Space In General

Speaking of Starships. Unfortunately not going to fly while I'm here, but it is what it is. I'll come back for the first launch of the full Starship SN20 / Booster #3 orbital launch in a few months...

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And fuel tanks.

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Overpressure notice is out for possible static fire tomorrow, I'll be heading to South Padre Island to see whatever I can. Should be able to hear it too. A flight TFR has also been posted for Friday, though my confidence is low considering it will be really windy that day.

 
Must have an insane motor on it to get the required lift.

Seems it's a 350W motor :lol:

Although it looks pretty tiny, each blade is two feet long - so about four feet wingspan - and the angle on them is super aggressive. They spin at 2,500rpm, which is pretty much drone speed despite each rotor being about 20 times the size of your average drone's!

Of course it doesn't need much to beat Martian gravity, but with 1% atmosphere it needs to shovel a lot of air to even do that. Can't wait to see it change direction.

I suppose with less air comes less drag, so turning big blades at high angles may not be so difficult.
 
I suppose with less air comes less drag, so turning big blades at high angles may not be so difficult.

The main issue is how fast it has to go just to get off the ground. There's almost nothing for the wings and the blades to work against. Even the most advanced jet fighters probably couldn't take off from the Martian surface, and if you tried to launch them mid-air from a high altitude they could probably glide for a little bit but would eventually nose dive into the ground with little to no ability to even turn. Someone's tried to cover this hypothetical scenario before:

https://what-if.xkcd.com/30/
 
The main issue is how fast it has to go just to get off the ground. There's almost nothing for the wings and the blades to work against. Even the most advanced jet fighters probably couldn't take off from the Martian surface, and if you tried to launch them mid-air from a high altitude they could probably glide for a little bit but would eventually nose dive into the ground with little to no ability to even turn. Someone's tried to cover this hypothetical scenario before:

https://what-if.xkcd.com/30/

Seems like a good case for a helicopter.
 
It's been said flying the lower atmosphere on Mars is like flying 100,000 feet in altitude on Earth.

Record altitude for rotary aircraft on Earth: 42,500 feet.

SA 315B Lama

An SA 315B Lama over Mt. Lauberhorn


Record altitude for fixed wing propeller craft: 96,863 feet.


NASA Helios Prototype in flight



Honorable mention:
Record for crewed, propeller-driven piston engine biplane: 56,850 feet.

Ca 161

Role High-altitude experimental aircraft
Manufacturer Caproni
Designer Rodolfo Verduzio
First flight 1936
 
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It's been said flying the lower atmosphere on Mars is like flying 100,000 feet in altitude on Earth.

It'd be like starting up there. Different set of challenges than starting in conditions that do not exist anywhere on mars and transitioning to something more like mars.

Edit:

https://theconversation.com/so-a-helicopter-flew-on-mars-for-the-first-time-a-space-physicist-explains-why-thats-such-a-big-deal-159334
Testing the craft on Earth required a pressurised room, from which a lot of air would have been extracted to emulate Mars’s atmosphere.

https://theconversation.com/so-a-helicopter-flew-on-mars-for-the-first-time-a-space-physicist-explains-why-thats-such-a-big-deal-159334
There are two main ways Ingenuity was able to overcome the hurdles presented in Mars’s atmosphere. Firstly, to generate lift, the two rotors (made from carbon fibre) had to spin much faster than any helicopter’s on Earth.

On Earth, most helicopters and drones have rotors that spin at about 400-500 revolutions per minute. The Ingenuity’s rotor spun at about 2,400 revolutions per minute.

It also has a distinct aircraft-to-wingspan ratio. While Ingenuity’s body is about the size of a tissue box, its blades are 1.2m from tip to tip.

A 4 foot blade spinning at 40 times per second is pretty fun. That's actually really fast, I'm looking at helicopter blades, doesn't cut it. Aircraft propellers don't usually spin that fast, a Cessna's propeller is similar and spins at similar speeds. Most aircraft seem to drive their propellers slower to avoid breaking the sound barrier at the tip.

Seems it's a 350W motor :lol:

Although it looks pretty tiny, each blade is two feet long - so about four feet wingspan - and the angle on them is super aggressive. They spin at 2,500rpm, which is pretty much drone speed despite each rotor being about 20 times the size of your average drone's!

