APOD: Verona Rupes: Tallest Known Cliff in... (2011 Apr 04)

[APOD Robot]

Verona Rupes: Tallest Known Cliff in the Solar System

Explanation: Could you survive a jump off the tallest cliff in the Solar System? Quite possibly. Verona Rupes on Uranus' moon Miranda is estimated to be 20 kilometers deep -- ten times the depth of the Earth's Grand Canyon. Given Miranda's low gravity, it would take about 12 minutes for a thrill-seeking adventurer to fall from the top, reaching the bottom at the speed of a racecar -- about 200 kilometers per hour. Even so, the fall might be survivable given proper airbag protection. The above image of Verona Rupes was captured by the passing Voyager 2 robotic spacecraft in 1986. How the giant cliff was created remains unknown, but is possibly related to a large impact or tectonic surface motion.

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[Ann]

I'm thinking of Miranda as the "L moon", because it has a huge "L" clearly displayed on its surface. (And by the way, who said that square shapes don't exist in nature? Not only does Miranda has this huge "L", but the letter also sits inside a huge, slightly lopsided but mostly square shape!)

If Miranda had been photographed before it was named, it would surely have been given a name beginning with an L. Or maybe we should call it Ella?



Ella-Miranda, the square? The cliffhanger?

Ann

[tnzkka]

What struck me most is the fact that you land at the foot of the Miranda-cliff with about the same speed as a free-faller would have on Earth (the so called terminal velocity http://en.wikipedia.org/wiki/Terminal_velocity )

[Amir]

I believe there would be no terminal velocity on Miranda. the objects won't be traveling through any fluid or medium.
because of lack of the atmosphere, there is no reason for being stopped at terminal velocity.

[orin stepanek]

Miranda is one really scarred up moon!

[nstahl]

Interesting about the "L". Maybe it once had visitors from a planet whose name started with L, or a star such as La Superba.

Or just something named Larry or Lenore.

[Chris Peterson]

I believe there would be no terminal velocity on Miranda. the objects won't be traveling through any fluid or medium.
because of lack of the atmosphere, there is no reason for being stopped at terminal velocity.

Correct... but I think you may be misunderstanding the previous comment. The coincidence is that if you jump from this cliff on Miranda, you'll hit the bottom at about the terminal velocity limited speed of any long fall on Earth.

[neufer]

Approaching the 2007-12-07 equinox Miranda produced
brief solar eclipses over the center of Uranus.

Two households, both alike in dignity,
In fair Verona, where we lay our scene,
From ancient grudge break to new mutiny,
Where civil blood makes civil hands unclean.
From forth the fatal loins of these two foes
A pair of star-cross'd lovers take their life;
Whose misadventured piteous overthrows
Do with their death bury their parents' strife.
The fearful passage of their death-mark'd love,
And the continuance of their parents' rage,
Which, but their children's end, nought could remove,
Is now the two hours' traffic of our stage;
The which if you with patient ears attend,
What here shall miss, our toil shall strive to mend.

Art Neuendorffer
You have the right to remain silent. Anything you say can and will be used against you in a court of law. You have the right to speak to an attorney. If you cannot afford an attorney, one will be appointed for you. Do you understand these rights as they have been read to you?

[owlice]

She wants wit that wants resolved will
To learn her wit to exchange the bad for better.

Darn it, neufer! I'd had "Officer Krupke" in my head for days and days, and it was finally gone... until I read your post. Thanks. Thanks a lot!

[Beyond]

Owlice, try just focusing on 'the thrill-seeking adventurer' in todays Apod explanation. THAT may help you get officer what's his name out of your head.
I think the co-captains of this cyber-ship have a lot of fun putting the 'explanations' together.

[neufer]

She wants wit that wants resolved will
To learn her wit to exchange the bad for better.

Darn it, neufer! I'd had "Officer Krupke" in my head for days and days, and it was finally gone... until I read your post. Thanks. Thanks a lot!

• You need an analyst's care.

Click to play embedded YouTube video.

[owlice]

hahahahahahaha!!! I am sooooooo not clicking on that!!

[JohnD]

Wow! Neufer nods!
Miranda is in the Tempest!

But to continue with R&J:
Balcony scene, set on a Moone of Uranuss:

Romeo, Romeo, wherefore art thou Romeo?
(Silence)
I SAID, ROMEO, ROMEO, WHEREFORE ART THOU ROMEO!
(Silence)
I SAID, ROMEO, ROMEO, WHEREFORE ART THOU ROMEO!

(He's a long way down from that balcony)

[C0ppert0p]

The original JPL caption for that photograph reads, "...The fault may be 5 km (3 mi) high, or higher than the walls of the Grand Canyon on Earth.
When and or why did the estimate change to 20 km?

[neufer]

The original JPL caption for that photograph reads, "...The fault may be 5 km (3 mi) high, or higher than the walls of the Grand Canyon on Earth.
When and or why did the estimate change to 20 km?

The original conservative estimates of 5 to 10 km high seem to have been now replaced by 20 km high.

No doubt there are good reasons for the change.

[Amir]

I believe there would be no terminal velocity on Miranda. the objects won't be traveling through any fluid or medium.
because of lack of the atmosphere, there is no reason for being stopped at terminal velocity.

