Small Asteroid To Buzz Earth

ddelmonte writes in to tell us about a small near-earth object, discovered just 2 days ago, that is expected to pass within 64,000 km of our planet on March 2, 13:44 UT. NEO 2009 DD45 will be well inside the Moon's orbit and just under twice the altitude of geosynchronous satellites. According to Sky and Telescope, 2009 DD45's closest approach will be over the Pacific west of Tahiti, so observers in Australia, Japan, and perhaps Hawaii will have the best chance of spotting it with, say, an 8-in. telescope. Here's where you can generate an ephemeris of the object for your location. At closest approach NEO 2009 DD45 will be moving half a degree per minute and peaking around magnitude 10.5. It will be brighter than 13th magnitude for only a few hours.

Comments

Piggy ride!

[Chicken_Kickers]

Why can't we send a probe that will land on this asteroid and then piggy ride on it. That way we don't need more fuel to carry it round the solar system. If the asteroid doesn't go where we want, then have a relaunch mechanism for the probe to get off at the most suitable point in the asteroid's orbit.

Re:Piggy ride!

[amorsen]

Why can't we send a probe that will land on this asteroid and then piggy ride on it.

"Landing" would either actually be "crashing at a speed measured in km/s" or would require just as much fuel as going in the same orbit without the asteroid, and then what's the point...

Impossible in this timespan

[RabidMoose]

(IANARS) There's simply no way that any space agency could prepare and launch a probe with less than three days notice, and likely no good way to pre-build one without knowing what size/speed asteroid we might be lucky enough to launch at.

Re:Impossible in this timespan

[Puffy Director Pants]

Dude, if you can make a functional space craft that looks like an English Police box, I'll support your candidacy for head of Nasa.

Buzz vs. Non-buzz

[DynaSoar]

Three days notice. 20 to 50 meter diameter. Assume it's dense rock and a vertical impact trajectory into the ocean (avg. 1000 m depth).

Impact energy 116 kT to 1.8 MT. Very near the lowest energy potential impact of the known NEOs, actually. Not relevant here since the object quite clearly misses. But if and when one doesn't miss, someplace is going to catch a small to medium nuke sized blast, and there won't be time to do squat about it.

My money says we'll have the capability to defend ourselves against such an impact. The second time.

Re:Another perspective

[MartinSchou]

1 km/s is EXACTLY 3,600 km/h. Not roughly 30,000 km/h as you suggest.

So, I used a calc on the impact

[Ralph Spoilsport]

the calculator can be found here:
http://www.lpl.arizona.edu/impacteffects/

And the results are (assumed that you are 2000km from impact - if it hit it would be in the ocean...)

Your Inputs: Distance from Impact: 2000.00 km = 1242.00 miles
Projectile Diameter: 30.00 m = 98.40 ft = 0.02 miles
Projectile Density: 8000 kg/m3
Impact Velocity: 17.00 km/s = 10.56 miles/s
Impact Angle: 90 degrees
Target Density: 1000 kg/m3
Target Type: Liquid Water of depth 100.00
meters, over typical rock.

Energy: Energy before atmospheric entry: 1.63 x 1016 Joules = 3.90 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is 314.0 years

Atmospheric Entry: The projectile begins to breakup at an altitude of 14100 meters = 46100 ft
The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 10.8 km/s = 6.7 miles/s The impact energy is 6.58 x 1015 Joules = 1.57 MegaTons.
The broken projectile fragments strike the ground in an ellipse of dimension 0.151 km by 0.151 km

Major Global Changes: The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
What does this mean?

The crater opened in the water has a diameter of 1.4 km = 0.866 miles
For the crater formed in the seafloor: Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.
Transient Crater Diameter: 670 m = 2200 ft
Transient Crater Depth: 237 m = 777 ft
Final Crater Diameter: 837 m = 2750 ft
Final Crater Depth: 179 m = 586 ft

The crater formed is a simple crater
The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 82.8 m = 272 ft.
At this impact velocity ( Thermal Radiation: What does this mean?

At this impact velocity ( Seismic Effects: What does this mean?

The major seismic shaking will arrive at approximately 400 seconds.
Richter Scale Magnitude: 4.4
Mercalli Scale Intensity at a distance of 2000 km:
Nothing would be felt. However, seismic equipment may still detect the shaking.