This area will cover relevant news of the threat to the planet from Near Earth Objects (NEOs) including concepts and designs for mitigation. All opinions are those of the author.

27 February 2006

Confirmation of Threat: 2004 VD17 Gets a Torino Rating of 2 (1 in 1,850 chance of hitting the Earth)

Object 2004 VD17 was given a Torino scale rating of 2, apparently only the second time in risk monitoring history this has happened. Thus currently only two objects have a Torino scale rating above 0: the well known 99942 Apophis (2004 MN4) and now 2004 VD17. However, whereas Apophis has close approaches within the next few decades, 2004 VD17 projections reveal close approaches in 2096, 2102, and 2104. 2004 VD17 has a 1 in 1,850 chance of hitting the Earth whereas Apophis has a 1 in 5,880 chance of Earth impact.

Here are some estimated parameters for 2004 VD17 from the most recent observations by JPL on Feb. 23, 2006:

Diameter: 0.580 km
Mass: 2.7e+11 kg
Torino Scale (maximum): 2
Palermo Scale (maximum): -0.40
Palermo Scale (cumulative): -0.40
Impact Probability (cumulative): 5.4e-04
Number of Potential Impacts: 4

Torino Scale 2 Definition: "A discovery, which may become routine with expanded searches, of an object making a somewhat close but not highly unusual pass near the Earth. While meriting attention by astronomers, there is no cause for public attention or public concern as an actual collision is very unlikely. New telescopic observations very likely will lead to re-assignment to Level 0."

- More detail from

Notes: 2004 VD17 was discovered by LINEAR on 7 Nov. 2004 and was announced the next day. It was posted with impact solutions at JPL and NEODyS on 9 Nov. when further observations became available. JPL elevated 2004 VD17 to Torino Scale 1 (a routine alert that an object "merits special monitoring") on 22 Nov., and NEODyS put it at TS-1 on the 23rd.

2004 VD17 had been noted to go out of view on 5 Feb. 2005 and wasn't observed after 28 Jan. until David Tholen's team picked it up from Mauna Kea on March 4th, which was published 13 days later.

On 15 Nov. 2005 it was reported that Tholen's team had recovered 2004 VD17 on the 4th, 11th, and 13th of that month using the University of Hawaii 2.2m telescope on Mauna Kea. This more than tripled the object's observation arc, from 117 to 371 days.

2004 VD17 brightened into view in early Feb. 2006 and was picked up with the Spacewatch 1.8m telescope on 6 Feb. It remains in view until around June 22nd, then comes back again in late July for the rest of the year. NEODyS notes "Very accurate observations necessary in March."

On 6 Feb. 2006, for only the second time in risk monitoring history, 2004 VD17 was raised to a Torino Scale rating of 2 (for "a somewhat close but not highly unusual pass near the Earth ... an actual collision is very unlikely"). JPL raised it to TS-2 after the next observation became available on Feb. 23rd.

Link Wikipedia Entry on 2004 WD17

Link: hohmanntransfer website

Link: 2004 VD17 Earth Impact Risk Summary from JPL

Link: Recently Observed Objects Risk Scale from JPL

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