Isotopic ratio

Atmosphere

Mars

Earth

Mars/Earth

D/H (in H₂O)

9.3‰ ± 1.7‰

1.56‰

~6

¹²C/¹³C

85.1 ± 0.3

89.9

0.95

¹⁴N/¹⁵N

173 ± 9

272

0.64

¹⁶O/¹⁸O

476 ± 4.0

499

0.95

³⁶Ar/³⁸Ar

4.2‰ ± 0.1‰

5.305

0.79

⁴⁰Ar/³⁶Ar

1900 ± 300

298.56 ± 0.31

~6

C/⁸⁴Kr

(4.4 - 6) × 10⁶

4 × 10⁷

~0.1

¹²⁹Xe/¹³²Xe

2.5221 ± 0.0063

0.97

~2.5