# Largest delta-v from mechanically stored energy?

The math behind this answer suggests that while the delta-v delivered from hand-throwing an object from the ISS would not produce prompt de-orbit and atmospheric reentry, it would still lower the perhiapsis by tens if not a hundred kilometers (depending on the flexibility of the space suit).

I humorously but quantitatively suggested that a hand-held slingshot device (not the gravitational maneuver of the same name) would be sufficient.

When satellites are deployed from their upper stages, usually some kind of small impulse ensures the separation is clean, well controlled and certain. From the video's I've seen the separation velocities are often of the order of a meter per second. I'm guessing this impulse is often produced by springs or other devices that store mechanical energy.

I'm wondering if mechanically stored energy has ever been used to produce a delta-v substantially larger than this, perhaps 5 or 10 m/s? More?

Question: What is the largest delta-v ever produced in space from mechanically stored energy?

For the purposes of this question, energy stored as a compressed gas, or phase change wouldn't count. The source of energy should be something along the lines of springs or other elastic material held under mechanical stress or rigid body phenomena. Also while I'm primarily interested in intentional events, unintentional events might also apply.

• Maybe consider changing slingshot to something like 'catapult' to avoid confusion with the gravitational assist sort? – Jack Jun 22 '18 at 8:17
• @Jack done, good thinking! – uhoh Jun 22 '18 at 8:33
• Would you consider something like a flywheel disintegrating as "mechanically stored energy|? – Steve Linton Jun 22 '18 at 8:58
• @SteveLinton I hadn't though about unintentional events or mechanical energy stored in that way, but it seems to be close enough. I'll adjust the wording slightly, but if you decide to post an answer, it should be a real, documented event, not just a hypothetical scenario. – uhoh Jun 22 '18 at 9:05
• What about recoil from a space cannon? – GdD Jun 22 '18 at 9:49

If pneumatic pressure counts as mechanical energy, then the winner by far is the "manhole cover in space." In 1957, a nuclear weapon was detonated at the bottom of a mine shaft with a 2,000 lb manhole cover blocking the top of it. It is unknown whether it made it out of the atmosphere or was vaporized, but if did make it out it is the fastest moving object created by mankind.

During the Pascal-B nuclear test, a 900-kilogram (2,000 lb) steel plate cap (a piece of armor plate) was blasted off the top of a test shaft at a speed of more than 66 km/s (41 mi/s; 240,000 km/h; 150,000 mph). Before the test, experimental designer Dr. Brownlee had estimated that the nuclear explosion, combined with the specific design of the shaft, would accelerate the plate to approximately six times Earth's escape velocity.[8] The plate was never found, but Dr. Brownlee believes[9] that the plate did not leave the atmosphere, as it may even have been vaporized by compression heating of the atmosphere due to its high speed.

• Even if it didn't make it out - perhaps, briefly, it was the fastest moving human-made object anyway. – Don Branson Jun 22 '18 at 18:22
• At least, from mechanical energy, and not from electromagnetic energy in the LHC. – Don Branson Jun 22 '18 at 18:23
• Was there any actual evidence of what happened or is this all just theoretical calculations of what could have happened? – Organic Marble Jun 22 '18 at 19:25
• @OrganicMarble - there is evidence that establishes a lower bound for its velocity. Specifically, a high speed camera was pointed at the site where the manhole cover was placed with the intention of tracking its movement. Sadly, it only captured the manhole cover for one frame so you can only really establish a lower bound for its speed rather than an actual velocity or a change in velocity over time. The manhole cover was never found, meaning that it likely either escaped the earth or was vaporized due to air resistance. – Justin Braun Jun 22 '18 at 20:41
• The fifties, when dreaming of nuclear powered street cars was possible. The speed of 66 km/s was not measured and the estimation might be wrong anyway. – Uwe Jun 23 '18 at 15:15