Asteroid First

JPL just released an interesting report :


Study to Determine the Feasibility of Extending the Search for
Near-Earth Objects to Smaller Limiting Diameters

He

http://neo.jpl.nasa.gov/neo/neoreport030825.pdf

Al Jackson wrote:
JPL just released an interesting report :


Study to Determine the Feasibility of Extending the Search for
Near-Earth Objects to Smaller Limiting Diameters

He

http://neo.jpl.nasa.gov/neo/neoreport030825.pdf

I'm excited about the proposal for a heliocentric observatory at .7 AU.
At http://neo.jpl.nasa.gov/risk/
there are a few asteroids with close to one A.U. aphelions and periods
less than a year. I would think such asteroids would be very hard to see
as they spend most of their time in the day sky. An inner system
observatory is needed to inventory these asteroids. They estimate $65
million for this? That seems inexpensive.

According to this paper Tunguska sized impacts are thought to occur
every 1 or 2 millenia. This seems less frequent than earlier guestimates
I seem to recall.

Hop
http://clowder.net/hop/index.html

In article , Hop David wrote:

I'm excited about the proposal for a heliocentric observatory at .7 AU.
At http://neo.jpl.nasa.gov/risk/
there are a few asteroids with close to one A.U. aphelions and periods
less than a year. I would think such asteroids would be very hard to see
as they spend most of their time in the day sky. An inner system
observatory is needed to inventory these asteroids. They estimate $65
million for this? That seems inexpensive.

For an orbiting deep-space probe? Very, to my mind. I suppose the
"science package" is fairly well-understood stuff (a scanning platform,
an optical telescope, a good quality CCD), and the thermal/power
benefits of it being in constant sunlight (it makes the engineering
easier, I suppose) help, but I still can't see it being cheap.

That said, I haven't read the proposal yet - paper's still downlaoding
(damn dialup...). Have a look through it tonight, but on its own the
idea seems feasible. Is it likely funding could be found for it?

According to this paper Tunguska sized impacts are thought to occur
every 1 or 2 millenia. This seems less frequent than earlier guestimates
I seem to recall.

I thought the figure was about 1/10 of that, but I wouldn't place bets
on my memory ;-)

--
-Andrew Gray

In article , Hop David wrote:

I'm excited about the proposal for a heliocentric observatory at .7 AU.
At http://neo.jpl.nasa.gov/risk/
there are a few asteroids with close to one A.U. aphelions and periods
less than a year. I would think such asteroids would be very hard to see
as they spend most of their time in the day sky. An inner system
observatory is needed to inventory these asteroids. They estimate $65
million for this? That seems inexpensive.

I've been flicking through this section (that number intrigued me) and I
see the problem - that figure's quoted on pp. 99, but *only* covers
operating costs - it doesn't cover launch or satellite costs. The *next*
page gives a cost of $69m for the Delta II, and on the page after that
it gives a total cost, craft & instrument & operations & launch costs
with a reserve added, and the 0.7AU job comes out between $300m and
$375m, depending on the instrument, for a ten-year operating mission.

That is a little more than $65, but dare I say it seems a little more
believable. :-)

--
-Andrew Gray

Andrew Gray wrote:
In article , Hop David wrote:

According to this paper Tunguska sized impacts are thought to occur
every 1 or 2 millenia. This seems less frequent than earlier guestimates
I seem to recall.

I thought the figure was about 1/10 of that, but I wouldn't place bets
on my memory ;-)


About 1/century is probably about right. But note that a lot of Eart's
surface is covered by oceans.

--
Sander

+++ Out of cheese error +++

In article , Andrew Gray wrote:

with a reserve added, and the 0.7AU job comes out between $300m and
$375m, depending on the instrument, for a ten-year operating mission.

That is a little more than $65, but dare I say it seems a little more
believable. :-)

Um, that was $65 *million*... a little closer to the relevant ballpark
;-)

--
-Andrew Gray

"Hop David" wrote:
I'm excited about the proposal for a heliocentric observatory at .7 AU.

