How ‘Porkchop Plots’ Determine Earth-to-Mars Trajectories | #NASA

If you listened to Episode 1 of NASA’s newest podcast Rocket Ranch you might have heard the term ‘porkchop plot’ used a few times. This whitepaper co-authored by JPL Mars Advanced Studies and Program Architecture Office Manager Charles W. Whetsel describes what porkchop plots are and how they assist “ballistic trajectories between two [celestial] bodies.”

Plotting interplanetary trajectory parameters such as C3 and V∞ in launch-date/arrival-date space and tracing isometric lines are a valuable mission design tool that are used in optimizing the trajectories for most interplanetary missions. The most important energy parameters (C3 and V∞) typically create bi-lobed characteristic shapes which have earned these plots the colloquial nickname of “porkchop” plots. Porkchop plots aide early mission designers in selecting launch dates, in calculating launch energies and ΔV budgets, and visually optimizing trajectories. Launch periods are designed by applying constraints on some parameters (e.g. launch declination, arrival dates, launch period duration, entry speed, sun angles) while simultaneously minimizing others (e.g. launch energy, Mars orbit insertion (MOI) ΔV).1,2,3

Each opportunity (~26 months for Earth to Mars) a new porkchop plot is created with similar characteristics, but with different minima (on either side of the central ridge), minima locations, ridge width, and lobe shapes. In this paper we investigate how the orbital characteristics of Earth and Mars affect the nature of the porkchop plots and how they compare to ideal (circular, coplanar) and optimized (allowing launch, arrival, and transfer time to be free parameters) porkchop plots. We also explore what defines a “good” opportunity for Mars missions and to what extent certain characteristics repeat with Mars cycles (approximately 15 years or 7 opportunities) and super-cycles.

Lambert’s Theorem can be used to calculate the orbital parameters of the trajectory between any two points for a given time of flight (TOF). This means that for any launch date at Earth (which specifies location 1) and arrival date at Mars (which specifies location 2 and TOF), there exists a conic trajectory connecting the two. Plotting contours of the relevant parameters of the connecting trajectories against combinations of launch date and arrival date create a two-lobed chart known as a porkchop plot. While traditional porkchop plots often portray the specific departure energy and hyperbolic excess arrival energy individually (C3 and V∞ respectively), for the purposes of this investigation, the authors chose to focus on a combination of these parameters, termed the “total transfer ΔV”. Figure 1 shows total transfer ΔV (defined in Equation 1, below) for the 2018 Earth-to-Mars opportunity.

Read more here.

Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here:

Join Adafruit on Mastodon

Adafruit is on Mastodon, join in!

Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Join over 36,000+ makers on Adafruit’s Discord channels and be part of the community!

CircuitPython – The easiest way to program microcontrollers –

Maker Business — “Packaging” chips in the US

Wearables — Enclosures help fight body humidity in costumes

Electronics — Transformers: More than meets the eye!

Python for Microcontrollers — Python on Microcontrollers Newsletter: Silicon Labs introduces CircuitPython support, and more! #CircuitPython #Python #micropython @ThePSF @Raspberry_Pi

Adafruit IoT Monthly — Guardian Robot, Weather-wise Umbrella Stand, and more!

Microsoft MakeCode — MakeCode Thank You!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — #NewProds 7/19/23 Feat. Adafruit Matrix Portal S3 CircuitPython Powered Internet Display!

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at !

No Comments

No comments yet.

Sorry, the comment form is closed at this time.