Correct... but I think you may be misunderstanding the previous comment. The coincidence is that if you jump from this cliff on Miranda, you'll hit the bottom at about the terminal velocity limited speed of any long fall on Earth.

oops! yeah, I thought it meant it's interesting that terminal velocity would make us travel at the same speed no matter where we jump... earth or miranda!
thanks!

[JohnD]

Amir,
I fear that's still the wrong interpretation.
Here on Earth, a human body falling from a 'reasonable' height, which might be taken as low enough not to need oxygen, will reach a 'terminal velocity', when the acceleration under gravity becomes equal to the decelleration of aerodynamic drag. Falling froma greater height, where the atmosphere is thinner, will allow the body to reach a higher velocity. A recent attempt to drop from an extreme height, when it was predicted that the faller might approach the speed of sound (another variable with air density), was aborted when the ballon flew off without the capsule (Oooops!)

On atmosphereless Miranda, nothing will slow the faller's inexorable acceleration under gravity, except of course final contact with the surface. There is no terminal velocity except zero, in a very,very thin layer of tissue on rock or ice. That Terran terminal velocity and the velocity that a falling body would reach down this cliff are the same is a coincidence. It's not even interesting, because it has no significance.

John

[neufer]

I am sooooooo not clicking on that!!

You just have to come up with some new lyrics:

<<Thomas Bishop joined the Massachusetts Infantry before the outbreak of war and compiled a popular set of lyrics titled "John Brown's Body", which became one of his unit's walking songs. Julia Ward Howe heard this song during a public review of the troops outside Washington on Upton's Hill, Virginia. Staying at the Willard Hotel in Washington on the night of November 18, 1861, Howe awoke with the words of the song in her mind and in near darkness wrote the verses to the "Battle Hymn of the Republic". Of the writing of the lyrics, Howe remembered:

I went to bed that night as usual, and slept, according to my wont, quite soundly. I awoke in the gray of the morning twilight; and as I lay waiting for the dawn, the long lines of the desired poem began to twine themselves in my mind. Having thought out all the stanzas, I said to myself, 'I must get up and write these verses down, lest I fall asleep again and forget them.' So, with a sudden effort, I sprang out of bed, and found in the dimness an old stump of a pen which I remembered to have used the day before. I scrawled the verses almost without looking at the paper.>>

[Chris Peterson]

I fear that's still the wrong interpretation.

I don't think so.

That Terran terminal velocity and the velocity that a falling body would reach down this cliff are the same is a coincidence. It's not even interesting, because it has no significance.

Something doesn't need to have any particular physical significance to be interesting! The discussion in the caption of leaping off of cliffs certainly brings to mind the idea of doing the same on both Earth and Miranda, and therefore makes the coincidence of similar landing speeds interesting.

[DavidLeodis]

Its fascinating that the two Voyager probes are still moving away and also still transmitting informtion. I wonder what will eventually happen to them? They are each like an old friend now. I felt like I'd lost a friend when Spirit Rover died on Mars and will do so again if the Voyager probes die during my lifetime.

[neufer]

<<Lover's Leap (sometimes spelled as Lovers Leap), is a toponym given to a number of locations of varying height, usually isolated, with the risk of a fatal fall and the possibility of a deliberate jump. Legends of romantic tragedy are often associated with a Lovers' Leap.

The Lover's Leap in Hawk's Nest State Park, West Virginia, has a drop of 178 m from a high bluff overlooking the New River Gorge. The promontory was named "Lover's Leap" by settlers, and has acquired an urban legend involving two young Native Americans from different tribes.

Dovedale in the Peak District in the UK has a limestone promontory named Lover's Leap reached by a set of steps built by Italian prisoners of war captured in the Second World War. The local legend is that a young woman believed her lover had been killed in the Napoleonic war, so she threw herself off the top of the promontory. Later her family found out that her boyfriend was alive and well.

Blowing Rock Mountain, North Carolina, has a similar legend of a young lover leaping from the cliff and instead of plunging to his death, is saved. In this version the lover is saved by the blowing wind which sends him back into the arms of his sweetheart.

Wills Mountain has a Lover's Leap overlooking "the Narrows" at Cumberland, Maryland, USA. It is 504 m above sea level and made up of oddly squared projections of rock from its top all the way down to U.S. Rte. 40.

Jamaica has a Lover's Leap 520 m above the Caribbean Sea. Lovers' leap is named after two slave lovers from the 18th century, Mizzy and Tunkey. According to legend, their master, Chardley, liked Mizzy; so, in a bid to have her for himself, he arranged for her lover, Tunkey, to be sold to another estate. Mizzy and Tunkey fled to avoid being separated but were eventually chased to the edge of a large steep cliff. Rather than face being caught and separated, the lovers embraced and jumped over the cliff.>>

[pferkul]

How difficult would it be for a climber to scale this cliff? Consider the specific potential energy change, (g h) where g is acceleration due to gravity and h is the height.

For the cliff on Miranda, this is (0.079 m/s2)(20000m) = 1580 J/kg.

On Earth, this would be equivalent to an elevation change of (1580 J/kg) / (9.81 m/s2) = 160 meters.

Easy! (Except for the detail about being in a frigid, airless vacuum, etc.)