That would be very cool.


At http://neo.jpl.nasa.gov/risk/
there are a few asteroids with close to one A.U. aphelions and periods
less than a year. I would think such asteroids would be very hard to see
as they spend most of their time in the day sky. An inner system
observatory is needed to inventory these asteroids. They estimate $65
million for this? That seems inexpensive.

Well, it is inexpensive, but that's not unexpected for this
type of mission. You've got the basic costs of being a
deep space probe / interplanetary probe and of being a
moderately sized space telescope, and you've got some
basic instrument costs, but beyond that you don't have a
whole lot to run up the cost. It doesn't have to land on
anything or orbit anything (except the Sun) or rendezvous
with anything. It doesn't have to gather all that much
data on asteroids, just find them, it doesn't need all
the multispectral googaws on most science spacecraft, nor
the other stuff like spectrometers, ion instrumentation,
magnetic this and that, etc. $65 million seems about
right.

Martha H Adams wrote:
I think looking at space better and seeing it better, is a good idea
but the wrong priority. For one thing, if some automated astronomical
observatory actually spots a Terra Killer, what resources do we have
to deal with it? About the only resource I'm hearing of, is the
faith-based intervention: get down on your knees and pray. Such

There are some approaches that seem plausible to deflect it, even without
existing space-based assets. (the stuff we have up is pretty much irrelevant)

At the moment, 10Km 20 years out is probably somewhere close to the limits.
Using nuclear bombs to flash-boil the surface and push it out of the way.

This is around dinosaur-killer class mass.

Even with this sort of impact, life remains on earth, and it's quite likely
that some of humanity would survive. The continents change shape, lots of
volcanism, global weather effects lasting centuries, permenant biosphere
changes.

Much bigger than this, and you pretty much have to divert it for life on earth
to survive at all.

100Km impactors, which are fortunately vanishingly rare nowadays would need to
be spotted at least a century or so in advance, with near current tech.
Then again, it's probably not reasonable to work out timescales for
something that will take a century to complete, as technology advances
so fast.



--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
If you've been pounding nails with your forehead for years, it may feel strange
the first time somebody hands you a hammer.
But that doesn't mean that you should strap the hammer to a headband just to
give your skull that old familiar jolt. -- Wayne Throop, during the `TCL Wars'

In article ,
Hop David wrote:
...there are a few asteroids with close to one A.U. aphelions and periods
less than a year. I would think such asteroids would be very hard to see
as they spend most of their time in the day sky. An inner system
observatory is needed to inventory these asteroids.

Nonsense. It suffices to do it from Earth orbit, where a good sunshade
will let you observe much closer to the Sun than ground observatories can.
But that's not sexy enough for JPL...

Not coincidentally :-), I happen to be involved in such a project. And
using a MOST derivative, it would be an order of magnitude cheaper than
JPL's deep-space version.

The inner-system observatory is better, yes, but it's not an order of
magnitude better.

According to this paper Tunguska sized impacts are thought to occur
every 1 or 2 millenia. This seems less frequent than earlier guestimates
I seem to recall.

There has been some re-evaluation of the numbers lately. While people are
still arguing about details, it does appear that substantial rocks are
somewhat less common than previously thought.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

Hop David wrote:
...there are a few asteroids with close to one A.U. aphelions and
periods less than a year. I would think such asteroids would be
very hard to see as they spend most of their time in the day sky.
An inner system observatory is needed to inventory these asteroids.

Henry Spencer wrote:
Nonsense. It suffices to do it from Earth orbit, where a good
sunshade will let you observe much closer to the Sun than ground
observatories can.

Nonsense. It suffices to do it from Earth. So long as the asteroid
is more than about 20 degrees from the sun, it can be seen as easily
as any other asteroid. And if it's never any further from the sun than
that, then it's no threat to earth -- or to Mercury or Venus either.
--
Keith F. Lynch - - http://keithlynch.net/
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