gogglefu is weak....

[Sarlon]

so I have this assignment in my "Life in the Universe" class and I've found the 4 asteroids I need, but I can't find their mass of closest distance they got to earth....

Look for "close" approaches of Near Earth Objects that have occurred since January 1st of this year. However, list only those that came within 1 Lunar Distance (1 LD) of the Earth. [1.0 LD is about 3.84x10^5km or 0.00257 AU (the average distance between the Earth and the Moon).] Thus, these are objects that actually passed between the earth and the moon although the earth was never in any real danger of being struck by them.

the ones I've found are...
AQ43
BP513
BE511
CH13
DD1

I have thier size, I can't find their mass, or distance at closest approach.

can anyone help?

[Kittish]

Any calculation of mass is going to be largely guesswork, since we don't know the exact composition of each body. You could fudge it by assuming that they're all chondritic, and use 3g/cubic centimeter as a reasonable density.

2015 BP513:

On 18 January 2015 13:36 UT the asteroid passed 0.00082 AU (123,000 km; 76,000 mi) from the Moon and at 17:09 UT passed 0.0016 AU (240,000 km; 150,000 mi) from Earth.

Wikipedia, abstracted from JPL data.

2015 BE511: 2015-Jan-20 07:54 < 00:01 Moon Nominal Distance 0.00300927128419597 Min 0.00300604863423213 Max 0.00301249735458922
2015-Jan-20 13:06 < 00:01 Earth Nominal Distance 0.0010794218908105 Min 0.00107619640032807 Max 0.00108264715953885

2015 CH13: 2015-Feb-11 06:17 < 00:01 Earth Nominal Distance 0.00188843661455945 Min 0.00187974911468695 Max0.0018971331472369 15.3021695588288
2015-Feb-11 08:05 < 00:01 Moon Nominal Distance 0.00434437676945017 Min 0.00433604346764673 Max 0.00435271543691226
This is a busy guy, been making near approaches that we've recorded since 1947.

2015 AQ43: 2015-Jan-14 13:11 < 00:01 Moon Nominal Distance 0.00367302836134512 Min 0.00367150734551648 Max 0.00367455015448955
2015-Jan-14 13:20 < 00:01 Earth Nominal Distance 0.00105317733002064 Min 0.00105164918197924 Max 0.00105470631768279

2015 DD1: 2015-Feb-16 21:48 < 00:01 Moon Nominal Distance 0.00178509188356542 Min 0.00178453324155475 Max 0.00178565060431804
2015-Feb-17 07:38 < 00:01 Earth Nominal Distance 0.000262402423047253 Min 0.000262278284303078 Max 0.000262526528997209

So all of this info is from the JPL Small-Body Database. The big long numbers are AUs, values given are for each object's closest approach to moon and earth this year. To search that data base, your format has to follow how I have them written, year then object designation, otherwise you come up empty. Also, their search function is case sensitive.

And for some reason now I can't get the Hot Fudge Tuesday lecture out of my head. (Larry Niven, Jerry Pournelle- Lucifer's Hammer)