values

Thanks for sharing. There is a company (Tethers Unlimited) that was founded to pursue and commercialize this technology. They do offer a few products in this vain but have mostly moved on to more 'traditional' space technologies.

Materials limitations and lack of heritage have been big factors against the wide spread of these technologies. Of those factors, heritage is the far larger hurdle - as is so often the case in the space industry. There is a huge in-built tradition against trying new things.

Its magic how much prograde and retrograde bursts (even with small thrust) can impact orbit at right points of orbit.

Spoiler :

Managed to reach 4000 km perfect circle orbit in Orbiter with regular Atlantis Space Shuttle (with big fuel tank still attached ) and manual controls (if don't get nose down quickly enough after start - will get really high but with too slow orbital speed to get around Earth) just by doing short bursts at perigee to get up apogee and at apogee to get up perigee (and oposite way to get down back on Earth, using atmosphere (precise retrograde trust at apogee and can get perigee at altitude you want ) to slow down a little bit before actual entry - going directly into Earth atmosphere from high altitude orbit would be little more unrealistic and dangerous to space ship structure that is designed to do that from 110 km orbit.

Yup. Conversely, non velocity-vector burns are much less impactful, particular inclination changes. I have analyzed missions that wanted to do deep inclination changes and it was easier to launch a second satellite into the new orbit than to shift a satellite from one to the other.

 

[Birdjaguar]

Isn't there a big space event this week?

 

[uppi]

Isn't there a big space event this week?

There is going to be the fly-by of (486958) 2014 MU₆₉ by the New Horizons probe on the 1st of January. That will hopefully result in the first detailed pictures to a Kuiper belt object other than Pluto. Technically it will be next week, but it is going to be the biggest space event in the near future.

 

[Thorgalaeg]

Thanks for sharing. There is a company (Tethers Unlimited) that was founded to pursue and commercialize this technology. They do offer a few products in this vain but have mostly moved on to more 'traditional' space technologies.

Materials limitations and lack of heritage have been big factors against the wide spread of these technologies. Of those factors, heritage is the far larger hurdle - as is so often the case in the space industry. There is a huge in-built tradition against trying new things.

Yup. Conversely, non velocity-vector burns are much less impactful, particular inclination changes. I have analyzed missions that wanted to do deep inclination changes and it was easier to launch a second satellite into the new orbit than to shift a satellite from one to the other.

We KSPians know it very well.

 

[Michkov]

Isn't there a big space event this week?

The Chinese are attempting to land a rover on the Pink Floyd side of the moon on January 3

 

[Cutlass]

 

[hobbsyoyo]

Isn't there a big space event this week?

There is going to be the fly-by of (486958) 2014 MU₆₉ by the New Horizons probe on the 1st of January. That will hopefully result in the first detailed pictures to a Kuiper belt object other than Pluto. Technically it will be next week, but it is going to be the biggest space event in the near future.

If the shutdown is ongoing, you will have to turn to the university partners on New Horizons to get any coverage of the flyby - NASA is shut down for non-critical functions. They will be working the flyby but they won't be able to support press conferences and the like. This new year could have began on such a high note carried over for last, to bad the government is squandering this opportunity to show off the shiny new science.

The Chinese are attempting to land a rover on the Pink Floyd side of the moon on January 3

Go China! Here's hoping them success.

 

[uppi]

If the shutdown is ongoing, you will have to turn to the university partners on New Horizons to get any coverage of the flyby - NASA is shut down for non-critical functions. They will be working the flyby but they won't be able to support press conferences and the like. This new year could have began on such a high note carried over for last, to bad the government is squandering this opportunity to show off the shiny new science.

I forgot about the silly shutdown and the even more silly rules about it.

 

[Birdjaguar]

Bummer.

 

[Thorgalaeg]

I don't get how a government can be shut down as a lamp whenever the president feels like it.

 

[Imaus]

I don't get how a government can be shut down as a lamp whenever the president feels like it.

It's not whenever he feels like it, it's a budget issue. No budget can be passed meaning that at best the agencies and orgs of the government are working with last year's budget and at worst nothing is being done besides Military functions.

This shutdown is the third or second largest, the largest being Dec 2013 which had 20 days of shutdown. No one has ever seen the government shut down for a month or two....

 

[Michkov]

Odd that the other nations of the planet dont seem to run into that problem.

 

[Cutlass]

Odd that the other nations of the planet dont seem to run into that problem.

Most of the time, we don't either. But then there are Republicans, who want to destroy anything that they can't completely control.

 

[Lemon Merchant]

Moderator Action: Guys, there are a number of political discussion threads. This is a space thread. Need I say more?

 

[Silurian]

Well any way the flyby has been successful.
We have to wait for two years for all the photos of Ultima Thule to be down loaded.

So where next will the probe go.

 

[hobbsyoyo]

Europa is the next flagship mission. It is already booked on a Block 1 SLS flight to help keep that production pipeline open. This will likely just be an orbiter followed by a lander 5 to 10 years afterward.

They also have to race to finish James Webb and another space telescope (WFIRST if I recall correctly) that keep threatening to get cancelled due to incompetence.

Mars 2020 (a Curiosity follow up) looks to be on schedule and on budget and should be able to cache samples for later retrieval and also fly a small helicopter to explore terrain.

 

[Birdjaguar]

Mars 2020 (a Curiosity follow up) looks to be on schedule and on budget and should be able to cache samples for later retrieval and also fly a small helicopter to explore terrain.

You mean a drone?

 

[hobbsyoyo]

Yeah one of the NASA centers (JPL if I recall correctly) got permission to develop an autonomous drone to be launched off the main rover. It's low risk/high reward experimentation and if it isn't ready by launch they can just drop it from the design with no real consequence.

 

[uppi]

Well any way the flyby has been successful.
We have to wait for two years for all the photos of Ultima Thule to be down loaded.

Well, successful in the sense of that it actually was a fly-by and not a crash that would have been very spectacular if anyone had been around to see it. It will take those two years until they can verify that the probe took all the data it was supposed to.

But we don't have to wait too long, the first images should be available very soon (maybe tomorrow?). The first thing they will most likely download is an overview shot of the whole object, which will be good both for PR purposes and for getting an overview to start the scientific investigation.

 

[Cutlass]

How do you fly something on Mars with that little atmosphere?