EscaPADE. Escape and Plasma Acceleration and Dynamics Explorers (ESCAPADE) is a planned spacecraft mission to Mars consisting of two spacecraft known as Blue and Gold. The mission, once expected to launch in October 2024, is part of NASA's SIMPLEx program. By May 2024 the spacecraft had reached substantial completion, and in August 2024 the spacecraft arrived at the launch site. However, the launch has been postponed to Spring 2025 due to cost, schedule and technical issues involved with the mission's New Glenn launch vehicle, which was set to debut with the launch of these spacecraft.

Mission 
The mission will demonstrate low-cost planetary space exploration. The twin spacecraft will study Mars' unique magnetosphere and how solar wind contributed to the loss of most of the planet's atmosphere over solar system history.

History 
The Small Innovative Missions for Planetary Exploration ("SIMPLEx") program was intended as a program to select small, low-cost space missions to fly as secondary payloads on other NASA missions. As a ride-along mission on another launch, not a main mission, they were intended to have low cost and tolerate a higher level of risk than other NASA missions.

EscaPADE was originally selected from a competition to be a low-cost ride-along "mission of opportunity" to hitch a ride to Mars with the Psyche spacecraft, and drop off as the spacecraft made a fly-by of Mars. Thus, it had an anticipated launch cost of nearly nothing. However, the launch of the Psyche mission was awarded to Falcon Heavy, meaning that Psyche will make a higher-energy 
flyby of Mars, and EscaPADE mission plans could not be updated in time for the launch. 
Rather than cancel the mission, NASA announced that it would go on a different launch vehicle, and requested bids from industry for the launch.

In February 2023, Blue Origin won the contract to launch the mission on the first flight of the New Glenn launch vehicle in October 2024, at a cost of ~$20 million.

On 6 September 2024, the launch was delayed by NASA to spring 2025 at the earliest.  NASA said, "The agency’s decision to stand down was based on a review of launch preparations and discussions with Blue Origin, the Federal Aviation Administration, and Space Launch Delta 45 Range Safety Organization, as well as NASA’s Launch Services Program and Science Mission Directorate.  The decision was made to avoid significant cost, schedule, and technical challenges associated with potentially removing fuel from the spacecraft in the event of a launch delay, which could be caused by a number of factors."

Spacecraft 

Each identical ESCAPADE spacecraft has a dry mass of ~, with a wet mass of <. The spacecraft bus is originally adapted from the Rocket Lab Photon upper stage and is approximately . The spacecraft is powered by two  solar array wings. Chemical propulsion is provided by thrusters from Arianespace. Reaction wheels, inertial measurement units, and star trackers are used to maintain orientation, with cold gas thrusters to desaturate the wheels. Communications are in X-band via a  diameter dish antenna. A  boom extends above the spacecraft, hosting the EMAG and ELP mNLP sensors.

After launch, ESCAPADE will be directly injected onto an interplanetary trajectory.  It will execute one major and several minor propulsive maneuvers during its 11-month cruise to Mars.  After reaching Mars, the twin probes will enter a highly elliptical orbit. Over the following six months, the orbit will be lowered and circularized until it reaches the nominal science orbit.

Instruments and science goals 

The science goals of ESCAPADE are to:
 understand the processes controlling the structure of Mars' hybrid magnetosphere and how it guides ion flows
 understand how energy and momentum are transported from the solar wind through Mars' magnetosphere
 understand the processes controlling the flow of energy and matter into and out of the collisional atmosphere

There are three science experiments onboard each identical spacecraft: EMAG, EESA, and ELP. EMAG is a magnetometer that will measure DC magnetic fields up to 1000 nT, mounted at the end of the boom to reduce magnetic noise from the spacecraft. EESA is an electrostatic analyzer designed to measure the energies, fluxes, and masses of suprathermal ions from 2 eV to 20 keV and energies and fluxes of suprathermal electrons from 3 eV to 10 keV. It is mounted on the upper deck of the spacecraft bus, with a 240° x 120° field of view for electrons and 247.5° x 90° field of view for ions. ELP is a Langmuir probe consisting of three separate sensors: the multi-needle Langmuir probe (mNLP) consists of 4 thin needles mounted in two pairs ~3/4 way up the boom and measures thermal electron density; the two planar ion probes (PIPs) are mounted on the instrument deck and measure thermal ion density, and the floating potential probe (FPP) is also mounted on the spacecraft deck and measures changes in relative spacecraft electrostatic potential.

Once the nominal science orbit is achieved, approximately six months after arriving at Mars, Science Campaign A involves both spacecraft flying in the same orbit at varying distances from one another, ~ (5.66 hours) with an inclination of 65 degrees. This will last approximately six months, at which time Blue will lower its apoapsis to  and Gold will raise its apoapsis to . With different orbital periods (4.9 and 6.6 hours), the orbits will precess (due to Mars' nonuniform gravity field) at different rates and thus separate, allowing simultaneous measurements of distant parts of the Mars magnetosphere. This campaign will operate for approximately five months until the end of the nominal science mission less than three years after launch.

See also 
List of missions to Mars
Venus Life Finder

References

Further reading 

 ESCAPADE: A TWIN-SPACECRAFT SIMPLEX MISSION TO UNVEIL MARS’ UNIQUE HYBRID MAGNETOSPHERE
 ESCAPADE: A Low-Cost Formation at Mars

NASA space probes
Missions to Mars
2024 in spaceflight