Conversion from/to SMA

spacekernel.state.orp_from_sma(sma: double | ndarray[double], GM: double = Earth.GM) → double | ndarray[double]

Compute orbital period(s) from semimajor axis (or axes).

Parameters:

smafloat or ndarray of shape (N,)

Semimajor axis (or array of semimajor axes) [meters].

GMfloat, optional

Standard gravitational parameter [m^3/s^2]. Default is Earth’s value.

Returns:

orpfloat or ndarray of shape (N,)

Orbital period(s) [seconds].

Notes

• Accepts single values or arrays of values.

• Formula:

  ORP = 2π * a * sqrt(a / GM)

spacekernel.state.sma_from_orp(orp: double | ndarray[double], GM: double = Earth.GM) → double | ndarray[double]

Compute semimajor axis (or axes) from orbital period(s).

Parameters:

orpfloat or ndarray of shape (N,)

Orbital period(s) [seconds].

GMfloat, optional

Standard gravitational parameter [m^3/s^2]. Default is Earth’s value.

Returns:

smafloat or ndarray of shape (N,)

Semimajor axis (or axes) [meters].

Notes

• Accepts single values or arrays of values.

• Formula (inversion of period equation):

  SMA = [GM * (ORP / 2π)^2]^{1/3}

spacekernel.state.mnm_from_sma(sma: double | ndarray[double], GM: double = Earth.GM) → double | ndarray[double]

Compute mean motion(s) from semimajor axis (or axes).

Parameters:

smafloat or ndarray of shape (N,)

Semimajor axis (or array of semimajor axes) [meters].

GMfloat, optional

Standard gravitational parameter [m^3/s^2]. Default is Earth’s value.

Returns:

mnmfloat or ndarray of shape (N,)

Mean motion(s) [radians/second].

Notes

• Accepts single values or arrays.

• Formula:

  MNM = sqrt(GM / a) / a

spacekernel.state.sma_from_mnm(mnm: double | ndarray[double], GM: double = Earth.GM) → double | ndarray[double]

Compute semimajor axis (or axes) from mean motion(s).

Parameters:

mnmfloat or ndarray of shape (N,)

Mean motion(s) [radians/second].

GMfloat, optional

Standard gravitational parameter [m^3/s^2]. Default is Earth’s value.

Returns:

smafloat or ndarray of shape (N,)

Semimajor axis (or axes) [meters].

Notes

• Accepts single values or arrays.

• Formula (inversion of mean motion equation):

  a = [GM / mnm^2]^{1/3}