Of course it doesn't need much to beat Martian gravity, but with 1% atmosphere it needs to shovel a lot of air to even do that. Can't wait to see it change direction.

Now that I think about it, 350W motor pushing a 4 foot wingspan at 2,400 rpm makes the extremely low drag setting super obvious.
 
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A 4 foot blade spinning at 40 times per second is pretty fun. That's actually really fast, I'm looking at helicopter blades, doesn't cut it. Aircraft propellers don't usually spin that fast, a Cessna's propeller is smaller than that and spins at similar speeds. Most aircraft seem to drive their propellers slower to avoid breaking the sound barrier at the tip.
On my balsa, paper and plastic model rocket, fins 2.3" long, I'm getting estimated spin rates of >240 rpm. This is almost immediately, starting from near zero at apogee. This is an experimental backslider with horizontal spin recovery, attempting to establish evidence of the Magnus Effect in a model rocket.
 
The main issue is how fast it has to go just to get off the ground. There's almost nothing for the wings and the blades to work against. Even the most advanced jet fighters probably couldn't take off from the Martian surface, and if you tried to launch them mid-air from a high altitude they could probably glide for a little bit but would eventually nose dive into the ground with little to no ability to even turn. Someone's tried to cover this hypothetical scenario before:

https://what-if.xkcd.com/30/

Another way to look at it is weight. On Earth in order to fly, aircraft end up within certain ranges of wing loading (weight/wing area). The air on Mars is about 170 times thinner than Earth, so in order to fly an Earth based design, you'd need it to be 170 times lighter or have 170 times as much wing. Or you could do a little of both and have 1/13th the weight and 13 times the wing area.

For fun I took a high altitude U-2 spy plane and scaled the wings to generate the same lift that they do on Earth:

unknown.png

Or if you were trying to fly a small single seat aircraft that weighs 2000 lbs, you'd need to bolt on wings comparable in size to those of a light airliner, about 100 ft in span. In both cases though, even if you look past the ridiculous wings, there are some other issues, like the horizontal stabilizers being within the wing chord. Don't expect much pitch control.

Then there is another issue that prevents you from just scaling aircraft, which is the low density results in a small Reynolds number. This can drastically change the performance of airfoils, and a wing design that works well on Earth might find itself prone to stalling on Mars.
 
From today's edition of spaceweather.com:

AURORA 'DUNES' SIGHTED OVER CANADA: Auroras still have the capacity to surprise. On April 16th, Matthew Wheeler, an experienced aurora-watcher in Robson Valley, British Columbia, saw a green glow forming in the north--then he noticed something odd. "Horizontal lines caught my attention," he says. "There appeared to be ripples in the aurora."

This video captures 20 minutes of their dynamics:


These are "dunes," a newly recognized form of aurora named after their resemblence to desert sand dunes.

A team of researchers first explained them in a paper published just last year. Dunes are a "mesospheric bore"--a type of atmospheric gravity wave that springs up from Earth's surface and gets caught in a thermal waveguide ~100 km high. When solar wind particles rain down on the bore, they illuminate its rippling structure.

bore_strip.jpg


Sky watchers in the Arctic have been seeing dunes for years without understanding what they were. A breakthrough came on Oct. 7, 2018, when multiple groups photographed dunes from widely separated locations in Finland. Triangulation revealed the dunes to be ~100 km high with a pure, monochromatic wavelength of about 45 km.

This is a new field of study with potential for discovery. Monitoring aurora dunes may reveal previously hidden waves and waveguides at the boundary between Earth and space. Have you seen a dune? Submit your photos here.
 
For Collins and the five [successful] Command Module pilots after him, they experienced something no other human before or since has ever experienced, may not even be able to properly comprehend. As the Command Module swings behind the moon in its orbit, he was (they were) cut off entirely from ALL OF HUMANITY. Yes, it was just a few minutes at a time, but while back there behind the far side, they were completely isolated... no radio, no visible Earth, no contact with anyone, even their fellows on the moon.

I was 12 years old for Apollo 11, and when that was described on TV, it scared the bejeezus out of me! How can anyone go through that?!?!?
 
