DANDE's Mission

Mission Statement

The DANDE mission will explore the spatial and temporal variability of the neutral thermosphere at altitudes of 325-500 km, and investigate how wind and density variability translate to drag forces on satellites.

Mission Objectives

  1. Establish and understand the relationship between total mass density, composition, and winds as functions of latitude, level of magnetic activity, and horizontal scale.

  2. Establish the relative contributions of density and winds to satellite drag as a function of latitude, level of magnetic activity, and horizontal scale.

  3. Demonstrate key technologies for performing in-situ measurements of the orbital drag environment at low cost.

  4. Improve understanding of the variation in coefficient of drag in the 325-500 km altitude region.

Mission Concept

DANDE's mission concept is illustrated below:

 

 

DANDE will be launching with CSA's Cassiope. We will be in the same orbit as the Canadian satellite which has the following parameters.

Orbit: Elliptical polar orbit, 324 km x 1500 km, inclination =80º, period = 103 minutes (14 orbits/day) (source)

DANDE will launch as a secondary payload attached to the upper stage of SpaceX's Falcon 9. Electrical and mechanical inhibits will ensure that no portion of DANDE becomes active before separation from the launch vehicle.

 

At a predetermined time and location decided by SpaceX, DANDE will separate from the launch vehicle.  Once clear of the launch vehicle, the inhibits will allow DANDE to power up for the first time since leaving Earth, and will not begin to beacon until 30 minutes after being ejected from the launch vehicle.

 

Day 1

When DANDE powers up and begins to beacon, it will automatically enter "Safe Mode."  This mode will allow DANDE to charge its batteries and respond to ground commands.  This mode is "safe" because DANDE can safely stay in this mode indefinitely while tumbling (without attitude control) and charging the batteries.

At this time the DANDE team will begin to track the satellite and listen for beacons.

After hearing beacons and determining that DANDE is OK to contact, the second part of activation will start. The DANDE team will be downloading files to determine the health of the spacecraft.

 

Day 14

At an altitude near perigee (350km), the Lightband Adapter Bracket (LAB) will be released from the spacecraft, leaving DANDE in the spherical configuration required for attitude adjustment and ultimately, science commissioning.

 

 

Days 15 - 25

In order to prepare for science data collection, DANDE will use magnetometers and torque rods to stabilize, align, and spin the spacecraft into the right orientation for nominal operations.

The science instruments will also be tested and undergo a "bakeout" to drive off contaminants that might affect readings.

Science operations: instrument checkouts

 

Days 25 - loss of contact

During science mode, the three science instruments will take data at precise time intervals. This data will be processed and stored for later downlink.  Science mode will periodically pause so that the spacecraft can enter safe mode to recharge its batteries, followed by a brief re-spin operation to prepare for the next science mode period.

Science operations: full instrument operations of the Neutral Mass Spectrometer, Accelerometers, and Attitude Determination and Control.

 

Science instrument characterization

 

Both NMS and ACC need to be characterized and verified to be working before we downlink science data that can be distributed to the public.

 

ACC characterization – has already been tested on the ground. The sensitivity of the subsystem needs to be characterized by seeing at what altitude the instrument no longer takes data.

NMS characterization – because NMS is so complex, on orbit the subsystem needs to have a sequence of component turn on times with data downlink in between each step.

 

The following steps should be taken at perigee in order to receive a strong signal in the data.

1)    Take data before ionizer and filament is burned – data shouldn’t make a lot of sense, but shows that NMS is on and functional.

2)    Turn on ionizer – should return empty data.

3)     Burn the filament – should return data that we are looking for.

 

 Targeted Data Collection: Solar Storms (Solar Mass Ejections)

 

1)    Documenting reported and predicted events

2)    Determining a Storm Event

3)    Notify appropriate personnel to get approval to proceed

4)    Determine data collection and downlink plans

5)     Execute collection and downlink plan

 

Approximately every two weeks, a geomagnetic storm will occur.  DANDE will take data both during storm periods, and during quiet periods before and after each storm to allow comparison of atmospheric variations between the two.

Science operations: full instrument operations.

 

Until end of communication ability,

DANDE will pass over its ground station several times a day.  During these short periods (3 - 11 minutes), the ground station will initiate communications with DANDE, downlink stored science and engineering data, and uplink any commands and information necessary for the next period of operations.

Science operations: briefly paused during communications.

 

Because of DANDE's (and Cassiope's) highly eccentric orbit, the satellite will lose the ability to communicate before it re-enters the atmosphere and burns up. The spacecraft is expected to be operational for about 1.5 years before solar radiation disables DANDE's communication abilities. According to STK analyses, DANDE will be in orbit for about 18 more years before it burns up in the atmosphere as it re-enters. 

 

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