Unless you have the numbers in the Senate, an impeachment must have a good reason, because a conviction is NOT going to take place.
Discovery could be a good reason.
Discovery is part of a civil trial. There is no discovery in congressional impeachment. The House votes to impeach on one day and the impeachment trial starts the day after the articles of impeachment are delivered. Other than calling witnesses and cross examining them there isn't much else that is a part of it.