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For Collins and the five [successful] Command Module pilots after him, they experienced something no other human before or since has ever experienced, may not even be able to properly comprehend. As the Command Module swings behind the moon in its orbit, he was (they were) cut off entirely from ALL OF HUMANITY. Yes, it was just a few minutes at a time, but while back there behind the far side, they were completely isolated... no radio, no visible Earth, no contact with anyone, even their fellows on the moon.

I was 12 years old for Apollo 11, and when that was described on TV, it scared the bejeezus out of me! How can anyone go through that?!?!?
Sounds kind of appealing.
 
The FAA has approved the flight of SN15, as well as SN16 and SN17. (first time they have done multiple at once) And as I type this the flight termination system is being installed. However I do not believe they will fly on Friday, the weather is not good. If things change I will post stream links...

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A TIMELINE OF GREAT AURORA STORMS: Imagine living in Florida. You'll never see the Northern Lights ... right? Actually, the odds may be better than you think. A new historical study just published in the Journal of Space Weather and Space Climate shows that great aurora storms occur every 40 to 60 years.
Extreme solar storms are more frequent than previously thought. From today's edition Spaceweather.com:


"They're happening more often than we thought," says Delores Knipp of the University of Colorado, the paper's lead author. "Surveying the past 500 years, we found many extreme storms producing auroras in places like Florida, Cuba and Samoa."



This kind of historical research is not easy. Hundreds of years ago, most people had never even heard of the aurora borealis. When the lights appeared, they were described as "fog," "vapors", "spirits"--almost anything other than "auroras." Making a timeline 500 years long requires digging through unconventional records such as personal diaries, ship's logs, local weather reports--often in languages that are foreign to the researchers.

"We defined a 'Great Storm' simply as one in which auroras were visible to the unaided eye at or below 30 degrees magnetic latitude," says Knipp.

Visual sightings were key. The human eye is a sensor we've had in common with observers since the beginning of recorded history. Pre-modern scientists didn't have satellites or magnetometers to measure solar storms, but they could look up at the night sky. In all, Knipp's team tallied 14 examples of storms where many people saw auroras within 30 degrees of the equator.

"There may be more," she notes. "For example, I am aware of a low latitude event that occurred between February and April 1648. It's not on the timeline, though, because we haven't yet been able to pin down the date."


Above: An eyewitness sketch of red auroras over Japan in mid-September 1770. [ref]

Look at the timeline again; there's a whole cluster of sightings in Sept. 1770. "The Great Storm of 1770 appears to be a 500-year event," says Knipp. "There were low-latitude auroras for 9 nights in a row."

During the 1770 storm, extremely bright red auroras blanketed Japan and parts of China. Captain James Cook himself saw the display from the HMS Endeavour near Timor Island, south of Indonesia. Knipp's colleague Hisashi Hayakawa (Nagoya University) has found drawings of the instigating sunspot; it is twice the size of the sunspot that caused the infamous Carrington Event of 1859. Knipp's timeline suggests that this was not "just another Great Storm"; something exceptional happened in 1770 that researchers still don't fully understand.

Today's senior space weather researchers were taught in school that Great Storms are rare. The Carrington Event was long thought to be a singular event, alone in the historical record. Recent studies are finding otherwise. Just last month Jeffrey Love of the US Geological Survey published a paper in Space Weather showing that extreme geomagnetic storms recur every ~45 years or so--a result in accord with Knipp's. He used completely different techniques (extreme value statistics and magnetometer records) to reach a similar conclusion.

The last Great Storm in the timeline occurred 32 years ago. Soon, it will be time for another. Stay tuned.
 
SN15 flight attempt for today has been scrubbed.

SN16 is being stacked currently, but all of the 24/7 live stream feeds are down due to a power outage.
 

So theoretically we could get 3D photogrammetry of good sized portions of Mars's surface via drone within the next couple decades. It takes a lot of cameras to do that - currently entire Cessnas worth of cameras to cover any decent distance - but it could be done. The fact that they're flying a drone right now is honestly so funny I'm not sure I'm grasping how rad it is. Of course a stupid drone would be the first thing to buzz around and annoy the local fauna lol. Did they get permission from the FAA to fly that damn thing?
 
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SN15 flight is looking GREAT for Tuesday. All approvals are in, weather looks great, testing notice received by residents. I'll post stream links when available.

 
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