Version: 1.2 (2017 March)
change log

The NHATS API provides a method of requesting data from the NHATS-related tables in the SBDB. These data will primarily support the CNEOS “Accessible NEAs” web-page. Please see the NHATS web-page for details about NHATS.

HTTP Request

GET https://ssd-api.jpl.nasa.gov/nhats.api

Example Queries

  • get summary data for available NHATS objects using various constraints:
    • https://ssd-api.jpl.nasa.gov/nhats.api (unconstrained)
    • https://ssd-api.jpl.nasa.gov/nhats.api?dv=6&dur=360&stay=8&launch=2015-2040&h=26&occ=7 (web-page “standard” constraints)
  • get details for the specified NHATS object:
    • https://ssd-api.jpl.nasa.gov/nhats.api?des=99942 (99942 Apophis, default constraints )
    • https://ssd-api.jpl.nasa.gov/nhats.api?des=2000%20SG344&dv=6&dur=360&stay=8&launch=2015-2040 (2000 SG344, constrained)

Query Parameters

This API supports two query modes. * S - obtain summary data spanning all available NHATS object * O - obtain details related to a specified NHATS object

Parameter Type Default Allowable Values Function Modes Description
dv int 12 4,5,6,7,8,
filter S,O Minimum total delta-V (km/s)
dur int 450 60,90,120,150,180,
filter S,O Minimum total duration (days)
stay int 8 8,16,24,32 filter S,O Minimum stay (days)
launch string 2015-2040 2015-2020,2020-2025,
filter S,O Launch window (year range)
h int none 16,17,18,19,20,
filter S Object’s maximum absolute magnitude, H (mag)
occ int none 0,1,2,3,4,
filter S Object’s maximum orbit codition code (OCC)
spk int none   selector O select data for the object matching this SPK-ID (e.g., 2000433 )
des string none   selector O select data for the object matching this designation (e.g., 2015 AB or 141P or 433)
plot boolean false 0,1,false,true option O include base-64 encoded plot image file content via output field plot_base64

The presence of an object selector query parameter (des or spk) distinguishes between the two modes (S and O). That is, if an object selector parameter is specified, an object detail query is executed (mode O). If no object selector parameter is specified, a summary query is executed (mode S).

Note that submitting a query parameter h along with des or spk results in an error because mode O (implied by des or spk) does not match mode S (implied by the presence of h).

Data Output

Please always check the JSON payload “signature” object for the “version”. If the version does not match the version in this document (at the top), there is no guarantee that the format has not changed.

Data are returned in JSON format. The specific structure used is dependent on the query mode.

Mode S

For summary queries (mode S), there may be no records matching the specified constraints. In such cases, the data count will be zero and the data array will be empty (or null). Normal results will contain a count of the number or records and an array of records with the following content. * fullname * constraints used (is this necessary? - convenient when defaults are selected) * NHATS object details * NHATS limits minima

The following is an example JSON-format data result matching three objects:

  "signature":{"version":"1.0","source":"NASA/JPL NHATS Data API"},
      "fullname":"1943 Anteros (1973 EC)",
      "min_dv":{"dv":"11.980", "dur":"354"},
      "des":"2000 SG344",
      "fullname":"(2000 SG344)",
      "min_dv":{"dv":"3.550", "dur":"370"},
      "des": "2006 RH120",
      "fullname":"(2006 RH120)",
      "min_dv":{"dv":"3.972", "dur":"450"},
      "obs_flag":" ",

Mode O

For object detail queries (mode O), it is possible to get no matching results for a valid NHATS object if the constraints are too limiting. In such cases, the JSON payload will contain an error keyword with appropriate message.

{ "error" : "no matching results for specified object and constraints" }

Similarly, in cases where the specified object is not an NHATS object, the JSON payload will contain a message similar to the following.

{ "error" : "specified NHATS object not found"" }

Normal results will contain the following JSON structure. * fullname * NNATS object details * constraints used * NHATS trajectory details (two trajectory records: min_dv and min_dur) * plot file image contents base64-encoded (if requested)

The JSON-format result will look something like this:

  "signature":{"version":"1.0","source":"NASA/JPL NHATS Data API"},
  "fullname":"(2000 SG344)",
  "min_dv":{"dv":"3.550", "dur":"370"},
  "plot_base64":"iVBORw0KGgoAAAAN ... AASUVORK5CYII=",

HTTP Response Codes

All errors are returned via appropriate HTTP response codes. Note that it is possible to submit query parameters resulting in no matching data. In such cases, a non-error code of 200 is returned so the user is responsible for checking the payload if they wish to detect a null-result.

HTTP Code Description Typical Usage
200 OK normal successful result: data returned (may be empty) or an error message (for example, if the des/spk was not found)
400 Bad Request the request contained invalid keywords and/or content or used a request-method other than GET or POST (details returned in the JSON payload)
405 Method Not Allowed the request used a method other than GET or POST
500 Internal Server Error the database is not available at the time of the request

Background Information

The primary NHATS data table as rendered in the current NEO web-site contains a number of parameters. These various parameters require database queries of several different tables in the SBDB. In addition, the data is rendered initially with filter parameters applied.

The main NHATS data table currently allows for filtering by placing user-specified constraints on the following parameters:

  • total delta-V (e.g., <= 6 km/s)
  • total duration (e.g., <= 360 days)
  • stay (e.g., >= 8 days)
  • launch window (years: e.g., 2015-2040)
  • H magnitude (e.g., <= 26)
  • OCC (e.g., <= 7)

Primary NHATS Web-Page Data Table Columns

table.item web-page table label
Object Designation
nhats_object.orbit_id Orbit ID
nhats_object.H H (mag)
Estimated Diameter (m)
nhats_object.occ OCC
Min. delta-V [delta-V, dur.] (km/s), (d)
Min. Duration [delta-V, dur.] (km/s), (d)
nhats_object.n_via_traj Viable Trajectories
Next Optical Opportunity (yyyy-mm [Vp])
Next Arecibo Radar Opportunity (yyyy-mm [SNR])
Next Goldstone Radar Opportunity (yyyy-mm [SNR])

Detail (object-specific) NHATS Web-Page Data Table Items

table.item web-page table label
nhats_traj.dv_total Total Mission delta-V (km/s)
nhats_traj.dur_total Total Mission Duration (d)
nhats_traj.dur_out Outbound Flight Time (d)
nhats_traj.dur_at Stay Time (d)
nhats_traj.dur_ret Inbound Flight Time (d)
nhats_traj.launch Launch date (YYYY-MM-DD)
nhats_traj.c3 C3 (km2/s2)
nhats_traj.v_dep_earth Departure Vinfinity (km/s)
nhats_traj.dv_dep_park Earth Departure dV (km/s)
nhats_traj.vrel_arr_neo dV to Arrive at NEA (km/s)
nhats_traj.vrel_dep_neo dV to Depart NEA (km/s)
nhats_traj.vrel_arr_earth Earth return dV (km/s)
nhats_traj.v_arr_earth Entry Speed (km/s)
nhats_traj.dec_dep Depature Declination (deg)
nhats_traj.dec_arr Return Declination (deg)
nhats_traj.tid NHATS Trajectory Solution ID

Change Log

Version 1.2 (2017 March)

  • Obsolete plot URL output field plot has been removed. Use plot_base64 instead.

Version 1.1 (2017 February)

  • Plot data file contents (base64-encoded) are now optionally available in field plot_base64.
  • Prior plot URL output field plot is obsolete and will been removed soon (due to the URL source being removed).
  • removed extraneous fields from min_dv_traj and min_dur_traj

Version 1.0 (2016 August)

  • Initial release