Comet put on list of potential Earth impactors

New Scientist ^ | 1 June 2005 | David L Chandler

[SunkenCiv]

On 26 May, JPL's unique orbital calculation software determined that Comet Catalina was on what could possibly be a collision course with Earth, though the odds of such an impact were small: just 1 chance in 300,000 of a strike on June 11, 2085. Based on the 980-metre size estimate, that would produce a 6-gigaton impact - equivalent to 6 billion tonnes of TNT.

Astronomers expected the addition of further observations to the calculations to rule out any possibility of a collision, as happens with most newly-seen objects.

But that did not quite happen. The comet's predicted pathway actually drew even closer to making a perfect bull’s-eye with the Earth - its predicted path passes within 1000 kilometres of the where the centre of our 12,700-km-diameter planet will be around that time.

However, uncertainty in the exact timing of the comet’s pass through the line of Earth’s orbit dropped the odds of an impact to about 1 in 120 million. That is very low, but the observations so far cannot categorically rule a collision out.

[reg45]

Maybe it will hit Mecca!

[reg45]

Crap, June 11, 2085 I've got tickets to a Rangers game that day, just my luck.

That's a long time to wait for a winning season!

;-)

[RightWhale]

The new director favors the BDB. The old director did not know what a BDB is. The BDB doesn't have to be based on the Space Shuttle, but at least some of the hardware is still in manufacture, so that will avoid some tooling and training costs.

[SunkenCiv]

BDB... "Big D***** Booster"... ?

http://www.cpia.jhu.edu/Acronyms/

Bis(difluoramino)butane

[RightWhale]

Big dumb booster.

Wagons, ho!

[SunkenCiv]

I think problems will arise if an old design is revived (say, the F-1, the production for which could be restarted), partly because of the mindless pursuit of the new, but also, and mainly, because of the political struggle over where the components would be built. We already know where the Dims stand -- against human spaceflight, particularly a return to the Moon. Von Braun's model was a step by step approach: learn how to do each job needed to get to (ultimately) Mars. First, get to space and reenter; then orbit; then spacewalking; then rendezvous; then docking; then a trip around the Moon and back; then test the landing vehicle and safe return; then land, plant the flag, grab some rocks, and safe return; then repeat the process a number of times.

All of that will also have to be redone, probably in simulators using CGI.

Von Braun's human mission to Mars would have involved twelve Saturn V launches to assemble in LEO and send it on its way. Of course, it would have merely begun the process of getting there. The first mission might have been crewed, but would have been an orbit-and-return. Then again, perhaps Apollo missions (including 18 through 21, which were scrapped) would have been judged to have provided a sufficient base of experience for an immediate landing mission.

Saturn 5 Blueprints Safely in Storage
space.com | 13 March 2000 | By Michael Paine
Posted on 01/08/2004 2:20:33 PM PST by Dead Dog
http://www.freerepublic.com/focus/f-news/1054183/posts

[RightWhale]

NASA has the concept of an earth-Mars shuttle system, which might consist of more than one shuttle vehicle continually going back and forth, as well as an earth-moon shuttle system. The idea of a transportation infrastructure would be intended for longterm discovery and development rather than a few one-off missions. That is, there would be regular transportation to and from the moon and Mars from now on. While it would cost something to set up, it should be cost-effective in the long run. Something similar would be done with respect to the Asteroid Belt by the private sector if asteroid mining is ever allowed.

[SunkenCiv]

that page is still gone, and the cache I linked appears to have expired. There is another cached version (which I'm about to post).

Google

[SunkenCiv]

Three objects with Torino 1 on this list:

http://neo.jpl.nasa.gov/risk/

[SunkenCiv]

Asteroid mining might be better done with NEOs, rather than all the way out to the asteroid belt.

[SunkenCiv]

Comet Catalina (P/2005 JQ5) Impact Risk (cached version)

+ View the NASA Portal

Back to main Impact Risk Page.

Comet Catalina (P/2005 JQ5)
Earth Impact Risk Summary

Torino Scale (maximum)	0
Palermo Scale (maximum)	-4.65
Palermo Scale (cumulative)	-4.65
Impact Probability (cumulative)	8.1e-09
Number of Potential Impacts	1

Vimpact	19.95 km/s
Vinfinity	16.55 km/s
H	17.7
Diameter	0.980 km
Mass	1.3e+12 kg
Energy	6.0e+04 MT
all above are mean values weighted by impact probability

Analysis based on
371 observations spanning 23.870 days
(2005-May-06.27858 to 2005-May-30.14837)

Orbit diagram and elements available here.

These results were computed on May 31, 2005

Comet Catalina (P/2005 JQ5) Earth Impact Table
Date	Distance	Width	Sigma Impact	Sigma LOV	Stretch LOV	Impact Probability	Impact Energy	Palermo Scale	Torino Scale
YYYY-MM-DD.DD	(rEarth)	(rEarth)			(rEarth)		(MT)
2085-06-11.90	0.06	4.52e-02	0.000	-3.92000	4.54e+04	8.1e-09	6.02e+04	-4.65	0

Summary Table Description

The Summary Table includes basic information about the hazard for this object. The maximum Torino and Palermo Scale values are listed, as well as the number of tabulated potential impacts and their corresponding cumulative Palermo Scale value and cumulative impact probability. The observation set used for the analysis is also listed. Certain parameter values depend upon the specific impact event in question, but they change little among the various table entries. For this reason we tabulate only mean values for these parameters:

