BUG: collection irtf_mearth returns no results

Not sure if this is astroquery or upstream problem, I open this issue to keep track of it.

```
In [7]: Irsa.query_sia(collection='irtf_mearth')
Out[7]:

s_ra s_dec facility_name instrument_name dataproduct_subtype calib_level dataproduct_type ... s_fov em_xel pol_states pol_xel cloud_access o_ucd upload_row_id
deg deg ... deg
float64 float64 object object object int16 object ... float64 int64 object int64 object object int64
------- ------- ------------- --------------- ------------------- ----------- ---------------- ... ------- ------ ---------- ------- ------------ ------ -------------
```

Start with the Irsa.query_sia(collection='irtf_mearth') entry point and reproduce the empty table response. Compare the result with the upstream SIA service to determine whether the problem is in astroquery or upstream; done means the source is identified and the issue is fixed or documented with supporting evidence.

Written by the indexing model from the issue text.