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JPL Small-Body Mission-Design Tool Search: help ]



Welcome to the JPL Small-Body Mission-Design Tool [1]. This tool has been developed by the Solar System Dynamics Group (SSDG) at JPL to enable rapid mission design to any small body (asteroid or comet). In particular, this tool provides two services:

  • Pre-computed missions: an automatic process runs continuously on the SSDG servers and finds optimal mission opportunities to all asteroids and comets under specific design constraints. These pre-computed solutions are stored in the Small-Body Database and updated periodically.
  • Interactive mission design: once the target small body is identified, the system provides an interactive design interface to find mission opportunities to that particular body. The interface can be accessed anytime by typing the name, IAU number, SPK-ID, or designation of the object in the Search field on the top of this page.

The tool focuses on impulsive transfers, but it also provides a phase-free low-thrust ΔV estimate based on the algorithm in Ref. [2]. Each service is explained in more detail in the following. A tutorial is available for first-time users.

Pre-computed trajectories

The mission-design system runs continuously on JPL servers, and it automatically updates the database of pre-computed missions to all objects in the Small-Body Database as new bodies are added or existing orbits are updated. The first step when processing each small body consists in computing all impulsive mission options in a given range of launch dates, which spans 25 years into the future. The result is a transfer map or pork-chop plot with typically a 5-day resolution. A pork-chop plot is a time of flight (or arrival date) vs launch date map, with each point in the plot corresponding to a mission opportunity. The map is generated by advancing the launch date and time of flight using a fixed time step. For each launch date and time of flight, the resulting Lambert problem is solved using the algorithm in Ref. [3], whose solution defines the orbit transfer.

The second step in the process consists in sampling the most characteristic missions from the transfer map. A feature extraction algorithm has been developed to identify the most relevant missions and to capture as much information as possible with the minimum number of points possible. We consider a mission to be feasible if the departure C3 is less than 150 km2/s2.

The feature extraction algorithm runs a global search first, using a sliding window to sample the mission opportunities that minimize the departure C3 and the arrival V-infinity. Then, starting from each of the missions selected by the global search, the algorithm runs a local search under certain constraints on the launch C3. The local search seeks missions that minimize the other parameters, like the time of flight or the total ΔV (sum of the departure and arrival V-infinities). Only missions of less than 25 years are considered, and the database includes multi-revolution solutions when required. The set of pre-computed trajectories stored in the database are those trajectories that are extracted from the transfer map based on the feature extraction algorithm. The remaining trajectories in the transfer map are not stored.

Interactive mission design

The interactive web interface can be used to find mission options to a given small body, apart from the set of pre-computed trajectories stored in the database. The interface comprises three main elements:

  • Table of selected mission options: when the interface is loaded, the table contains only the set of pre-computed missions stored in the database. The table is interactive and the records can be sorted by any column. Switch to “Mass mode” to see the launch mass that can be inserted into orbit using different launch vehicles, considering both rendezvous and flyby missions. The table can be downloaded in CSV format at any time for archiving or further post-processing. The trajectories (user-selected, up to two at a time) can be plotted in 3D to visualize the mission.
  • Interactive pork-chop plot: it is generated on the fly using the API running on JPL servers. The different control panels can be used to fully customize the plot. The figure displays contours for one or two mission-design parameters, which can be specified by the user. The range of dates shown in the plot can be changed to cover different launch periods, even if they occurred in the past. Hovering the mouse over the figure gives information about each particular mission option, and clicking on a point will add the corresponding mission to the table of selected mission options.
  • Launch-vehicle selection tool: this interactive plot shows, for a given launch date, the maximum mass that can be delivered to the target by different launch vehicles. Use the mouse to find the preferred launch date, and then click on the plot to add that particular mission to the table. The times of flight might vary across the plot because maximum mass options were selected without considering specific constraints on the flight time (except for the upper limit used to compute the pork-chop plot). The performance curves have been derived from data from the NASA Launch Vehicle Performance Website.

API Service

Advanced users can access the API service directly to run their own simulations, or to connect it to their own applications. Specific instructions on how to interact with the API server can be found here.


  • Departure date: date of departure from Earth.
  • Arrival date: date of arrival at the small body.
  • MJD: modified Julian date, MJD = JD - 2400000.5.
  • V-infinity: hyperbolic excess velocity.
  • TOF: time of flight, time between arrival and departure.
  • C3: characteristic energy, equal to V-infinity squared.
  • Sun phase angle: angle between the incoming V-infinity vector and the Sun-target vector.
  • DLA: declination of the launch asymptote, angle between the outgoing V-infinity vector and Earth’s equatorial plane.
  • SEP angle: Sun-Earth-Probe angle (solar elongation), apparent angle on the sky between the Sun and the spacecraft.
  • Approach angle: angle between the incoming V-infinity vector and the heliocentric velocity vector of the target small body.
  • Range: distance to Earth.
  • SPK-ID: numeric object identifier in SPICE (go to the official NAIF site for details).

See the SSD glossary for more information.


[1] Roa, J., Chamberlin, A. B., Park, R. S., Petropoulos, A. E., Chodas, P. W., Landau, D. & Farnocchia, D. (2018). Automatic design of missions to small bodies. AIAA SciTech Forum, 2018 Space Flight Mechanics Meeting, January 8-12, Kissimmee, Florida, USA, doi: 10.2514/6.2018-0200.

[2] Edelbaum, T. N. (1965). Optimum power-limited orbit transfer in strong gravity fields. AIAA Journal, 3(5), 921-925, doi: 10.2514/3.3016.

[3] Arora, N., & Russell, R. P. (2013). A fast and robust multiple revolution Lambert algorithm using a cosine transformation. AAS/AIAA Astrodynamics Specialist Conference, August 11-15, Hilton Head, South Carolina, USA. Paper AAS 13-728.


The Mission Design System was designed and developed by Javier Roa (JPL/Caltech). Contributors: A. Chamberlin, R. Park, A. Petropoulos, P. Chodas, D. Landau, D. Farnocchia, and N. Arora.


Although every effort was made to ensure the accuracy and reliability of the data provided on this website, JPL and the Solar System Dynamics group will not be held responsible for any application of the information presented herein. The data is intended for research and preliminary design studies only.

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