diff --git a/gui/SimOptionsWindow.cpp b/gui/SimOptionsWindow.cpp
index 3342b03..49fa931 100644
--- a/gui/SimOptionsWindow.cpp
+++ b/gui/SimOptionsWindow.cpp
@@ -1,14 +1,65 @@
+
+/// \cond
+// C headers
+// C++ headers
+#include <memory>
+// 3rd party headers
+/// \endcond
+
+// qtrocket headers
+#include "QtRocket.h"
 #include "SimOptionsWindow.h"
 #include "ui_SimOptionsWindow.h"
 
+#include "sim/SimulationOptions.h"
+
 SimOptionsWindow::SimOptionsWindow(QWidget *parent) :
     QMainWindow(parent),
     ui(new Ui::SimOptionsWindow)
 {
     ui->setupUi(this);
+
+    // populate the combo boxes
+    QtRocket* qtrocket = QtRocket::getInstance();
+
+    std::shared_ptr<sim::SimulationOptions> options(new sim::SimulationOptions);
+    std::vector<std::string> atmosphereModels = options->getAvailableAtmosphereModels();
+    std::vector<std::string> gravityModels = options->getAvailableGravityModels();
+
+    for(const auto& i : atmosphereModels)
+    {
+        ui->atmosphereModelCombo->addItem(QString::fromStdString(i));
+    }
+    for(const auto& i : gravityModels)
+    {
+        ui->gravityModelCombo->addItem(QString::fromStdString(i));
+    }
 }
 
 SimOptionsWindow::~SimOptionsWindow()
 {
     delete ui;
 }
+
+void SimOptionsWindow::on_buttonBox_rejected()
+{
+    this->close();
+}
+
+
+void SimOptionsWindow::on_buttonBox_accepted()
+{
+    QtRocket* qtrocket = QtRocket::getInstance();
+
+    std::shared_ptr<sim::SimulationOptions> options(new sim::SimulationOptions);
+
+    options->setTimeStep(ui->timeStep->text().toDouble());
+    options->setGravityModel(ui->gravityModelCombo->currentText().toStdString());
+    options->setAtmosphereModel(ui->atmosphereModelCombo->currentText().toStdString());
+    qtrocket->setSimulationOptions(options);
+
+    this->close();
+
+
+}
+
diff --git a/gui/SimOptionsWindow.h b/gui/SimOptionsWindow.h
index 9d160b1..203b918 100644
--- a/gui/SimOptionsWindow.h
+++ b/gui/SimOptionsWindow.h
@@ -15,6 +15,11 @@ public:
     explicit SimOptionsWindow(QWidget *parent = nullptr);
     ~SimOptionsWindow();
 
+private slots:
+    void on_buttonBox_rejected();
+
+    void on_buttonBox_accepted();
+
 private:
     Ui::SimOptionsWindow *ui;
 };
diff --git a/gui/SimOptionsWindow.ui b/gui/SimOptionsWindow.ui
index 1cbe0ce..eec5505 100644
--- a/gui/SimOptionsWindow.ui
+++ b/gui/SimOptionsWindow.ui
@@ -26,7 +26,7 @@
       <x>60</x>
       <y>20</y>
       <width>261</width>
-      <height>131</height>
+      <height>156</height>
      </rect>
     </property>
     <layout class="QFormLayout" name="formLayout">
diff --git a/sim/SimulationOptions.h b/sim/SimulationOptions.h
index 68cba03..6b3db27 100644
--- a/sim/SimulationOptions.h
+++ b/sim/SimulationOptions.h
@@ -4,6 +4,7 @@
 /// \cond
 // C headers
 // C++ headers
+#include <algorithm>
 #include <map>
 #include <memory>
 #include <string>
@@ -32,9 +33,9 @@ class SimulationOptions
 public:
     SimulationOptions()
     {
-        setTimeStep(0.01);
-        setGravityModel("Constant Gravity");
-        setAtmosphereModel("Constant Atmosphere");
+        //setTimeStep(0.01);
+        //setGravityModel("Constant Gravity");
+        //setAtmosphereModel("Constant Atmosphere");
     }
     ~SimulationOptions() = default;
     SimulationOptions(const SimulationOptions&) = delete;
@@ -42,6 +43,22 @@ public:
     SimulationOptions& operator=(const SimulationOptions&) = delete;
     SimulationOptions& operator=(SimulationOptions&&) = delete;
 
+    std::vector<std::string> getAvailableGravityModels()
+    {
+        std::vector<std::string> retVal(gravityModels.size());
+        std::transform(gravityModels.begin(), gravityModels.end(), std::back_inserter(retVal),
+                  [](auto& i) { return i.first; });
+        return retVal;
+    }
+
+    std::vector<std::string> getAvailableAtmosphereModels()
+    {
+        std::vector<std::string> retVal(atmosphereModels.size());
+        std::transform(atmosphereModels.begin(), atmosphereModels.end(), std::back_inserter(retVal),
+                  [](auto& i) { return i.first; });
+        return retVal;
+    }
+
     void setTimeStep(double t) { timeStep = t; }
     void setGravityModel(const std::string& model)
     {