Fastest Spacecraft Ever?!?, Which one is it? |
Fastest Spacecraft Ever?!?, Which one is it? |
Jan 24 2006, 08:43 AM
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Member Group: Members Posts: 648 Joined: 9-May 05 From: Subotica Member No.: 384 |
There was statement that recently launched New Horizons is the fastest spacecraft to leave Earth. The velocity was 16.2 km/s relative to the Earth according to "Jonathan's Space Report".
QUOTE After the Star 48B burn, the payload had reached escape velocity not only with respect to the Earth but also relative to the Sun (The velocity was 16.2 km/s relative to the Earth and I estimate an asymptotic velocity of 12.3 km/s, corresponding to 42.6 km/s relative to the Sun... So: New Horizons is fastest to leave Earth at 16.2 km/s (relative to Earth). Voyager-1 is fastest to leave Solar System at 17.374 km/s (relative to Sun). Now that is OK. but what is this? Today's "Astronomy Picture of the Day" features launch of New Horizons and in text bellow image is one particularly interesting link to "Guinness world of records"... Guinness world of records; There "Mr. Guinness" claims that the fastest spacecrafts ever, were two Solar probes "Helios 1&2"...According to him those spacecrafts had speed of 252,800 km/h which is staggering 70.2 km/s...BUT RELATIVE TO WHAT????? Can somebody explain this? -------------------- The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful.
Jules H. Poincare My "Astrophotos" gallery on flickr... |
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May 8 2006, 04:06 PM
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
Well - consider a 1 gramme projectile at 10km/sec - that's 50,000 joules of energy
Consider it moving at 185 km/sec - that's 17112500 joules, or 342 times as much (i.e. 18.5 ^2 ) Doug |
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May 8 2006, 04:13 PM
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
That's true, but consider what are the odds of flying into a one-gram chunk (assuming you're not flying by a comet - in which case 200 km/s doesn't give you a big science op)? Present multi-layer protective blankets are IIRC designed to withstand micron-sized (or whatever) dust impacts. A 1-gram dust grain would punch through the shielding in both cases and would potentially be disastrous to the s/c. IMHO, it would be unfeasible to add shielding mass such that it would specifically protect the s/c against such large and statistically unlikely impacts.
Which reminds me of "whipple-shields" used on Stardust - how large impactors were they designed to hold? -------------------- |
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