• V_impact - Velocity at atmospheric entry.
• V_infinity - Relative velocity at atmospheric entry neglecting the acceleration caused by the Earth's gravity field, often called the hyperbolic excess velocity. (V_infinity² = V_impact² - V_escape², where V_escape = ~11.2 km/s is the Earth escape velocity.)
• H - Absolute Magnitude, a measure of the intrinsic brightness of the object.
• Diameter - This is an estimate, based on the absolute magnitude, and assuming a uniform spherical body with visual albedo p_V = 0.154. Since the albedo is rarely well determined the diameter estimate should be considered quite rough, but in most cases will be accurate to within a factor of two.
• Mass - This estimate assumes a uniform spherical body with the computed diameter and a mass density of 2.6 g/cm³. The mass estimate is somewhat more rough than the diameter estimate, but generally will be accurate to within a factor of three.
• Energy - The kinetic energy at impact: 0.5 * Mass * V_impact². Measured in Megatons of TNT.

Impact Table Legend

See our Introduction for a more extensive explanation of these terms.

Date

The calendar date (UTC) of the potential impact.

Distance

The minimum distance on the target plane (scaled b-plane) from the LOV to the geocenter, measured in Earth radii. For these purposes the radius of the Earth, 6420 km, includes some allowance for the thickness of the atmosphere.

Width

The one-sigma semi-width of the LOV uncertainty region, measured in Earth radii.

Sigma Impact

The lateral distance in sigmas from the LOV to the Earth's atmosphere. Zero indicates that the LOV intersects the Earth. It is computed from (Distance - 1)/Width.

Sigma LOV

The coordinate along the Line Of Variations (LOV). This value is a measure of how well the impacting orbit fits the available observations. Zero indicates the best-fitting, central (nominal) orbit and the further from zero, the less likely the event: Roughly 99% of all the uncertainty region lies between -3 and +3. Sentry explores out to Sigma LOV = +/-5.

Stretch LOV

The stretching is the semimajor axis of the local linear uncertainty region. It describes how fast one moves across the target plane as Sigma LOV changes, and is measured in Earth radii per sigma. The local probability density varies inversely with the stretching, and thus larger stretching values will generally lead to lower impact probabilities.

Impact Probability

The probability that the tabulated impact will occur. The probability computation is complex and depends on a number of assumptions that are difficult to verify. For these reasons the stated probability can easily be inaccurate by a factor of a few, and occasionally by a factor of ten or more.

Impact Energy

The kinetic energy at impact, based upon the computed absolute magnitude and impact velocity for the particular case, and computed in accordance with the guidelines stated for the Palermo Technical Scale. Uncertainty in this value is dominated by mass uncertainty and the stated value will generally be good to within a factor of three.

Palermo Scale

The hazard rating according to the Palermo Technical Impact Hazard Scale, based on the tabulated impact date, impact probability and impact energy.

Torino Scale

The hazard rating according to the Torino Impact Hazard Scale, based on the tabulated impact probability and impact energy.

Site Manager: Don Yeomans Webmaster: Ron Baalke Last Updated:

[RightWhale]

Not much to choose from with NEOs. Asteroid Belt has all three kinds.

[SunkenCiv]

Ah ha. Here's the blankity blank URL. The NEO JPL NASA people added "P". I guess that makes the ice melt faster or somethin'.

http://neo.jpl.nasa.gov/risk/p2005jq5.html

[SunkenCiv]

http://www.house.gov/science/press/109/109-78.htm

NOAA, NASA BILLS SAIL THROUGH COMMITTEE

WASHINGTON, D.C., May 17, 2005

H.R. 1022, also introduced by Rep. Rohrabacher, would establish a program within NASA to detect, track, catalogue, and characterize the physical properties of near-Earth asteroids and comets equal to or greater than 100 meters in diameter in order to assess the threat of Earth being struck by such near-Earth objects.  The bill would authorize appropriations for the program of $20 million for each of fiscal years 2006 through 2007.

Rep. Rohrabacher said, "The potential catastrophe of an asteroid hitting Earth should no longer be ignored. We need to know what is out there. Accounts of asteroids passing close to Earth with almost no prior warning should be enough to get our attention. The first step is to assess the threat. Given the vast number of asteroids and comets that inhabit the Earth's neighborhood, greater efforts for tracking and monitoring these objects are critical. This bill would direct NASA to expand their current program to track and detect potential threats and would provide a funding authorization. Any threat that would wreak havoc on or world should be studied and prevented if possible. We have the technology, we need the direction – this bill provides that."

[RightWhale]

The threat has been assessed for years. When will hardware be placed in deep space so something may actually be done?

[SunkenCiv]

Too easy to weaponize.

That URL I posted in message 33 is gone now. This is annoying.

[RightWhale]

They are going to have 1000s of tungsten telephone poles up there anyway. No need to worry.

[SunkenCiv]

NEO Earth Close Approaches
http://neo.jpl.nasa.gov/ca/

NEOs Removed from Impact Risk Tables
http://neo.jpl.nasa.gov/risk/removed.html

[SunkenCiv]

everyone could use a laugh, right?

Huge asteroid to fly past Earth (Toutatis hoax - how and why)
space.com | 04/09/29
Posted on 09/29/2004 5:00:09 AM PDT by Truth666
http://www.freerepublic.com/focus/f-chat/1230167/posts

[RightWhale]

WhenI was designing my asteroid mining business proposal I deliberately ignored earth orbit crossing bodies and assumed all mining would be in the main Asteroid Belt. Two reasons:

1. A lot more material to choose from, and

2. I needed to compute far fewer orbits.