unexpected symbol 'rigidbody2D'

 using UnityEngine;
 using System.Collections;
 
 public class RocketScript : MonoBehaviour {
     public Vector2 speed = new Vector2(0, 20);
     
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
 
 
 
 
     
     }
     void FixedUpdate () {
         if (Input.GetKeyDown(KeyCode.UpArrow)
 
             rigidbody2D.velocity=speed;
         
         
     }
 }
 
 
 thats my code and it keeps saying that. Whats wrong with it? Any help would be appreciated.